Chapter 66. Core engine API for the process engine

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The process engine executes business processes. To define the processes, you create business assets, including process definitions and custom tasks.

You can use the Core Engine API to load, execute, and manage processes in the process engine.

Several levels of control are available:

At the lowest level, you can directly create a KIE base and a KIE session. A KIE base represents all the assets in a business process. A KIE session is an entity in the process engine that runs instances of a business process. This level provides fine-grained control, but requires explicit declaration and configuration of process instances, task handlers, event handlers, and other process engine entities in your code.
You can use the RuntimeManager class to manage sessions and processes. This class provides sessions for required process instances using a configurable strategy. It automatically configures the interaction between the KIE session and task services. It disposes of process engine entities that are no longer necessary, ensuring optimal use of resources. You can use a fluent API to instantiate RuntimeManager with the necessary business assets and to configure its environment.
You can use the Services API to manage the execution of processes. For example, the deployment service deploys business assets into the engine, forming a deployment unit. The process service runs a process from this deployment unit.
If you want to embed the process engine in your application, the Services API is the most convenient option, because it hides the internal details of configuring and managing the engine.
Finally, you can deploy a KIE Server that loads business assets from KJAR files and runs processes. The KIE Server provides a REST API for loading and managing the processes. You can also use Business Central to manage a KIE Server.
If you use a KIE Server, you do not need to use the Core Engine API. For information about deploying and managing processes on a KIE Server, see Packaging and deploying a Red Hat Process Automation Manager project.

For the full reference information for all public process engine API calls, see the Java documentation. Other API classes also exist in the code, but they are internal APIs that can be changed in later versions. Use public APIs in applications that you develop and maintain.

66.1. KIE base and KIE session

A KIE base contains a reference to all process definitions and other assets relevant for a process. The engine uses this KIE base to look up all information for the process, or for several processes, whenever necessary.

You can load assets into a KIE base from various sources, such as a class path, file system, or process repository. Creating a KIE base is a resource-heavy operation, as it involves loading and parsing assets from various sources. You can dynamically modify the KIE base to add or remove process definitions and other assets at run time.

After you create a KIE base, you can instantiate a KIE session based on this KIE base. Use this KIE session to run processes based on the definitions in the KIE base.

When you use the KIE session to start a process, a new process instance is created. This instance maintains a specific process state. Different instances in the same KIE session can use the same process definition but have different states.

Figure 66.1. KIE base and KIE session in the process engine

For example, if you develop an application to process sales orders, you can create one or more process definitions that determine how an order should be processed. When starting the application, you first need to create a KIE base that contains those process definitions. You can then create a session based on this KIE base. When a new sales order comes in, start a new process instance for the order. This process instance contains the state of the process for the specific sales request.

You can create many KIE sessions for the same KIE base and you can create many instances of the process within the same KIE session. Creating a KIE session, and also creating a process instance within the KIE session, uses far fewer resources than creating a KIE base. If you modify a KIE base, all the KIE sessions that use it can use the modifications automatically.

In most simple use cases, you can use a single KIE session to execute all processes. You can also use several sessions if needed. For example, if you want order processing for different customers to be completely independent, you can create a KIE session for each customer. You can also use multiple sessions for scalability reasons.

In typical applications you do not need to create a KIE base or KIE session directly. However, when you use other levels of the process engine API, you can interact with elements of the API that this level defines.

66.1.1. KIE base

The KIE base includes all process definitions and other assets that your application might need to execute a business process.

To create a KIE base, use a KieHelper instance to load processes from various resources, such as the class path or the file system, and to create a new KIE base.

The following code snippet shows how to create a KIE base consisting of only one process definition, which is loaded from the class path.

Creating a KIE base containing one process definition

  KieHelper kieHelper = new KieHelper();
  KieBase kieBase = kieHelper
    .addResource(ResourceFactory.newClassPathResource("MyProcess.bpmn"))
    .build();

The ResourceFactory class has similar methods to load resources from a file, a URL, an InputStream, a Reader, and other sources.

Note

This "manual" process of creating a KIE base is simpler than other alternatives, but can make an application hard to maintain. Use other methods of creating a KIE base, such as the RuntimeManager class or the Services API, for applications that you expect to develop and maintain over long periods of time.

66.1.2. KIE session

After creating and loading the KIE base, you can create a KIE session to interact with the process engine. You can use this session to start and manage processes and to signal events.

The following code snippet creates a session based on the KIE base that you created previously and then starts a process instance, referencing the ID in the process definition.

Creating a KIE session and starting a process instance

KieSession ksession = kbase.newKieSession();
ProcessInstance processInstance = ksession.startProcess("com.sample.MyProcess");

66.1.3. ProcessRuntime interface

The KieSession class exposes the ProcessRuntime interface, which defines all the session methods for interacting with processes, as the following definition shows.

Definition of the ProcessRuntime interface

  /**
	 * Start a new process instance.  Use the process (definition) that
	 * is referenced by the given process ID.
	 *
	 * @param processId  The ID of the process to start
	 * @return the ProcessInstance that represents the instance of the process that was started
	 */
    ProcessInstance startProcess(String processId);

    /**
	 * Start a new process instance.  Use the process (definition) that
	 * is referenced by the given process ID.  You can pass parameters
	 * to the process instance as name-value pairs, and these parameters set
	 * variables of the process instance.
   *
	 * @param processId  the ID of the process to start
   * @param parameters  the process variables to set when starting the process instance
	 * @return the ProcessInstance that represents the instance of the process that was started
     */
    ProcessInstance startProcess(String processId,
                                 Map<String, Object> parameters);

    /**
     * Signals the process engine that an event has occurred. The type parameter defines
     * the type of event and the event parameter can contain additional information
     * related to the event.  All process instances that are listening to this type
     * of (external) event will be notified.  For performance reasons, use this type of
     * event signaling only if one process instance must be able to notify
     * other process instances. For internal events within one process instance, use the
     * signalEvent method that also include the processInstanceId of the process instance
     * in question.
     *
     * @param type the type of event
     * @param event the data associated with this event
     */
    void signalEvent(String type,
                     Object event);

    /**
     * Signals the process instance that an event has occurred. The type parameter defines
     * the type of event and the event parameter can contain additional information
     * related to the event.  All node instances inside the given process instance that
     * are listening to this type of (internal) event will be notified.  Note that the event
     * will only be processed inside the given process instance.  All other process instances
     * waiting for this type of event will not be notified.
     *
     * @param type the type of event
     * @param event the data associated with this event
     * @param processInstanceId the id of the process instance that should be signaled
     */
    void signalEvent(String type,
                     Object event,
                     long processInstanceId);

    /**
     * Returns a collection of currently active process instances.  Note that only process
     * instances that are currently loaded and active inside the process engine are returned.
     * When using persistence, it is likely not all running process instances are loaded
     * as their state is stored persistently.  It is best practice not to use this
     * method to collect information about the state of your process instances but to use
     * a history log for that purpose.
     *
     * @return a collection of process instances currently active in the session
     */
    Collection<ProcessInstance> getProcessInstances();

    /**
     * Returns the process instance with the given ID.  Note that only active process instances
     * are returned. If a process instance has been completed already, this method returns
     * null.
     *
     * @param id the ID of the process instance
     * @return the process instance with the given ID, or null if it cannot be found
     */
    ProcessInstance getProcessInstance(long processInstanceId);

    /**
     * Aborts the process instance with the given ID. If the process instance has been completed
     * (or aborted), or if the process instance cannot be found, this method will throw an
     * IllegalArgumentException.
     *
     * @param id the ID of the process instance
     */
    void abortProcessInstance(long processInstanceId);

    /**
     * Returns the WorkItemManager related to this session. This object can be used to
     * register new WorkItemHandlers or to complete (or abort) WorkItems.
     *
     * @return the WorkItemManager related to this session
     */
    WorkItemManager getWorkItemManager();

66.1.4. Correlation Keys

When working with processes, you might need to assign a business identifier to a process instance and then use the identifier to reference the instance without storing the generated instance ID.

To provide such capabilities, the process engine uses the CorrelationKey interface, which can define CorrelationProperties. A class that implements CorrelationKey can have either a single property describing it or a multi-property set. The value of the property or a combination of values of several properties refers to a unique instance.

The KieSession class implements the CorrelationAwareProcessRuntime interface to support correlation capabilities. This interface exposes the following methods:

Methods of the CorrelationAwareProcessRuntime interface

      /**
      * Start a new process instance.  Use the process (definition) that
      * is referenced by the given process ID.  You can pass parameters
      * to the process instance (as name-value pairs), and these parameters set
      * variables of the process instance.
      *
      * @param processId  the ID of the process to start
      * @param correlationKey custom correlation key that can be used to identify the process instance
      * @param parameters  the process variables to set when starting the process instance
      * @return the ProcessInstance that represents the instance of the process that was started
      */
      ProcessInstance startProcess(String processId, CorrelationKey correlationKey, Map<String, Object> parameters);

      /**
      * Create a new process instance (but do not yet start it).  Use the process
      * (definition) that is referenced by the given process ID.
      * You can pass to the process instance (as name-value pairs),
      * and these parameters set variables of the process instance.
      * Use this method if you need a reference to the process instance before actually
      * starting it.  Otherwise, use startProcess.
      *
      * @param processId  the ID of the process to start
      * @param correlationKey custom correlation key that can be used to identify the process instance
      * @param parameters  the process variables to set when creating the process instance
      * @return the ProcessInstance that represents the instance of the process that was created (but not yet started)
      */
      ProcessInstance createProcessInstance(String processId, CorrelationKey correlationKey, Map<String, Object> parameters);

      /**
      * Returns the process instance with the given correlationKey.  Note that only active process instances
      * are returned.  If a process instance has been completed already, this method will return
      * null.
      *
      * @param correlationKey the custom correlation key assigned when the process instance was created
      * @return the process instance identified by the key or null if it cannot be found
      */
      ProcessInstance getProcessInstance(CorrelationKey correlationKey);

Correlation is usually used with long-running processes. You must enable persistence if you want to store correlation information permanently.

66.2. Runtime manager

The RuntimeManager class provides a layer in the process engine API that simplifies and empowers its usage. This class encapsulates and manages the KIE base and KIE session, as well as the task service that provides handlers for all tasks in the process. The KIE session and the task service within the runtime manager are already configured to work with each other and you do not need to provide such configuration. For example, you do not need to register a human task handler and to ensure that it is connected to the required service.

The runtime manager manages the KIE session according to a predefined strategy. The following strategies are available:

Singleton: The runtime manager maintains a single KieSession and uses it for all the requested processes.
Per Request: The runtime manager creates a new KieSession for every request.
Per Process Instance: The runtime manager maintains mapping between process instance and KieSession and always provides the same KieSession whenever working with a given process instance.

Regardless of the strategy, the RuntimeManager class ensures the same capabilities in initialization and configuration of the process engine components:

KieSession instances are loaded with the same factories (either in memory or JPA based).
Work item handlers are registered on every KieSession instance (either loaded from the database or newly created).
Event listeners (Process, Agenda, WorkingMemory) are registered on every KIE session, whether the session is loaded from the database or newly created.
The task service is configured with the following required components:
- The JTA transaction manager
- The same entity manager factory as the one used for KieSession instances
- The UserGroupCallback instance that can be configured in the environment

The runtime manager also enables disposing the process engine cleanly. It provides dedicated methods to dispose a RuntimeEngine instance when it is no longer needed, releasing any resources it might have acquired.

The following code shows the definition of the RuntimeManager interface:

Definition of the RuntimeManager interface

public interface RuntimeManager {

	/**
	 * Returns a <code>RuntimeEngine</code> instance that is fully initialized:
	 * <ul>
	 * 	<li>KieSession is created or loaded depending on the strategy</li>
	 * 	<li>TaskService is initialized and attached to the KIE session (through a listener)</li>
	 * 	<li>WorkItemHandlers are initialized and registered on the KIE session</li>
	 * 	<li>EventListeners (process, agenda, working memory) are initialized and added to the KIE session</li>
	 * </ul>
	 * @param context the concrete implementation of the context that is supported by given <code>RuntimeManager</code>
	 * @return instance of the <code>RuntimeEngine</code>
	 */
    RuntimeEngine getRuntimeEngine(Context<?> context);

    /**
     * Unique identifier of the <code>RuntimeManager</code>
     * @return
     */
    String getIdentifier();

    /**
     * Disposes <code>RuntimeEngine</code> and notifies all listeners about that fact.
     * This method should always be used to dispose <code>RuntimeEngine</code> that is not needed
     * anymore. <br/>
     * Do not use KieSession.dispose() used with RuntimeManager as it will break the internal
     * mechanisms of the manager responsible for clear and efficient disposal.<br/>
     * Disposing is not needed if <code>RuntimeEngine</code> was obtained within an active JTA transaction,
     * if the getRuntimeEngine method was invoked during active JTA transaction, then disposing of
     * the runtime engine will happen automatically on transaction completion.
     * @param runtime
     */
    void disposeRuntimeEngine(RuntimeEngine runtime);

    /**
     * Closes <code>RuntimeManager</code> and releases its resources. Call this method when
     * a runtime manager is not needed anymore. Otherwise it will still be active and operational.
     */
    void close();

}

The RuntimeManager class also provides the RuntimeEngine class, which includes methods to get access to underlying process engine components:

Definition of the RuntimeEngine interface

public interface RuntimeEngine {

	/**
	 * Returns the <code>KieSession</code> configured for this <code>RuntimeEngine</code>
	 * @return
	 */
    KieSession getKieSession();

    /**
	 * Returns the <code>TaskService</code> configured for this <code>RuntimeEngine</code>
	 * @return
	 */
    TaskService getTaskService();
}

Note

An identifier of the RuntimeManager class is used as deploymentId during runtime execution. For example, the identifier is persisted as deploymentId of a Task when the Task is persisted. The deploymentID of a Task associates it with the RuntimeManager when the Task is completed and the process instance is resumed.

The same deploymentId is also persisted as externalId in history log tables.

If you don’t specify an identifier when creating a RuntimeManager instance, a default value is applied, depending on the strategy (for example, default-per-pinstance for PerProcessInstanceRuntimeManager). That means your application uses the same deployment of the RuntimeManager class in its entire lifecycle.

If you maintain multiple runtime managers in your application, you must specify a unique identifier for every RuntimeManager instance.

For example, the deployment service maintains multiple runtime managers and uses the GAV value of the KJAR file as an identifier. The same logic is used in Business Central and in KIE Server, because they depend on the deployment service.

Note

When you need to interact with the process engine or task service from within a handler or a listener, you can use the RuntimeManager interface to retrieve the RuntimeEngine instance for the given process instance, and then use the RuntimeEngine instance to retrieve the KieSession or TaskService instance. This approach ensures that the proper state of the engine, managed according to the selected strategy, is preserved.

66.2.1. Runtime manager strategies

The RuntimeManager class supports the following strategies for managing KIE sessions.

Singleton strategy

This strategy instructs the runtime manager to maintain a single RuntimeEngine instance (and in turn single KieSession and TaskService instances). Access to the runtime engine is synchronized and, therefore, thread safe, although it comes with a performance penalty due to synchronization.

Use this strategy for simple use cases.

This strategy has the following characteristics:

It has a small memory footprint, with single instances of the runtime engine and the task service.
It is simple and compact in design and usage.
It is a good fit for low-to-medium load on the process engine because of synchronized access.
In this strategy, because of the single KieSession instance, all state objects (such as facts) are directly visible to all process instances and vice versa.
The strategy is not contextual. When you retrieve instances of RuntimeEngine from a singleton RuntimeManager, you do not need to take the Context instance into account. Usually, you can use EmptyContext.get() as the context, although a null argument is acceptable as well.
In this strategy, the runtime manager keeps track of the ID of the KieSession, so that the same session remains in use after a RuntimeManager restart. The ID is stored as a serialized file in a temporary location in the file system that, depending on the environment, can be one of the following directories:
- The value of the jbpm.data.dir system property
- The value of the jboss.server.data.dir system property
- The value of the java.io.tmpdir system property

Warning

A combination of the Singleton strategy and the EJB Timer Scheduler might raise Hibernate issues under load. Do not use this combination in production applications. The EJB Timer Scheduler is the default scheduler in the KIE Server.

Per request strategy

This strategy instructs the runtime manager to provide a new instance of RuntimeEngine for every request. One or more invocations of the process engine within a single transaction are considered a single request.

The same instance of RuntimeEngine must be used within a single transaction to ensure correctness of state. Otherwise, an operation completed in one call would not be visible in the next call.

This strategy is stateless, as process state is preserved only within the request. When a request is completed, the RuntimeEngine instance is permanently destroyed. If persistence is used, information related to the KIE session is removed from the persistence database as well.

This strategy has the following characteristics:

It provides completely isolated process engine and task service operations for every request.
It is completely stateless, because facts are stored only for the duration of the request.
It is a good fit for high-load, stateless processes, where no facts or timers must be preserved between requests.
In this strategy, the KIE session is only available during the life of a request and is destroyed at the end of the request.
The strategy is not contextual. When you retrieve instances of RuntimeEngine from a per-request RuntimeManager, you do not need to take the Context instance into account. Usually, you can use EmptyContext.get() as the context, although a null argument is acceptable as well.

Per process instance strategy

This strategy instructs RuntimeManager to maintain a strict relationship between a KIE session and a process instance. Each KieSession is available as long as the ProcessInstance to which it belongs is active.

This strategy provides the most flexible approach for using advanced capabilities of the process engine, such as rule evaluation and isolation between process instances. It maximizes performance and reduces potential bottlenecks introduced by synchronization. At the same time, unlike the request strategy, it reduces the number of KIE sessions to the actual number of process instances, rather than the total number of requests.

This strategy has the following characteristics:

It provides isolation for every process instance.
It maintains a strict relationship between KieSession and ProcessInstance to ensure that it always delivers the same KieSession for a given ProcessInstance.
It merges the lifecycle of KieSession with ProcessInstance, and both are disposed when the process instance completes or aborts.
It enables maintenance of data, such as facts and timers, in the scope of the process instance. Only the process instance has access to the data.
It introduces some overhead because of the need to look up and load the KieSession for the process instance.
It validates every usage of a KieSession so it cannot be used for other process instances. An exception is thrown if another process instance uses the same KieSession.
The strategy is contextual and accepts the following context instances:
- EmptyContext or null: Used when starting a process instance because no process instance ID is available yet
- ProcessInstanceIdContext: Used after the process instance is created
- CorrelationKeyContext: Used as an alternative to ProcessInstanceIdContext to use a custom (business) key instead of the process instance ID

66.2.2. Typical usage scenario for the runtime manager

The typical usage scenario for the runtime manager consists of the following stages:

At application startup time, complete the following stage:
- Build a RuntimeManager instance and keep it for the entire lifetime of the application, as it is thread-safe and can be accessed concurrently.
At request time, complete the following stages:
- Get RuntimeEngine from the RuntimeManager, using the proper context instance as determined by the strategy that you configured for the RuntimeManager class.
- Get the KieSession and TaskService objects from the RuntimeEngine.
- Use the KieSession and TaskService objects for operations such as startProcess or completeTask.
- After completing processing, dispose RuntimeEngine using the RuntimeManager.disposeRuntimeEngine method.
At application shutdown time, complete the following stage:
- Close the RuntimeManager instance.

Note

When RuntimeEngine is obtained from RuntimeManager within an active JTA transaction, you do not need to dispose RuntimeEngine at the end, as RuntimeManager automatically disposes the RuntimeEngine on transaction completion (regardless of the completion status: commit or rollback).

The following example shows how you can build a RuntimeManager instance and get a RuntimeEngine instance (that encapsulates KieSession and TaskService classes) from it:

Building a RuntimeManager instance and then getting RuntimeEngine and KieSession

    // First, configure the environment to be used by RuntimeManager
    RuntimeEnvironment environment = RuntimeEnvironmentBuilder.Factory.get()
    .newDefaultInMemoryBuilder()
    .addAsset(ResourceFactory.newClassPathResource("BPMN2-ScriptTask.bpmn2"), ResourceType.BPMN2)
    .get();

    // Next, create the RuntimeManager - in this case the singleton strategy is chosen
    RuntimeManager manager = RuntimeManagerFactory.Factory.get().newSingletonRuntimeManager(environment);

    // Then get RuntimeEngine from the runtime manager, using an empty context because singleton does not keep track
    // of runtime engine as there is only one
    RuntimeEngine runtime = manager.getRuntimeEngine(EmptyContext.get());

    // Get the KieSession from the RuntimeEngine - already initialized with all handlers, listeners, and other requirements
    // configured on the environment
    KieSession ksession = runtimeEngine.getKieSession();

    // Add invocations of the process engine here,
    // for example, ksession.startProcess(processId);

    // Finally, dispose the runtime engine
    manager.disposeRuntimeEngine(runtimeEngine);

This example provides the simplest, or minimal, way of using RuntimeManager and RuntimeEngine classes. It has the following characteristics:

The KieSession instance is created in memory, using the newDefaultInMemoryBuilder builder.
A single process, which is added as an asset, is available for execution.
The TaskService class is configured and attached to the KieSession instance through the LocalHTWorkItemHandler interface to support user task capabilities within processes.

66.2.3. Runtime environment configuration object

The RuntimeManager class encapsulates internal process engine complexity, such as creating, disposing, and registering handlers.

It also provides fine-grained control over process engine configuration. To set this configuration, you must create a RuntimeEnvironment object and then use it to create the RuntimeManager object.

The following definition shows the methods available in the RuntimeEnvironment interface:

Methods in the RuntimeEnvironment interface

  public interface RuntimeEnvironment {

	/**
	 * Returns <code>KieBase</code> that is to be used by the manager
	 * @return
	 */
    KieBase getKieBase();

    /**
     * KieSession environment that is to be used to create instances of <code>KieSession</code>
     * @return
     */
    Environment getEnvironment();

    /**
     * KieSession configuration that is to be used to create instances of <code>KieSession</code>
     * @return
     */
    KieSessionConfiguration getConfiguration();

    /**
     * Indicates if persistence is to be used for the KieSession instances
     * @return
     */
    boolean usePersistence();

    /**
     * Delivers a concrete implementation of <code>RegisterableItemsFactory</code> to obtain handlers and listeners
     * that is to be registered on instances of <code>KieSession</code>
     * @return
     */
    RegisterableItemsFactory getRegisterableItemsFactory();

    /**
     * Delivers a concrete implementation of <code>UserGroupCallback</code> that is to be registered on instances
     * of <code>TaskService</code> for managing users and groups.
     * @return
     */
    UserGroupCallback getUserGroupCallback();

    /**
     * Delivers a custom class loader that is to be used by the process engine and task service instances
     * @return
     */
    ClassLoader getClassLoader();

    /**
     * Closes the environment, permitting closing of all dependent components such as ksession factories
     */
    void close();

66.2.4. Runtime environment builder

To create an instance of RuntimeEnvironment that contains the required data, use the RuntimeEnvironmentBuilder class. This class provides a fluent API to configure a RuntimeEnvironment instance with predefined settings.

The following definition shows the methods in the RuntimeEnvironmentBuilder interface:

Methods in the RuntimeEnvironmentBuilder interface

public interface RuntimeEnvironmentBuilder {

	public RuntimeEnvironmentBuilder persistence(boolean persistenceEnabled);

	public RuntimeEnvironmentBuilder entityManagerFactory(Object emf);

	public RuntimeEnvironmentBuilder addAsset(Resource asset, ResourceType type);

	public RuntimeEnvironmentBuilder addEnvironmentEntry(String name, Object value);

	public RuntimeEnvironmentBuilder addConfiguration(String name, String value);

	public RuntimeEnvironmentBuilder knowledgeBase(KieBase kbase);

	public RuntimeEnvironmentBuilder userGroupCallback(UserGroupCallback callback);

	public RuntimeEnvironmentBuilder registerableItemsFactory(RegisterableItemsFactory factory);

	public RuntimeEnvironment get();

	public RuntimeEnvironmentBuilder classLoader(ClassLoader cl);

	public RuntimeEnvironmentBuilder schedulerService(Object globalScheduler);

Use the RuntimeEnvironmentBuilderFactory class to obtain instances of RuntimeEnvironmentBuilder. Along with empty instances with no settings, you can get builders with several preconfigured sets of configuration options for the runtime manager.

The following definition shows the methods in the RuntimeEnvironmentBuilderFactory interface:

Methods in the RuntimeEnvironmentBuilderFactory interface

public interface RuntimeEnvironmentBuilderFactory {

	/**
     * Provides a completely empty <code>RuntimeEnvironmentBuilder</code> instance to manually
     * set all required components instead of relying on any defaults.
     * @return new instance of <code>RuntimeEnvironmentBuilder</code>
     */
    public RuntimeEnvironmentBuilder newEmptyBuilder();

    /**
     * Provides default configuration of <code>RuntimeEnvironmentBuilder</code> that is based on:
     * <ul>
     * 	<li>DefaultRuntimeEnvironment</li>
     * </ul>
     * @return new instance of <code>RuntimeEnvironmentBuilder</code> that is already preconfigured with defaults
     *
     * @see DefaultRuntimeEnvironment
     */
    public RuntimeEnvironmentBuilder newDefaultBuilder();

    /**
     * Provides default configuration of <code>RuntimeEnvironmentBuilder</code> that is based on:
     * <ul>
     * 	<li>DefaultRuntimeEnvironment</li>
     * </ul>
     * but does not have persistence for the process engine configured so it will only store process instances in memory
     * @return new instance of <code>RuntimeEnvironmentBuilder</code> that is already preconfigured with defaults
     *
     * @see DefaultRuntimeEnvironment
     */
    public RuntimeEnvironmentBuilder newDefaultInMemoryBuilder();

    /**
     * Provides default configuration of <code>RuntimeEnvironmentBuilder</code> that is based on:
     * <ul>
     * 	<li>DefaultRuntimeEnvironment</li>
     * </ul>
     * This method is tailored to work smoothly with KJAR files
     * @param groupId group id of kjar
     * @param artifactId artifact id of kjar
     * @param version version number of kjar
     * @return new instance of <code>RuntimeEnvironmentBuilder</code> that is already preconfigured with defaults
     *
     * @see DefaultRuntimeEnvironment
     */
    public RuntimeEnvironmentBuilder newDefaultBuilder(String groupId, String artifactId, String version);

    /**
     * Provides default configuration of <code>RuntimeEnvironmentBuilder</code> that is based on:
     * <ul>
     * 	<li>DefaultRuntimeEnvironment</li>
     * </ul>
     * This method is tailored to work smoothly with KJAR files and use the kbase and ksession settings in the KJAR
     * @param groupId group id of kjar
     * @param artifactId artifact id of kjar
     * @param version version number of kjar
     * @param kbaseName name of the kbase defined in kmodule.xml stored in kjar
     * @param ksessionName name of the ksession define in kmodule.xml stored in kjar
     * @return new instance of <code>RuntimeEnvironmentBuilder</code> that is already preconfigured with defaults
     *
     * @see DefaultRuntimeEnvironment
     */
    public RuntimeEnvironmentBuilder newDefaultBuilder(String groupId, String artifactId, String version, String kbaseName, String ksessionName);

    /**
     * Provides default configuration of <code>RuntimeEnvironmentBuilder</code> that is based on:
     * <ul>
     * 	<li>DefaultRuntimeEnvironment</li>
     * </ul>
     * This method is tailored to work smoothly with KJAR files and use the release ID defined in the KJAR
     * @param releaseId <code>ReleaseId</code> that described the kjar
     * @return new instance of <code>RuntimeEnvironmentBuilder</code> that is already preconfigured with defaults
     *
     * @see DefaultRuntimeEnvironment
     */
    public RuntimeEnvironmentBuilder newDefaultBuilder(ReleaseId releaseId);

    /**
     * Provides default configuration of <code>RuntimeEnvironmentBuilder</code> that is based on:
     * <ul>
     * 	<li>DefaultRuntimeEnvironment</li>
     * </ul>
		 * This method is tailored to work smoothly with KJAR files and use the kbase, ksession, and release ID settings in the KJAR
     * @param releaseId <code>ReleaseId</code> that described the kjar
     * @param kbaseName name of the kbase defined in kmodule.xml stored in kjar
     * @param ksessionName name of the ksession define in kmodule.xml stored in kjar
     * @return new instance of <code>RuntimeEnvironmentBuilder</code> that is already preconfigured with defaults
     *
     * @see DefaultRuntimeEnvironment
     */
    public RuntimeEnvironmentBuilder newDefaultBuilder(ReleaseId releaseId, String kbaseName, String ksessionName);

    /**
     * Provides default configuration of <code>RuntimeEnvironmentBuilder</code> that is based on:
     * <ul>
     * 	<li>DefaultRuntimeEnvironment</li>
     * </ul>
     * It relies on KieClasspathContainer that requires the presence of kmodule.xml in the META-INF folder which
     * defines the kjar itself.
     * Expects to use default kbase and ksession from kmodule.
     * @return new instance of <code>RuntimeEnvironmentBuilder</code> that is already preconfigured with defaults
     *
     * @see DefaultRuntimeEnvironment
     */
    public RuntimeEnvironmentBuilder newClasspathKmoduleDefaultBuilder();

    /**
     * Provides default configuration of <code>RuntimeEnvironmentBuilder</code> that is based on:
     * <ul>
     * 	<li>DefaultRuntimeEnvironment</li>
     * </ul>
		 * It relies on KieClasspathContainer that requires the presence of kmodule.xml in the META-INF folder which
     * defines the kjar itself.
     * @param kbaseName name of the kbase defined in kmodule.xml
     * @param ksessionName name of the ksession define in kmodule.xml
     * @return new instance of <code>RuntimeEnvironmentBuilder</code> that is already preconfigured with defaults
     *
     * @see DefaultRuntimeEnvironment
     */
    public RuntimeEnvironmentBuilder newClasspathKmoduleDefaultBuilder(String kbaseName, String ksessionName);

The runtime manager also provides access to a TaskService object as an integrated component of a RuntimeEngine object, configured to communicate with the KIE session. If you use one of the default builders, the following configuration settings for the task service are present:

The persistence unit name is set to org.jbpm.persistence.jpa (for both process engine and task service).
The human task handler is registered on the KIE session.
The JPA-based history log event listener is registered on the KIE session.
An event listener to trigger rule task evaluation (fireAllRules) is registered on the KIE session.

66.2.5. Registration of handlers and listeners for runtime engines

If you use the runtime manager API, the runtime engine object represents the process engine.

To extend runtime engines with your own handlers or listeners, you can implement the RegisterableItemsFactory interface and then include it in the runtime environment using the RuntimeEnvironmentBuilder.registerableItemsFactory() method. Then the runtime manager automatically adds the handlers or listeners to every runtime engine it creates.

The following definition shows the methods in the RegisterableItemsFactory interface:

Methods in the RegisterableItemsFactory interface

	/**
	 * Returns new instances of <code>WorkItemHandler</code> that will be registered on <code>RuntimeEngine</code>
	 * @param runtime provides <code>RuntimeEngine</code> in case handler need to make use of it internally
	 * @return map of handlers to be registered - in case of no handlers empty map shall be returned.
	 */
    Map<String, WorkItemHandler> getWorkItemHandlers(RuntimeEngine runtime);

    /**
	 * Returns new instances of <code>ProcessEventListener</code> that will be registered on <code>RuntimeEngine</code>
	 * @param runtime provides <code>RuntimeEngine</code> in case listeners need to make use of it internally
	 * @return list of listeners to be registered - in case of no listeners empty list shall be returned.
	 */
    List<ProcessEventListener> getProcessEventListeners(RuntimeEngine runtime);

    /**
	 * Returns new instances of <code>AgendaEventListener</code> that will be registered on <code>RuntimeEngine</code>
	 * @param runtime provides <code>RuntimeEngine</code> in case listeners need to make use of it internally
	 * @return list of listeners to be registered - in case of no listeners empty list shall be returned.
	 */
    List<AgendaEventListener> getAgendaEventListeners(RuntimeEngine runtime);

    /**
	 * Returns new instances of <code>WorkingMemoryEventListener</code> that will be registered on <code>RuntimeEngine</code>
	 * @param runtime provides <code>RuntimeEngine</code> in case listeners need to make use of it internally
	 * @return list of listeners to be registered - in case of no listeners empty list shall be returned.
	 */
    List<WorkingMemoryEventListener> getWorkingMemoryEventListeners(RuntimeEngine runtime);

The process engine provides default implementations of RegisterableItemsFactory. You can extend these implementations to define custom handlers and listeners.

The following available implementations might be useful:

org.jbpm.runtime.manager.impl.SimpleRegisterableItemsFactory: The simplest possible implementation. It does not have any predefined content and uses reflection to produce instances of handlers and listeners based on given class names.
org.jbpm.runtime.manager.impl.DefaultRegisterableItemsFactory: An extension of the Simple implementation that introduces the same defaults as the default runtime environment builder and still provides the same capabilities as the Simple implementation.
org.jbpm.runtime.manager.impl.cdi.InjectableRegisterableItemsFactory: An extension of the Default implementation that is tailored for CDI environments and provides a CDI style approach to finding handlers and listeners using producers.

66.2.5.1. Registering work item handlers using a file

You can register simple work item handlers, which are stateless or rely on the KieSession state, by defining them in the CustomWorkItem.conf file and placing the file on the class path.

Procedure

Create a file named drools.session.conf in the META-INF subdirectory of the root of the class path. For web applications the directory is WEB-INF/classes/META-INF.

Add the following line to the drools.session.conf file:

drools.workItemHandlers = CustomWorkItemHandlers.conf

Create a file named CustomWorkItemHandlers.conf in the same directory.

In the CustomWorkItemHandlers.conf file, define custom work item handlers using the MVEL style, similar to the following example:

[
  "Log": new org.jbpm.process.instance.impl.demo.SystemOutWorkItemHandler(),
  "WebService": new org.jbpm.process.workitem.webservice.WebServiceWorkItemHandler(ksession),
  "Rest": new org.jbpm.process.workitem.rest.RESTWorkItemHandler(),
  "Service Task" : new org.jbpm.process.workitem.bpmn2.ServiceTaskHandler(ksession)
]

Result

The work item handlers that you listed are registered for any KIE session created by the application, regardless of whether the application uses the runtime manager API.

66.2.5.2. Registration of handlers and listeners in a CDI environment

If your application uses the runtime manager API and runs in a CDI environment, your classes can implement the dedicated producer interfaces to provide custom work item handlers and event listeners to all runtime engines.

To create a work item handler, you must implement the WorkItemHandlerProducer interface.

Definition of the WorkItemHandlerProducer interface

public interface WorkItemHandlerProducer {

    /**
     * Returns a map of work items (key = work item name, value=  work item handler instance)
     * to be registered on the KieSession
     * <br/>
     * The following parameters are accepted:
     * <ul>
     *  <li>ksession</li>
     *  <li>taskService</li>
     *  <li>runtimeManager</li>
     * </ul>
     *
     * @param identifier - identifier of the owner - usually RuntimeManager that allows the producer to filter out
     * and provide valid instances for given owner
     * @param params - the owner might provide some parameters, usually KieSession, TaskService, RuntimeManager instances
     * @return map of work item handler instances (recommendation is to always return new instances when this method is invoked)
     */
    Map<String, WorkItemHandler> getWorkItemHandlers(String identifier, Map<String, Object> params);
}

To create an event listener, you must implement the EventListenerProducer interface. Annotate the event listener producer with the proper qualifier to indicate the type of listeners that it provides. Use one of the following annotations:

@Process for ProcessEventListener
@Agenda for AgendaEventListener
@WorkingMemory for WorkingMemoryEventListener

Definition of the EventListenerProducer interface

public interface EventListenerProducer<T> {

    /**
     * Returns a list of instances for given (T) type of listeners
     * <br/>
     * The following parameters are accepted:
     * <ul>
     *  <li>ksession</li>
     *  <li>taskService</li>
     *  <li>runtimeManager</li>
     * </ul>
     * @param identifier - identifier of the owner - usually RuntimeManager that allows the producer to filter out
     * and provide valid instances for given owner
     * @param params - the owner might provide some parameters, usually KieSession, TaskService, RuntimeManager instances
     * @return list of listener instances (recommendation is to always return new instances when this method is invoked)
     */
    List<T> getEventListeners(String identifier, Map<String, Object>  params);
}

Package your implementations of these interfaces as a bean archive by including beans.xml in the META-INF subdirectory. Place the bean archive on the application class path, for example, in WEB-INF/lib for a web application. The CDI-based runtime manager discovers the packages and registers the work item handlers and event listeners in every KieSession that it creates or loads from the data store.

The process engine provides certain parameters to the producers to enable stateful and advanced operation. For example, the handlers or listeners can use the parameters to signal the process engine or the process instance in case of an error. The process engine provides the following components as parameters:

KieSession
TaskService
RuntimeManager

In addition, the identifier of the RuntimeManager class instance is provided as a parameter. You can apply filtering to the identifier to decide whether this RuntimeManager instance receives the handlers and listeners.

66.3. Services in the process engine

The process engine provides a set of high-level services, running on top of the runtime manager API.

The services provide the most convenient way to embed the process engine in your application. The KIE Server also uses these services internally.

When you use services, you do not need to implement your own handling of the runtime manager, runtime engines, sessions, and other process engine entities. However, you can access the underlying RuntimeManager objects through the services when necessary.

Note

If you use the EJB remote client for the services API, the RuntimeManager objects are not available, because they would not operate correctly on the client side after serialization.

66.3.1. Modules for process engine services

The process engine services are provided as a set of modules. These modules are grouped by their framework dependencies. You can choose the suitable modules and use only these modules, without making your application dependent on the frameworks that other modules use.

The following modules are available:

jbpm-services-api: Only API classes and interfaces
jbpm-kie-services: A code implementation of the services API in pure Java without any framework dependencies
jbpm-services-cdi: A CDI wrapper on top of the core services implementation
jbpm-services-ejb-api: An extension of the services API to support EJB requirements
jbpm-services-ejb-impl: EJB wrappers on top of the core services implementation
jbpm-services-ejb-timer: A scheduler service based on the EJB timer service to support time-based operations, such as timer events and deadlines
jbpm-services-ejb-client: An EJB remote client implementation, currently supporting only Red Hat JBoss EAP

66.3.2. Deployment service

The deployment service deploys and undeploys units in the process engine.

A deployment unit represents the contents of a KJAR file. A deployment unit includes business assets, such as process definitions, rules, forms, and data models. After deploying the unit you can execute the processes it defines. You can also query the available deployment units.

Every deployment unit has a unique identifier string, deploymentId, also known as deploymentUnitId. You can use this identifier to apply any service actions to the deployment unit.

In a typical use case for this service, you can load and unload multiple KJARs at the same time and, when necessary, execute processes simultaneously.

The following code sample shows simple use of the deployment service.

Using the deployment service

// Create deployment unit by providing the GAV of the KJAR
DeploymentUnit deploymentUnit = new KModuleDeploymentUnit(GROUP_ID, ARTIFACT_ID, VERSION);
// Get the deploymentId for the deployed unit
String deploymentId = deploymentUnit.getIdentifier();
// Deploy the unit
deploymentService.deploy(deploymentUnit);
// Retrieve the deployed unit
DeployedUnit deployed = deploymentService.getDeployedUnit(deploymentId);
// Get the runtime manager
RuntimeManager manager = deployed.getRuntimeManager();

The following definition shows the complete DeploymentService interface:

Definition of the DeploymentService interface

public interface DeploymentService {

    void deploy(DeploymentUnit unit);

    void undeploy(DeploymentUnit unit);

    RuntimeManager getRuntimeManager(String deploymentUnitId);

    DeployedUnit getDeployedUnit(String deploymentUnitId);

    Collection<DeployedUnit> getDeployedUnits();

    void activate(String deploymentId);

    void deactivate(String deploymentId);

    boolean isDeployed(String deploymentUnitId);
}

66.3.3. Definition service

When you deploy a process definition using the deployment service, the definition service automatically scans the definition, parses the process, and extracts the information that the process engine requires.

You can use the definition service API to retrieve information about the process definition. The service extracts this information directly from the BPMN2 process definition. The following information is available:

Process definition such as ID, name, and description
Process variables including the name and type of every variable
Reusable sub-processes used in the process (if any)
Service tasks that represent domain-specific activities
User tasks including assignment information
Task data with input and output information

The following code sample shows simple use of the definition service. The processID must correspond to the ID of a process definition in a KJAR file that you already deployed using the deployment service.

Using the definition service

String processId = "org.jbpm.writedocument";

Collection<UserTaskDefinition> processTasks =
bpmn2Service.getTasksDefinitions(deploymentUnit.getIdentifier(), processId);

Map<String, String> processData =
bpmn2Service.getProcessVariables(deploymentUnit.getIdentifier(), processId);

Map<String, String> taskInputMappings =
bpmn2Service.getTaskInputMappings(deploymentUnit.getIdentifier(), processId, "Write a Document" );

You can also use the definition service to scan a definition that you provide as BPMN2-compliant XML content, without the use of a KJAR file. The buildProcessDefinition method provides this capability.

The following definition shows the complete DefinitionService interface:

Definition of the DefinitionService interface

public interface DefinitionService {

    ProcessDefinition buildProcessDefinition(String deploymentId, String bpmn2Content, ClassLoader classLoader, boolean cache) throws IllegalArgumentException;

    ProcessDefinition getProcessDefinition(String deploymentId, String processId);

    Collection<String> getReusableSubProcesses(String deploymentId, String processId);

    Map<String, String> getProcessVariables(String deploymentId, String processId);

    Map<String, String> getServiceTasks(String deploymentId, String processId);

    Map<String, Collection<String>> getAssociatedEntities(String deploymentId, String processId);

    Collection<UserTaskDefinition> getTasksDefinitions(String deploymentId, String processId);

    Map<String, String> getTaskInputMappings(String deploymentId, String processId, String taskName);

    Map<String, String> getTaskOutputMappings(String deploymentId, String processId, String taskName);

}

66.3.4. Process service

The deployment and definition services prepare process data in the process engine. To execute processes based on this data, use the process service. The process service supports interaction with the process engine execution environment, including the following actions:

Starting a new process instance
Running a process as a single transaction
Working with an existing process instance, for example, signalling events, getting information details, and setting values of variables
Working with work items

The process service is also a command executor. You can use it to execute commands on the KIE session to extend its capabilities.

Important

The process service is optimized for runtime operations. Use it when you need to run a process or to alter a process instance, for example, signal events or change variables. For read operations, for example, showing available process instances, use the runtime data service.

The following code sample shows deploying and running a process:

Deploying and runing a process using the deployment and process services

KModuleDeploymentUnit deploymentUnit = new KModuleDeploymentUnit(GROUP_ID, ARTIFACT_ID, VERSION);

deploymentService.deploy(deploymentUnit);

long processInstanceId = processService.startProcess(deploymentUnit.getIdentifier(), "customtask");

ProcessInstance pi = processService.getProcessInstance(processInstanceId);

The startProcess method expects deploymentId as the first argument. Using this argument, you can start processes in a certain deployment when your application might have multiple deployments.

For example, you might deploy different versions of the same process from different KJAR files. You can then start the required version using the correct deploymentId.

The following definition shows the complete ProcessService interface:

Definition of the ProcessService interface

public interface ProcessService {

	/**
	 * Starts a process with no variables
	 *
	 * @param deploymentId deployment identifier
	 * @param processId process identifier
	 * @return process instance IDentifier
	 * @throws RuntimeException in case of encountered errors
	 * @throws DeploymentNotFoundException in case a deployment with the given deployment identifier does not exist
	 * @throws DeploymentNotActiveException in case the deployment with the given deployment identifier is not active
	 */
	Long startProcess(String deploymentId, String processId);

	/**
	 * Starts a process and sets variables
	 *
	 * @param deploymentId deployment identifier
	 * @param processId process identifier
	 * @param params process variables
	 * @return process instance IDentifier
	 * @throws RuntimeException in case of encountered errors
	 * @throws DeploymentNotFoundException in case a deployment with the given deployment identifier does not exist
	 * @throws DeploymentNotActiveException in case the deployment with the given deployment identifier is not active
	 */
    Long startProcess(String deploymentId, String processId, Map<String, Object> params);

	/**
	 * Starts a process with no variables and assigns a correlation key
	 *
	 * @param deploymentId deployment identifier
	 * @param processId process identifier
	 * @param correlationKey correlation key to be assigned to the process instance - must be unique
	 * @return process instance IDentifier
	 * @throws RuntimeException in case of encountered errors
	 * @throws DeploymentNotFoundException in case a deployment with the given deployment identifier does not exist
     * @throws DeploymentNotActiveException in case the deployment with the given deployment identifier is not active
	 */
	Long startProcess(String deploymentId, String processId, CorrelationKey correlationKey);

	/**
	 * Starts a process, sets variables, and assigns a correlation key
	 *
	 * @param deploymentId deployment identifier
	 * @param processId process identifier
	 * @param correlationKey correlation key to be assigned to the process instance - must be unique
	 * @param params process variables
	 * @return process instance IDentifier
	 * @throws RuntimeException in case of encountered errors
	 * @throws DeploymentNotFoundException in case a deployment with the given deployment identifier does not exist
     * @throws DeploymentNotActiveException in case the deployment with the given deployment identifier is not active
	 */
    Long startProcess(String deploymentId, String processId, CorrelationKey correlationKey, Map<String, Object> params);

	  /**
	   * Run a process that is designed to start and finish in a single transaction.
	   * This method starts the process and returns when the process completes.
	   * It returns the state of process variables at the outcome of the process
	   *
	   * @param deploymentId deployment identifier for the KJAR file of the process
	   * @param processId process identifier
	   * @param params process variables
	   * @return the state of process variables at the end of the process
	   */
	     Map<String, Object> computeProcessOutcome(String deploymentId, String processId, Map<String, Object> params);

    /**
     * Starts a process at the listed nodes, instead of the normal starting point.
     * This method can be used for restarting a process that was aborted. However,
     * it does not restore the context of a previous process instance. You must
     * supply all necessary variables when calling this method.
     * This method does not guarantee that the process is started in a valid state.
     *
     * @param deploymentId deployment identifier
     * @param processId process identifier
     * @param params process variables
     * @param nodeIds list of BPMN node identifiers where the process must start
     * @return process instance IDentifier
     * @throws RuntimeException in case of encountered errors
     * @throws DeploymentNotFoundException in case a deployment with the given deployment identifier does not exist
     * @throws DeploymentNotActiveException in case the deployment with the given deployment identifier is not active
     */
    Long startProcessFromNodeIds(String deploymentId, String processId, Map<String, Object> params, String... nodeIds);

    /**
    * Starts a process at the listed nodes, instead of the normal starting point,
    * and assigns a correlation key.
    * This method can be used for restarting a process that was aborted. However,
    * it does not restore the context of a previous process instance. You must
    * supply all necessary variables when calling this method.
    * This method does not guarantee that the process is started in a valid state.
     *
     * @param deploymentId deployment identifier
     * @param processId process identifier
     * @param key correlation key (must be unique)
     * @param params process variables
     * @param nodeIds list of BPMN node identifiers where the process must start.
     * @return process instance IDentifier
     * @throws RuntimeException in case of encountered errors
     * @throws DeploymentNotFoundException in case a deployment with the given deployment identifier does not exist
     * @throws DeploymentNotActiveException in case the deployment with the given deployment identifier is not active
     */
    Long startProcessFromNodeIds(String deploymentId, String processId, CorrelationKey key, Map<String, Object> params, String... nodeIds);

    /**
     * Aborts the specified process
     *
     * @param processInstanceId process instance unique identifier
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    void abortProcessInstance(Long processInstanceId);

    /**
     * Aborts the specified process
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId process instance unique identifier
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    void abortProcessInstance(String deploymentId, Long processInstanceId);

    /**
	 * Aborts all specified processes
	 *
	 * @param processInstanceIds list of process instance unique identifiers
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
	 */
    void abortProcessInstances(List<Long> processInstanceIds);

    /**
     * Aborts all specified processes
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceIds list of process instance unique identifiers
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    void abortProcessInstances(String deploymentId, List<Long> processInstanceIds);

    /**
	 * Signals an event to a single process instance
	 *
	 * @param processInstanceId the process instance unique identifier
	 * @param signalName the ID of the signal in the process
	 * @param event the event object to be passed with the event
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
	 */
    void signalProcessInstance(Long processInstanceId, String signalName, Object event);

    /**
     * Signals an event to a single process instance
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId the process instance unique identifier
     * @param signalName the ID of the signal in the process
     * @param event the event object to be passed with the event
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    void signalProcessInstance(String deploymentId, Long processInstanceId, String signalName, Object event);

    /**
	 * Signal an event to a list of process instances
	 *
	 * @param processInstanceIds list of process instance unique identifiers
	 * @param signalName the ID of the signal in the process
	 * @param event the event object to be passed with the event
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
	 */
    void signalProcessInstances(List<Long> processInstanceIds, String signalName, Object event);

    /**
     * Signal an event to a list of process instances
     *
     * @param deploymentId deployment to which the process instances belong
     * @param processInstanceIds list of process instance unique identifiers
     * @param signalName the ID of the signal in the process
     * @param event the event object to be passed with the event
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    void signalProcessInstances(String deploymentId, List<Long> processInstanceIds, String signalName, Object event);

		/**
     * Signal an event to a single process instance by correlation key
     *
     * @param correlationKey the unique correlation key of the process instance
     * @param signalName the ID of the signal in the process
     * @param event the event object to be passed in with the event
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given key was not found
     */
    void signalProcessInstanceByCorrelationKey(CorrelationKey correlationKey, String signalName, Object event);

		/**
		 * Signal an event to a single process instance by correlation key
		 *
		 * @param deploymentId deployment to which the process instance belongs
		 * @param correlationKey the unique correlation key of the process instance
		 * @param signalName the ID of the signal in the process
		 * @param event the event object to be passed in with the event
		 * @throws DeploymentNotFoundException in case the deployment unit was not found
		 * @throws ProcessInstanceNotFoundException in case a process instance with the given key was not found
		 */
		void signalProcessInstanceByCorrelationKey(String deploymentId, CorrelationKey correlationKey, String signalName, Object event);

		/**
		 * Signal an event to given list of correlation keys
		 *
		 * @param correlationKeys list of unique correlation keys of process instances
		 * @param signalName the ID of the signal in the process
		 * @param event the event object to be passed in with the event
		 * @throws DeploymentNotFoundException in case the deployment unit was not found
		 * @throws ProcessInstanceNotFoundException in case a process instance with one of the given keys was not found
		 */
		void signalProcessInstancesByCorrelationKeys(List<CorrelationKey> correlationKeys, String signalName, Object event);

		/**
		 * Signal an event to given list of correlation keys
		 *
		 * @param deploymentId deployment to which the process instances belong
		 * @param correlationKeys list of unique correlation keys of process instances
		 * @param signalName the ID of the signal in the process
		 * @param event the event object to be passed in with the event
		 * @throws DeploymentNotFoundException in case the deployment unit was not found
		 * @throws ProcessInstanceNotFoundException in case a process instance with one of the given keys was not found
		 */
		void signalProcessInstancesByCorrelationKeys(String deploymentId, List<CorrelationKey> correlationKeys, String signalName, Object event);

    /**
     * Signal an event to a any process instance that listens to a given signal and belongs to a given deployment
     *
     * @param deployment identifier of the deployment
     * @param signalName the ID of the signal in the process
     * @param event the event object to be passed with the event
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     */
    void signalEvent(String deployment, String signalName, Object event);

    /**
	 * Returns process instance information. Will return null if no
	 * active process with the ID is found
	 *
	 * @param processInstanceId The process instance unique identifier
	 * @return Process instance information
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 */
    ProcessInstance getProcessInstance(Long processInstanceId);

    /**
     * Returns process instance information. Will return null if no
     * active process with the ID is found
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId The process instance unique identifier
     * @return Process instance information
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     */
    ProcessInstance getProcessInstance(String deploymentId, Long processInstanceId);

    /**
	 * Returns process instance information. Will return null if no
	 * active process with that correlation key is found
	 *
	 * @param correlationKey correlation key assigned to the process instance
	 * @return Process instance information
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 */
    ProcessInstance getProcessInstance(CorrelationKey correlationKey);

    /**
     * Returns process instance information. Will return null if no
     * active process with that correlation key is found
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param correlationKey correlation key assigned to the process instance
     * @return Process instance information
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     */
    ProcessInstance getProcessInstance(String deploymentId, CorrelationKey correlationKey);

    /**
	 * Sets a process variable.
	 * @param processInstanceId The process instance unique identifier
	 * @param variableId The variable ID to set
	 * @param value The variable value
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
	 */
    void setProcessVariable(Long processInstanceId, String variableId, Object value);

    /**
     * Sets a process variable.
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId The process instance unique identifier
     * @param variableId The variable id to set.
     * @param value The variable value.
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    void setProcessVariable(String deploymentId, Long processInstanceId, String variableId, Object value);

    /**
	 * Sets process variables.
	 *
	 * @param processInstanceId The process instance unique identifier
	 * @param variables map of process variables (key = variable name, value = variable value)
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
	 */
    void setProcessVariables(Long processInstanceId, Map<String, Object> variables);

    /**
     * Sets process variables.
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId The process instance unique identifier
     * @param variables map of process variables (key = variable name, value = variable value)
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    void setProcessVariables(String deploymentId, Long processInstanceId, Map<String, Object> variables);

    /**
	 * Gets a process instance variable.
	 *
	 * @param processInstanceId the process instance unique identifier
	 * @param variableName the variable name to get from the process
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
	*/
    Object getProcessInstanceVariable(Long processInstanceId, String variableName);

    /**
     * Gets a process instance variable.
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId the process instance unique identifier
     * @param variableName the variable name to get from the process
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
    */
    Object getProcessInstanceVariable(String deploymentId, Long processInstanceId, String variableName);

	/**
	 * Gets a process instance variable values.
	 *
	 * @param processInstanceId The process instance unique identifier
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
	 * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
	*/
	Map<String, Object> getProcessInstanceVariables(Long processInstanceId);

	/**
     * Gets a process instance variable values.
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId The process instance unique identifier
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
    */
    Map<String, Object> getProcessInstanceVariables(String deploymentId, Long processInstanceId);

	/**
	 * Returns all signals available in current state of given process instance
	 *
	 * @param processInstanceId process instance ID
	 * @return list of available signals or empty list if no signals are available
	 */
    Collection<String> getAvailableSignals(Long processInstanceId);

    /**
     * Returns all signals available in current state of given process instance
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId process instance ID
     * @return list of available signals or empty list if no signals are available
     */
    Collection<String> getAvailableSignals(String deploymentId, Long processInstanceId);

	/**
	 * Completes the specified WorkItem with the given results
	 *
	 * @param id workItem ID
	 * @param results results of the workItem
	 * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws WorkItemNotFoundException in case a work item with the given ID was not found
	 */
    void completeWorkItem(Long id, Map<String, Object> results);

    /**
     * Completes the specified WorkItem with the given results
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId process instance ID to which the work item belongs
     * @param id workItem ID
     * @param results results of the workItem
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws WorkItemNotFoundException in case a work item with the given ID was not found
     */
    void completeWorkItem(String deploymentId, Long processInstanceId, Long id, Map<String, Object> results);

    /**
     * Abort the specified workItem
     *
     * @param id workItem ID
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws WorkItemNotFoundException in case a work item with the given ID was not found
     */
    void abortWorkItem(Long id);

    /**
     * Abort the specified workItem
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId process instance ID to which the work item belongs
     * @param id workItem ID
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws WorkItemNotFoundException in case a work item with the given ID was not found
     */
    void abortWorkItem(String deploymentId, Long processInstanceId, Long id);

    /**
     * Returns the specified workItem
     *
     * @param id workItem ID
     * @return The specified workItem
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws WorkItemNotFoundException in case a work item with the given ID was not found
     */
    WorkItem getWorkItem(Long id);

    /**
     * Returns the specified workItem
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId process instance ID to which the work item belongs
     * @param id workItem ID
     * @return The specified workItem
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws WorkItemNotFoundException in case a work item with the given ID was not found
     */
    WorkItem getWorkItem(String deploymentId, Long processInstanceId, Long id);

    /**
     * Returns active work items by process instance ID.
     *
     * @param processInstanceId process instance ID
     * @return The list of active workItems for the process instance
     * @throws DeploymentNotFoundException in case the deployment unit was not found
	 * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    List<WorkItem> getWorkItemByProcessInstance(Long processInstanceId);

    /**
     * Returns active work items by process instance ID.
     *
     * @param deploymentId deployment to which the process instance belongs
     * @param processInstanceId process instance ID
     * @return The list of active workItems for the process instance
     * @throws DeploymentNotFoundException in case the deployment unit was not found
     * @throws ProcessInstanceNotFoundException in case a process instance with the given ID was not found
     */
    List<WorkItem> getWorkItemByProcessInstance(String deploymentId, Long processInstanceId);


    /**
     * Executes the provided command on the underlying command executor (usually KieSession)
     * @param deploymentId deployment identifier
     * @param command actual command for execution
     * @return results of the command execution
     * @throws DeploymentNotFoundException in case a deployment with the given deployment identifier does not exist
     * @throws DeploymentNotActiveException in case the deployment with the given deployment identifier is not active for restricted commands (for example, start process)
     */
    public <T> T execute(String deploymentId, Command<T> command);

    /**
     * Executes the provided command on the underlying command executor (usually KieSession)
     * @param deploymentId deployment identifier
     * @param context context implementation to be used to get the runtime engine
     * @param command actual command for execution
     * @return results of the command execution
     * @throws DeploymentNotFoundException in case a deployment with the given deployment identifier does not exist
     * @throws DeploymentNotActiveException in case the deployment with the given deployment identifier is not active for restricted commands (for example, start process)
     */
    public <T> T execute(String deploymentId, Context<?> context, Command<T> command);

}

66.3.5. Runtime Data Service

You can use the runtime data service to retrieve all runtime information about processes, such as started process instances and executed node instances.

For example, you can build a list-based UI to show process definitions, process instances, tasks for a given user, and other data, based on information provided by the runtime data service.

This service is optimized to be as efficient as possible while providing all required information.

The following examples show various usage of this service.

Retrieving all process definitions

Collection definitions = runtimeDataService.getProcesses(new QueryContext());

Retrieving active process instances

Collection<processinstancedesc> instances = runtimeDataService.getProcessInstances(new QueryContext());

Retrieving active nodes for a particular process instance

Collection<nodeinstancedesc> instances = runtimeDataService.getProcessInstanceHistoryActive(processInstanceId, new QueryContext());

Retrieving tasks assigned to the user john

List<tasksummary> taskSummaries = runtimeDataService.getTasksAssignedAsPotentialOwner("john", new QueryFilter(0, 10));

The runtime data service methods support two important parameters, QueryContext and QueryFilter. QueryFilter is an extension of QueryContext. You can use these parameters to manage the result set, providing pagination, sorting, and ordering. You can also use them to apply additional filtering when searching for user tasks.

The following definition shows the methods of the RuntimeDataService interface:

Definition of the RuntimeDataService interface

public interface RuntimeDataService {
	/**
	 * Represents type of node instance log entries
	 *
	 */
	enum EntryType {

        START(0),
        END(1),
        ABORTED(2),
        SKIPPED(3),
        OBSOLETE(4),
        ERROR(5);
	}

    // Process instance information

    /**
     * Returns a list of process instance descriptions
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the available process instances
     */
    Collection<ProcessInstanceDesc> getProcessInstances(QueryContext queryContext);

    /**
     * Returns a list of all process instance descriptions with the given statuses and initiated by <code>initiator</code>
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have
     * @param initiator the initiator of the {@link ProcessInstance}
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that match
     *         the given criteria (states and initiator)
     */
    Collection<ProcessInstanceDesc> getProcessInstances(List<Integer> states, String initiator, QueryContext queryContext);

    /**
     * Returns a list of process instance descriptions found for the given process ID and statuses and initiated by <code>initiator</code>
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have
     * @param processId ID of the {@link Process} (definition) used when starting the process instance
     * @param initiator initiator of the {@link ProcessInstance}
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that match
     *         the given criteria (states, processId, and initiator)
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByProcessId(List<Integer> states, String processId, String initiator, QueryContext queryContext);

    /**
    * Returns a list of process instance descriptions found for the given process name and statuses and initiated by <code>initiator</code>
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have
     * @param processName name (not ID) of the {@link Process} (definition) used when starting the process instance
     * @param initiator initiator of the {@link ProcessInstance}
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that match
     *         the given criteria (states, processName and initiator)
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByProcessName(List<Integer> states, String processName, String initiator, QueryContext queryContext);

    /**
     * Returns a list of process instance descriptions found for the given deployment ID and statuses
     * @param deploymentId deployment ID of the runtime
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that match
     *         the given criteria (deploymentId and states)
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByDeploymentId(String deploymentId, List<Integer> states, QueryContext queryContext);

    /**
     * Returns process instance descriptions found for the given processInstanceId. If no descriptions are found, null is returned. At the same time, the method
     * fetches all active tasks (in status: Ready, Reserved, InProgress) to provide the information about what user task is keeping each instance
     * and who owns the task (if the task is already claimed by a user)
     * @param processInstanceId ID of the process instance to be fetched
     * @return process instance information, in the form of a {@link ProcessInstanceDesc} instance
     */
    ProcessInstanceDesc getProcessInstanceById(long processInstanceId);

    /**
     * Returns the active process instance description found for the given correlation key. If none is found, returns null. At the same time it
     * fetches all active tasks (in status: Ready, Reserved, InProgress) to provide information about which user task is keeping each instance
     * and who owns the task (if the task is already claimed by a user)
     * @param correlationKey correlation key assigned to the process instance
     * @return process instance information, in the form of a {@link ProcessInstanceDesc} instance
     */
    ProcessInstanceDesc getProcessInstanceByCorrelationKey(CorrelationKey correlationKey);

    /**
     * Returns process instances descriptions (regardless of their states) found for the given correlation key. If no descriptions are found, an empty list is returned
     * This query uses 'LIKE' to match correlation keys so it accepts partial keys. Matching
     * is performed based on a 'starts with' criterion
     * @param correlationKey correlation key assigned to the process instance
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that match
     *         the given correlation key
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByCorrelationKey(CorrelationKey correlationKey, QueryContext queryContext);

    /**
     * Returns process instance descriptions, filtered by their states, that were found for the given correlation key. If none are found, returns an empty list
     * This query uses 'LIKE' to match correlation keys so it accepts partial keys. Matching
     * is performed based on a 'starts with' criterion
     * @param correlationKey correlation key assigned to process instance
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that match
     *         the given correlation key
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByCorrelationKeyAndStatus(CorrelationKey correlationKey, List<Integer> states, QueryContext queryContext);

    /**
     * Returns a list of process instance descriptions found for the given process definition ID
     * @param processDefId ID of the process definition
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that match
     *         the given criteria (deploymentId and states)
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByProcessDefinition(String processDefId, QueryContext queryContext);

    /**
     * Returns a list of process instance descriptions found for the given process definition ID, filtered by state
     * @param processDefId ID of the process definition
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that match
     *         the given criteria (deploymentId and states)
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByProcessDefinition(String processDefId, List<Integer> states, QueryContext queryContext);

    /**
     * Returns process instance descriptions that match process instances that have the given variable defined, filtered by state
     * @param variableName name of the variable that process instance should have
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have. If null, returns only active instances
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that have the given variable defined
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByVariable(String variableName, List<Integer> states, QueryContext queryContext);

    /**
     * Returns process instance descriptions that match process instances that have the given variable defined and the value of the variable matches the given variableValue
     * @param variableName name of the variable that process instance should have
     * @param variableValue value of the variable to match
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have. If null, returns only active instances
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the process instances that have the given variable defined with the given value
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByVariableAndValue(String variableName, String variableValue, List<Integer> states, QueryContext queryContext);

    /**
     * Returns a list of process instance descriptions that have the specified parent
     * @param parentProcessInstanceId ID of the parent process instance
     * @param states list of possible state (int) values that the {@link ProcessInstance} can have. If null, returns only active instances
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessInstanceDesc} instances representing the available process instances
     */
    Collection<ProcessInstanceDesc> getProcessInstancesByParent(Long parentProcessInstanceId, List<Integer> states, QueryContext queryContext);

    /**
     * Returns a list of process instance descriptions that are subprocesses of the specified process, or subprocesses of those subprocesses, and so on. The list includes the full hierarchy of subprocesses under the specified parent process
     * @param processInstanceId ID of the parent process instance
     * @return list of {@link ProcessInstanceDesc} instances representing the full hierarchy of this process
     */
    Collection<ProcessInstanceDesc> getProcessInstancesWithSubprocessByProcessInstanceId(Long processInstanceId, List<Integer> states, QueryContext queryContext);

    // Node and Variable instance information

    /**
     * Returns the active node instance descriptor for the given work item ID, if the work item exists and is active
     * @param workItemId identifier of the work item
     * @return NodeInstanceDesc for work item if it exists and is still active, otherwise null is returned
     */
    NodeInstanceDesc getNodeInstanceForWorkItem(Long workItemId);

    /**
     * Returns a trace of all active nodes for the given process instance ID
     * @param processInstanceId unique identifier of the process instance
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return
     */
    Collection<NodeInstanceDesc> getProcessInstanceHistoryActive(long processInstanceId, QueryContext queryContext);

    /**
     * Returns a trace of all executed (completed) nodes for the given process instance ID
     * @param processInstanceId unique identifier of the process instance
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return
     */
    Collection<NodeInstanceDesc> getProcessInstanceHistoryCompleted(long processInstanceId, QueryContext queryContext);

    /**
     * Returns a complete trace of all executed (completed) and active nodes for the given process instance ID
     * @param processInstanceId unique identifier of the process instance
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return {@link NodeInstance} information, in the form of a list of {@link NodeInstanceDesc} instances,
     *         that come from a process instance that matches the given criteria (deploymentId, processId)
     */
    Collection<NodeInstanceDesc> getProcessInstanceFullHistory(long processInstanceId, QueryContext queryContext);

    /**
     * Returns a complete trace of all events of the given type (START, END, ABORTED, SKIPPED, OBSOLETE or ERROR) for the given process instance
     * @param processInstanceId unique identifier of the process instance
     * @param queryContext control parameters for the result, such as sorting and paging
     * @param type type of events to be returned (START, END, ABORTED, SKIPPED, OBSOLETE or ERROR). To return all events, use {@link #getProcessInstanceFullHistory(long, QueryContext)}
     * @return collection of node instance descriptions
     */
    Collection<NodeInstanceDesc> getProcessInstanceFullHistoryByType(long processInstanceId, EntryType type, QueryContext queryContext);


    /**
     * Returns a trace of all nodes for the given node types and process instance ID
     * @param processInstanceId unique identifier of the process instance
     * @param nodeTypes list of node types to filter nodes of the process instance
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return collection of node instance descriptions
     */
    Collection<NodeInstanceDesc> getNodeInstancesByNodeType(long processInstanceId, List<String> nodeTypes, QueryContext queryContext);

    /**
     * Returns a trace of all nodes for the given node types and correlation key
     * @param correlationKey correlation key
     * @param states list of states
     * @param nodeTypes list of node types to filter nodes of process instance
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return collection of node instance descriptions
     */
    Collection<NodeInstanceDesc> getNodeInstancesByCorrelationKeyNodeType(CorrelationKey correlationKey,  List<Integer> states, List<String> nodeTypes, QueryContext queryContext);


    /**
     * Returns a collection of all process variables and their current values for the given process instance
     * @param processInstanceId process instance ID
     * @return information about variables in the specified process instance,
     *         represented by a list of {@link VariableDesc} instances
     */
    Collection<VariableDesc> getVariablesCurrentState(long processInstanceId);

    /**
     * Returns a collection of changes to the given variable within the scope of a process instance
     * @param processInstanceId unique identifier of the process instance
     * @param variableId ID of the variable
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return information about the variable with the given ID in the specified process instance,
     *         represented by a list of {@link VariableDesc} instances
     */
    Collection<VariableDesc> getVariableHistory(long processInstanceId, String variableId, QueryContext queryContext);


    // Process information


    /**
     * Returns a list of process definitions for the given deployment ID
     * @param deploymentId deployment ID of the runtime
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessDefinition} instances representing processes that match
     *         the given criteria (deploymentId)
     */
    Collection<ProcessDefinition> getProcessesByDeploymentId(String deploymentId, QueryContext queryContext);

    /**
     * Returns a list of process definitions that match the given filter
     * @param filter regular expression
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of {@link ProcessDefinition} instances with a name or ID that matches the given regular expression
     */
    Collection<ProcessDefinition> getProcessesByFilter(String filter, QueryContext queryContext);

    /**
     * Returns all process definitions available
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of all available processes, in the form a of a list of {@link ProcessDefinition} instances
     */
    Collection<ProcessDefinition> getProcesses(QueryContext queryContext);

    /**
     * Returns a list of process definition identifiers for the given deployment ID
     * @param deploymentId deployment ID of the runtime
     * @param queryContext control parameters for the result, such as sorting and paging
     * @return list of all available process id's for a particular deployment/runtime
     */
    Collection<String> getProcessIds(String deploymentId, QueryContext queryContext);

    /**
     * Returns process definitions for the given process ID regardless of the deployment
     * @param processId ID of the process
     * @return collection of {@link ProcessDefinition} instances representing the {@link Process}
     *         with the specified process ID
     */
    Collection<ProcessDefinition> getProcessesById(String processId);

    /**
     * Returns the process definition for the given deployment and process identifiers
     * @param deploymentId ID of the deployment (runtime)
     * @param processId ID of the process
     * @return {@link ProcessDefinition} instance, representing the {@link Process}
     *         that is present in the specified deployment with the specified process ID
     */
    ProcessDefinition getProcessesByDeploymentIdProcessId(String deploymentId, String processId);

	// user task query operations

	/**
	 * Return a task by its workItemId
	 * @param workItemId
	 * @return @{@link UserTaskInstanceDesc} task
	 */
    UserTaskInstanceDesc getTaskByWorkItemId(Long workItemId);

	/**
	 * Return a task by its taskId
	 * @param taskId
	 * @return @{@link UserTaskInstanceDesc} task
	 */
	UserTaskInstanceDesc getTaskById(Long taskId);

	/**
	 * Return a task by its taskId with SLA data if the withSLA param is true
	 * @param taskId
	 * @param withSLA
	 * @return @{@link UserTaskInstanceDesc} task
	 */
	UserTaskInstanceDesc getTaskById(Long taskId, boolean withSLA);

	/**
	 * Return a list of assigned tasks for a Business Administrator user. Business
	 * administrators play the same role as task stakeholders but at task type
	 * level. Therefore, business administrators can perform the exact same
	 * operations as task stakeholders. Business administrators can also observe
	 * the progress of notifications
	 *
	 * @param userId identifier of the Business Administrator user
	 * @param filter filter for the list of assigned tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksAssignedAsBusinessAdministrator(String userId, QueryFilter filter);

	/**
     * Return a list of assigned tasks for a Business Administrator user for with one of the listed
     * statuses
     * @param userId identifier of the Business Administrator user
     * @param statuses the statuses of the tasks to return
     * @param filter filter for the list of assigned tasks
     * @return list of @{@link TaskSummary} task summaries
     */
	List<TaskSummary> getTasksAssignedAsBusinessAdministratorByStatus(String userId, List<Status> statuses, QueryFilter filter);

	/**
	 * Return a list of tasks that a user is eligible to own
	 *
	 * @param userId identifier of the user
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksAssignedAsPotentialOwner(String userId, QueryFilter filter);

	/**
	 * Return a list of tasks the user or user groups are eligible to own
	 *
	 * @param userId identifier of the user
	 * @param groupIds a list of identifiers of the groups
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksAssignedAsPotentialOwner(String userId, List<String> groupIds, QueryFilter filter);

	/**
	 * Return a list of tasks the user is eligible to own and that are in one of the listed
	 * statuses
	 *
	 * @param userId identifier of the user
	 * @param status filter for the task statuses
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksAssignedAsPotentialOwnerByStatus(String userId, List<Status> status, QueryFilter filter);

	/**
	 * Return a list of tasks the user or groups are eligible to own and that are in one of the listed
	 * statuses
	 * @param userId identifier of the user
	 * @param groupIds filter for the identifiers of the groups
	 * @param status filter for the task statuses
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksAssignedAsPotentialOwner(String userId, List<String> groupIds, List<Status> status, QueryFilter filter);

	/**
	 * Return a list of tasks the user is eligible to own, that are in one of the listed
	 * statuses, and that have an expiration date starting at <code>from</code>. Tasks that do not have expiration date set
	 * will also be included in the result set
	 *
	 * @param userId identifier of the user
	 * @param status filter for the task statuses
	 * @param from earliest expiration date for the tasks
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksAssignedAsPotentialOwnerByExpirationDateOptional(String userId, List<Status> status, Date from, QueryFilter filter);

	/**
	 * Return a list of tasks the user has claimed, that are in one of the listed
	 * statuses, and that have an expiration date starting at <code>from</code>. Tasks that do not have expiration date set
	 * will also be included in the result set
	 *
	 * @param userId identifier of the user
	 * @param strStatuses filter for the task statuses
	 * @param from earliest expiration date for the tasks
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksOwnedByExpirationDateOptional(String userId, List<Status> strStatuses, Date from, QueryFilter filter);

	/**
	 * Return a list of tasks the user has claimed
	 *
	 * @param userId identifier of the user
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksOwned(String userId, QueryFilter filter);

	/**
	 * Return a list of tasks the user has claimed with one of the listed
	 * statuses
	 *
	 * @param userId identifier of the user
	 * @param status filter for the task statuses
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksOwnedByStatus(String userId, List<Status> status, QueryFilter filter);

	/**
	 * Get a list of tasks the Process Instance is waiting on
	 *
	 * @param processInstanceId identifier of the process instance
	 * @return list of task identifiers
	 */
	List<Long> getTasksByProcessInstanceId(Long processInstanceId);

	/**
	 * Get filter for the tasks the Process Instance is waiting on that are in one of the
	 * listed statuses
	 *
	 * @param processInstanceId identifier of the process instance
	 * @param status filter for the task statuses
	 * @param filter filter for the list of tasks
	 * @return list of @{@link TaskSummary} task summaries
	 */
	List<TaskSummary> getTasksByStatusByProcessInstanceId(Long processInstanceId, List<Status> status, QueryFilter filter);

    /**
	 * Get a list of task audit logs for all tasks owned by the user, applying a query filter to the list of tasks
	 *
	 *
	 * @param userId identifier of the user that owns the tasks
	 * @param filter filter for the list of tasks
	 * @return list of @{@link AuditTask} task audit logs
	 */
    List<AuditTask> getAllAuditTask(String userId, QueryFilter filter);

    /**
		* Get a list of task audit logs for all tasks that are active and owned by the user, applying a query filter to the list of tasks
	 *
	 * @param userId identifier of the user that owns the tasks
	 * @param filter filter for the list of tasks
	 * @return list of @{@link AuditTask} audit tasks
	 */
    List<AuditTask> getAllAuditTaskByStatus(String userId, QueryFilter filter);

    /**
	 * Get a list of task audit logs for group tasks (actualOwner == null) for the user, applying a query filter to the list of tasks
	 *
	 * @param userId identifier of the user that is associated with the group tasks
	 * @param filter filter for the list of tasks
	 * @return list of @{@link AuditTask} audit tasks
	 */
    List<AuditTask> getAllGroupAuditTask(String userId, QueryFilter filter);


    /**
	 * Get a list of task audit logs for tasks that are assigned to a Business Administrator user, applying a query filter to the list of tasks
	 *
	 * @param userId identifier of the Business Administrator user
	 * @param filter filter for the list of tasks
	 * @return list of @{@link AuditTask} audit tasks
	 */
    List<AuditTask> getAllAdminAuditTask(String userId, QueryFilter filter);

    /**
     * Gets a list of task events for the given task
     * @param taskId identifier of the task
     * @param filter for the list of events
	 * @return list of @{@link TaskEvent} task events
     */
    List<TaskEvent> getTaskEvents(long taskId, QueryFilter filter);

    /**
     * Query on {@link TaskSummary} instances
     * @param userId the user associated with the tasks queried
     * @return {@link TaskSummaryQueryBuilder} used to create the query
     */
    TaskSummaryQueryBuilder taskSummaryQuery(String userId);

    /**
     * Gets a list of {@link TaskSummary} instances for tasks that define a given variable
     * @param userId the ID of the user associated with the tasks
     * @param variableName the name of the task variable
     * @param statuses the list of statuses that the task can have
     * @param queryContext the query context
     * @return a {@link List} of {@link TaskSummary} instances
     */
    List<TaskSummary> getTasksByVariable(String userId, String variableName, List<Status> statuses, QueryContext queryContext);

    /**
     * Gets a list of {@link TaskSummary} instances for tasks that define a given variable and the variable is set to the given value
     * @param userId the ID of the user associated with the tasks
     * @param variableName the name of the task variable
     * @param variableValue the value of the task variable
     * @param statuses the list of statuses that the task can have
     * @param context the query context
     * @return a {@link List} of {@link TaskSummary} instances
     */
    List<TaskSummary> getTasksByVariableAndValue(String userId, String variableName, String variableValue, List<Status> statuses, QueryContext context);

}

66.3.6. User Task Service

The user task service covers the complete lifecycle of an individual task, and you can use the service to manage a user task from start to end.

Task queries are not a part of the user task service. Use the runtime data service to query for tasks. Use the user task service for scoped operations on one task, including the following actions:

Modification of selected properties
Access to task variables
Access to task attachments
Access to task comments

The user task service is also a command executor. You can use it to execute custom task commands.

The following example shows starting a process and interacting with a task in the process:

Starting a process and interacting with a user task in this process

long processInstanceId =
processService.startProcess(deployUnit.getIdentifier(), "org.jbpm.writedocument");

List<Long> taskIds =
runtimeDataService.getTasksByProcessInstanceId(processInstanceId);

Long taskId = taskIds.get(0);

userTaskService.start(taskId, "john");
UserTaskInstanceDesc task = runtimeDataService.getTaskById(taskId);

Map<String, Object> results = new HashMap<String, Object>();
results.put("Result", "some document data");
userTaskService.complete(taskId, "john", results);

66.3.7. Quartz-based timer service

The process engine provides a cluster-ready timer service using Quartz. You can use the service to dispose or load your KIE session at any time. The service can manage how long a KIE session is active in order to fire each timer appropriately.

The following example shows a basic Quartz configuration file for a clustered environment:

Quartz configuration file for a clustered environment

#============================================================================
# Configure Main Scheduler Properties
#============================================================================

org.quartz.scheduler.instanceName = jBPMClusteredScheduler
org.quartz.scheduler.instanceId = AUTO

#============================================================================
# Configure ThreadPool
#============================================================================

org.quartz.threadPool.class = org.quartz.simpl.SimpleThreadPool
org.quartz.threadPool.threadCount = 5
org.quartz.threadPool.threadPriority = 5

#============================================================================
# Configure JobStore
#============================================================================

org.quartz.jobStore.misfireThreshold = 60000

org.quartz.jobStore.class=org.quartz.impl.jdbcjobstore.JobStoreCMT
org.quartz.jobStore.driverDelegateClass=org.quartz.impl.jdbcjobstore.StdJDBCDelegate
org.quartz.jobStore.useProperties=false
org.quartz.jobStore.dataSource=managedDS
org.quartz.jobStore.nonManagedTXDataSource=nonManagedDS
org.quartz.jobStore.tablePrefix=QRTZ_
org.quartz.jobStore.isClustered=true
org.quartz.jobStore.clusterCheckinInterval = 20000

#=========================================================================
# Configure Datasources
#=========================================================================
org.quartz.dataSource.managedDS.jndiURL=jboss/datasources/psbpmsDS
org.quartz.dataSource.nonManagedDS.jndiURL=jboss/datasources/quartzNonManagedDS

You must modify the previous example to fit your environment.

66.3.8. Query service

The query service provides advanced search capabilities that are based on Dashbuilder data sets.

With this approach, you can control how to retrieve data from underlying data store. You can use complex JOIN statements with external tables such as JPA entities tables or custom systems database tables.

The query service is built around the following two sets of operations:

Management operations:
- Register a query definition
- Replace a query definition
- Unregister (remove) a query definition
- Get a query definition
- Get all registered query definitions
Runtime operations:
- Simple query based on QueryParam as the filter provider
- Advanced query based on QueryParamBuilder as the filter provider

Dashbuilder data sets provide support for multiple data sources, such as CSV, SQL, and Elastic Search. However, the process engine uses a RDBMS-based backend and focuses on SQL-based data sets.

Therefore, the process engine query service is a subset of Dashbuilder data set capabilities that enables efficient queries with a simple API.

66.3.8.1. Key classes of the query service

The query service relies on the following key classes:

QueryDefinition: Represents the definition of a data set. The definition consists of a unique name, an SQL expression (the query) and the source, the JNDI name of the data source to use when performing queries.
QueryParam: The basic structure that represents an individual query parameter or condition. This structure consists of the column name, operator, and expected values.
QueryResultMapper: The class that maps raw dataset data (rows and columns) to an object representation.
QueryParamBuilder: The class that builds query filters that are applied to the query definition to invoke the query.

QueryResultMapper

QueryResultMapper maps data taken from a database (dataset) to an object representation. It is similar to ORM providers such as hibernate, which map tables to entities.

Many object types can be used for representing dataset results. Therefore, existing mappers might not always suit your needs. Mappers in QueryResultMapper are pluggable and you can provide your own mapper when necessary, in order to transform dataset data into any type you need.

The process engine supplies the following mappers:

org.jbpm.kie.services.impl.query.mapper.ProcessInstanceQueryMapper, registered with the name ProcessInstances
org.jbpm.kie.services.impl.query.mapper.ProcessInstanceWithVarsQueryMapper, registered with the name ProcessInstancesWithVariables
org.jbpm.kie.services.impl.query.mapper.ProcessInstanceWithCustomVarsQueryMapper, registered with the name ProcessInstancesWithCustomVariables
org.jbpm.kie.services.impl.query.mapper.UserTaskInstanceQueryMapper, registered with the name UserTasks
org.jbpm.kie.services.impl.query.mapper.UserTaskInstanceWithVarsQueryMapper, registered with the name UserTasksWithVariables
org.jbpm.kie.services.impl.query.mapper.UserTaskInstanceWithCustomVarsQueryMapper, registered with name UserTasksWithCustomVariables
org.jbpm.kie.services.impl.query.mapper.TaskSummaryQueryMapper, registered with the name TaskSummaries
org.jbpm.kie.services.impl.query.mapper.RawListQueryMapper, registered with the name RawList

Each QueryResultMapper is registered with a unique string name. You can look up mappers by this name instead of referencing the full class name. This feature is especially important when using EJB remote invocation of services, because it avoids relying on a particular implementation on the client side.

To reference a QueryResultMapper by the string name, use NamedQueryMapper, which is a part of the jbpm-services-api module. This class acts as a delegate (lazy delegate) and looks up the actual mapper when the query is performed.

Using NamedQueryMapper

queryService.query("my query def", new NamedQueryMapper<Collection<ProcessInstanceDesc>>("ProcessInstances"), new QueryContext());

QueryParamBuilder

QueryParamBuilder provides an advanced way of building filters for data sets.

By default, when you use a query method of QueryService that accepts zero or more QueryParam instances, all of these parameters are joined with an AND operator, so a data entry must match all of them.

However, sometimes more complicated relationships between parameters are required. You can use QueryParamBuilder to build custom builders that provide filters at the time the query is issued.

One existing implementation of QueryParamBuilder is available in the process engine. It covers default QueryParams that are based on the core functions.

These core functions are SQL-based conditions, including the following conditions:

IS_NULL
NOT_NULL
EQUALS_TO
NOT_EQUALS_TO
LIKE_TO
GREATER_THAN
GREATER_OR_EQUALS_TO
LOWER_THAN
LOWER_OR_EQUALS_TO
BETWEEN
IN
NOT_IN

Before invoking a query, the process engine invokes the build method of the QueryParamBuilder interface as many times as necessary while the method returns a non-null value. Because of this approach, you can build up complex filter options that could not be expressed by a simple list of QueryParams.

The following example shows a basic implementation of QueryParamBuilder. It relies on the DashBuilder Dataset API.

Basic implementation of QueryParamBuilder

public class TestQueryParamBuilder implements QueryParamBuilder<ColumnFilter> {

    private Map<String, Object> parameters;
    private boolean built = false;
    public TestQueryParamBuilder(Map<String, Object> parameters) {
        this.parameters = parameters;
    }

    @Override
    public ColumnFilter build() {
        // return null if it was already invoked
        if (built) {
            return null;
        }

        String columnName = "processInstanceId";

        ColumnFilter filter = FilterFactory.OR(
                FilterFactory.greaterOrEqualsTo((Long)parameters.get("min")),
                FilterFactory.lowerOrEqualsTo((Long)parameters.get("max")));
        filter.setColumnId(columnName);

        built = true;
        return filter;
    }

}

After implementing the builder, you can use an instance of this class when performing a query with the QueryService service, as shown in the following example:

Running a query with the QueryService service

queryService.query("my query def", ProcessInstanceQueryMapper.get(), new QueryContext(), paramBuilder);

66.3.8.2. Using the query service in a typical scenario

The following procedure outlines the typical way in which your code might use the query service.

Procedure

Define the data set, which is a view of the data you want to use. Use the QueryDefinition class in the services API to complete this operation:
Defining the data set
```
SqlQueryDefinition query = new SqlQueryDefinition("getAllProcessInstances", "java:jboss/datasources/ExampleDS");
query.setExpression("select * from processinstancelog");
```
This example represents the simplest possible query definition.
The constructor requires the following parameters:
- A unique name that identifies the query at run time
- A JNDI data source name to use for performing queries with this definition
  The parameter of the setExpression() method is the SQL statement that builds up the data set view. Queries in the query service use data from this view and filter this data as necessary.
Register the query:
Registering a query
```
queryService.registerQuery(query);
```
If required, collect all the data from the dataset, without any filtering:
Collecting all the data from the dataset
```
Collection<ProcessInstanceDesc> instances = queryService.query("getAllProcessInstances", ProcessInstanceQueryMapper.get(), new QueryContext());
```
This simple query uses defaults from QueryContext for paging and sorting.

If required, use a QueryContext object that changes the defaults of the paging and sorting:

Changing defaults using a QueryContext object

QueryContext ctx = new QueryContext(0, 100, "start_date", true);
         
Collection<ProcessInstanceDesc> instances = queryService.query("getAllProcessInstances", ProcessInstanceQueryMapper.get(), ctx);

If required, use the query to filter data:

Using a query to filter data

// single filter param
Collection<ProcessInstanceDesc> instances = queryService.query("getAllProcessInstances", ProcessInstanceQueryMapper.get(), new QueryContext(), QueryParam.likeTo(COLUMN_PROCESSID, true, "org.jbpm%"));
 
// multiple filter params (AND)
Collection<ProcessInstanceDesc> instances = queryService.query("getAllProcessInstances", ProcessInstanceQueryMapper.get(), new QueryContext(),
 QueryParam.likeTo(COLUMN_PROCESSID, true, "org.jbpm%"),
 QueryParam.in(COLUMN_STATUS, 1, 3));

With the query service, you can define what data to fetch and how to filter it. Limitation of the JPA provider or other similar limitations do not apply. You can tailor database queries to your environment to increase performance.

66.3.9. Advanced query service

The advanced query service provides capabilities to search for processes and tasks, based on process and task attributes, process variables, and internal variables of user tasks. The search automatically covers all existing processes in the process engine.

The names and required values of attributes and variables are defined in QueryParam objects.

Process attributes include process instance ID, correlation key, process definition ID, and deployment ID. Task attributes include task name, owner, and status.

The following search methods are available:

queryProcessByVariables: Search for process instances based on a list of process attributes and process variable values. To be included in the result, a process instance must have the listed attributes and the listed values in its process variables.
queryProcessByVariablesAndTask: Search for process instances based on a list of process attributes, process variable values, and task variable values. To be included in the result, a process instance must have the listed attributes and the listed values in its process variables. It also must include a task with the listed values in its task variables.
queryUserTasksByVariables: Search for user tasks based on a list of task attributes, task variable values, and process variable values. To be included in the result, a task must have the listed attributes and listed values in its task variables. It also must be included in a process with the listed values in its process variables.

The service is provided by the AdvanceRuntimeDataService class. The interface for this class also defines predefined task and process attribute names.

Definition of the AdvanceRuntimeDataService interface

public interface AdvanceRuntimeDataService {

    String TASK_ATTR_NAME = "TASK_NAME";
    String TASK_ATTR_OWNER = "TASK_OWNER";
    String TASK_ATTR_STATUS = "TASK_STATUS";
    String PROCESS_ATTR_INSTANCE_ID = "PROCESS_INSTANCE_ID";
    String PROCESS_ATTR_CORRELATION_KEY = "PROCESS_CORRELATION_KEY";
    String PROCESS_ATTR_DEFINITION_ID = "PROCESS_DEFINITION_ID";
    String PROCESS_ATTR_DEPLOYMENT_ID = "PROCESS_DEPLOYMENT_ID";
    String PROCESS_COLLECTION_VARIABLES = "ATTR_COLLECTION_VARIABLES";

    List<ProcessInstanceWithVarsDesc> queryProcessByVariables(List<QueryParam> attributes,
      List<QueryParam> processVariables, QueryContext queryContext);

    List<ProcessInstanceWithVarsDesc> queryProcessByVariablesAndTask(List<QueryParam> attributes,
       List<QueryParam> processVariables, List<QueryParam> taskVariables,
       List<String> potentialOwners, QueryContext queryContext);

    List<UserTaskInstanceWithPotOwnerDesc> queryUserTasksByVariables(List<QueryParam> attributes,
       List<QueryParam> taskVariables, List<QueryParam> processVariables,
       List<String> potentialOwners, QueryContext queryContext);
}

66.3.10. Process instance migration service

The process instance migration service is a utility for migrating process instances from one deployment to another. Process or task variables are not affected by the migration. However, the new deployment can use a different process definition.

When migrating a process, the process instance migration service also automatically migrates all the subprocesses of the process, the subprocesses of those subprocesses, and so on. If you attempt to migrate a subprocess without migrating the parent process, the migration fails.

For the simplest approach to process migration, let active process instances finish and start new process instances in the new deployment. If this approach is not suitable for your needs, consider the following issues before starting process instance migration:

Backward compatibility
Data change
Need for node mapping

Whenever possible, create backward-compatible processes by extending process definitions. For example, removing nodes from the process definition breaks compatibility. If you make such changes, you must provide node mapping. Process instance migration uses node mapping if an active process instance is in a node that has been removed.

A node map contains source node IDs from the old process definition mapped to target node IDs in the new process definition. You can map nodes of the same type only, such as a user task to a user task.

Red Hat Process Automation Manager offers several implementations of the migration service:

Methods in the ProcessInstanceMigrationService interface that implement the migration service

public interface ProcessInstanceMigrationService {
 /**
 * Migrates a given process instance that belongs to the source deployment into the target process ID that belongs to the target deployment.
 * The following rules are enforced:
 * <ul>
 * <li>the source deployment ID must point to an existing deployment</li>
 * <li>the process instance ID must point to an existing and active process instance</li>
 * <li>the target deployment must exist</li>
 * <li>the target process ID must exist in the target deployment</li>
 * </ul>
 * Returns a migration report regardless of migration being successful or not; examine the report for the outcome of the migration.
 * @param sourceDeploymentId deployment to which the process instance to be migrated belongs
 * @param processInstanceId ID of the process instance to be migrated
 * @param targetDeploymentId ID of the deployment to which the target process belongs
 * @param targetProcessId ID of the process to which the process instance should be migrated
 * @return returns complete migration report
 */
 MigrationReport migrate(String sourceDeploymentId, Long processInstanceId, String targetDeploymentId, String targetProcessId);
 /**
 * Migrates a given process instance (with node mapping) that belongs to source deployment into the target process ID that belongs to the target deployment.
 * The following rules are enforced:
 * <ul>
 * <li>the source deployment ID must point to an existing deployment</li>
 * <li>the process instance ID must point to an existing and active process instance</li>
 * <li>the target deployment must exist</li>
 * <li>the target process ID must exist in the target deployment</li>
 * </ul>
 * Returns a migration report regardless of migration being successful or not; examine the report for the outcome of the migration.
 * @param sourceDeploymentId deployment to which the process instance to be migrated belongs
 * @param processInstanceId ID of the process instance to be migrated
 * @param targetDeploymentId ID of the deployment to which the target process belongs
 * @param targetProcessId ID of the process to which the process instance should be migrated
 * @param nodeMapping node mapping - source and target unique IDs of nodes to be mapped - from process instance active nodes to new process nodes
 * @return returns complete migration report
 */
 MigrationReport migrate(String sourceDeploymentId, Long processInstanceId, String targetDeploymentId, String targetProcessId, Map<String, String> nodeMapping);
 /**
 * Migrates given process instances that belong to the source deployment into a target process ID that belongs to the target deployment.
 * The following rules are enforced:
 * <ul>
 * <li>the source deployment ID must point to an existing deployment</li>
 * <li>the process instance ID must point to an existing and active process instance</li>
 * <li>the target deployment must exist</li>
 * <li>the target process ID must exist in the target deployment</li>
 * </ul>
 * Returns a migration report regardless of migration being successful or not; examine the report for the outcome of the migration.
 * @param sourceDeploymentId deployment to which the process instances to be migrated belong
 * @param processInstanceIds list of process instance IDs to be migrated
 * @param targetDeploymentId ID of the deployment to which the target process belongs
 * @param targetProcessId ID of the process to which the process instances should be migrated
 * @return returns complete migration report
 */
 List<MigrationReport> migrate(String sourceDeploymentId, List<Long> processInstanceIds, String targetDeploymentId, String targetProcessId);
 /**
 * Migrates given process instances (with node mapping) that belong to the source deployment into a target process ID that belongs to the target deployment.
 * The following rules are enforced:
 * <ul>
 * <li>the source deployment ID must point to an existing deployment</li>
 * <li>the process instance ID must point to an existing and active process instance</li>
 * <li>the target deployment must exist</li>
 * <li>the target process ID must exist in the target deployment</li>
 * </ul>
 * Returns a migration report regardless of migration being successful or not; examine the report for the outcome of the migration.
 * @param sourceDeploymentId deployment to which the process instances to be migrated belong
 * @param processInstanceIds list of process instance ID to be migrated
 * @param targetDeploymentId ID of the deployment to which the target process belongs
 * @param targetProcessId ID of the process to which the process instances should be migrated
 * @param nodeMapping node mapping - source and target unique IDs of nodes to be mapped - from process instance active nodes to new process nodes
 * @return returns list of migration reports one per each process instance
 */
 List<MigrationReport> migrate(String sourceDeploymentId, List<Long> processInstanceIds, String targetDeploymentId, String targetProcessId, Map<String, String> nodeMapping);
}

To migrate process instances on a KIE Server, use the following implementations. These methods are similar to the methods in the ProcessInstanceMigrationService interface, providing the same migration implementations for KIE Server deployments.

Methods in the ProcessAdminServicesClient interface that implement the migration service for KIE Server deployments

public interface ProcessAdminServicesClient {

    MigrationReportInstance migrateProcessInstance(String containerId, Long processInstanceId, String targetContainerId, String targetProcessId);

    MigrationReportInstance migrateProcessInstance(String containerId, Long processInstanceId, String targetContainerId, String targetProcessId, Map<String, String> nodeMapping);

    List<MigrationReportInstance> migrateProcessInstances(String containerId, List<Long> processInstancesId, String targetContainerId, String targetProcessId);

    List<MigrationReportInstance> migrateProcessInstances(String containerId, List<Long> processInstancesId, String targetContainerId, String targetProcessId, Map<String, String> nodeMapping);
}

You can migrate a single process instance or multiple process instances at once. If you migrate multiple process instances, each instance is migrated in a separate transaction to ensure that the migrations do not affect each other.

After migration is completed, the migrate method returns a MigrationReport object that contains the following information:

The start and end dates of the migration.
The migration outcome (success or failure).
A log entry of the INFO, WARN, or ERROR type. The ERROR message terminates the migration.

The following example shows a process instance migration:

Migrating a process instance in a KIE Server deployment

import org.kie.server.api.model.admin.MigrationReportInstance;
import org.kie.server.api.marshalling.MarshallingFormat;
import org.kie.server.client.KieServicesClient;
import org.kie.server.client.KieServicesConfiguration;

public class ProcessInstanceMigrationTest{

	private static final String SOURCE_CONTAINER = "com.redhat:MigrateMe:1.0";
  private static final String SOURCE_PROCESS_ID = "MigrateMe.MigrateMev1";
	private static final String TARGET_CONTAINER = "com.redhat:MigrateMe:2";
  private static final String TARGET_PROCESS_ID = "MigrateMe.MigrateMeV2";

	public static void main(String[] args) {

		KieServicesConfiguration config = KieServicesFactory.newRestConfiguration("http://HOST:PORT/kie-server/services/rest/server", "USERNAME", "PASSWORD");
		config.setMarshallingFormat(MarshallingFormat.JSON);
		KieServicesClient client = KieServicesFactory.newKieServicesClient(config);

		long sourcePid = client.getProcessClient().startProcess(SOURCE_CONTAINER, SOURCE_PROCESS_ID);

    // Use the 'report' object to return migration results.
		MigrationReportInstance report = client.getAdminClient().migrateProcessInstance(SOURCE_CONTAINER, sourcePid,TARGET_CONTAINER, TARGET_PROCESS_ID);

		System.out.println("Was migration successful:" + report.isSuccessful());

		client.getProcessClient().abortProcessInstance(TARGET_CONTAINER, sourcePid);

	}
}

Known limitations of process instance migration

The following situations can cause a failure of the migration or incorrect migration:

A new or modified task requires inputs that are not available in the migrated process instance.
You modify the tasks prior to the active task where the changes have an impact on further processing.
You remove a human task that is currently active. To replace a human task, you must map it to another human task.
You add a new task parallel to the single active task. As all branches in an AND gateway are not activated, the process gets stuck.
You remove active timer events (these events are not changed in the database).
You fix or update inputs and outputs in an active task (the task data is not migrated).

If you apply mapping to a task node, only the task node name and description are mapped. Other task fields, including the TaskName variable, are not mapped to the new task.

66.3.11. Deployments and different process versions

The deployment service puts business assets into an execution environment. However, in some cases additional management is required to make the assets available in the correct context. Notably, if you deploy several versions of the same process, you must ensure that process instances use the correct version.

Activation and Deactivation of deployments

In some cases, a number of process instances are running on a deployment, and then you add a new version of the same process to the runtime environment.

You might decide that new instances of this process definition must use the new version while the existing active instances should continue with the previous version.

To enable this scenario, use the following methods of the deployment service:

activate: Activates a deployment so it can be available for interaction. You can list its process definitions and start new process instances for this deployment.
deactivate: Deactivates a deployment. Disables the option to list process definitions and to start new process instances of processes in the deployment. However, you can continue working with the process instances that are already active, for example, signal events and interact with user tasks.

You can use this feature for smooth transition between project versions without the need for process instance migration.

Invocation of the latest version of a process

If you need to use the latest version of the project’s process, you can use the latest keyword to interact with several operations in services. This approach is supported only when the process identifier remains the same in all versions.

The following example explains the feature.

The initial deployment unit is org.jbpm:HR:1.0. It contains the first version of a hiring process.

After several weeks, you develop a new version and deploy it to the execution server as org.jbpm:HR.2.0. It includes version 2 of the hiring process.

If you want to call the process and ensure that you use the latest version, you can use the following deployment ID:

org.jbpm.HR:latest

If you use this deployment ID, the process engine finds the latest available version of the project. It uses the following identifiers:

groupId: org.jbpm
artifactId: HR

The version numbers are compared by Maven rules to find the latest version.

The following code example shows deployment of multiple versions and interacting with the latest version:

Deploying multiple versions of a process and interacting with the latest version

KModuleDeploymentUnit deploymentUnitV1 = new KModuleDeploymentUnit("org.jbpm", "HR", "1.0");
deploymentService.deploy(deploymentUnitV1);

long processInstanceId = processService.startProcess("org.jbpm:HR:LATEST", "customtask");
ProcessInstanceDesc piDesc = runtimeDataService.getProcessInstanceById(processInstanceId);

// We have started a process with the project version 1
assertEquals(deploymentUnitV1.getIdentifier(), piDesc.getDeploymentId());

// Next we deploy version 2
KModuleDeploymentUnit deploymentUnitV2 = new KModuleDeploymentUnit("org.jbpm", "HR", "2.0");
deploymentService.deploy(deploymentUnitV2);

processInstanceId = processService.startProcess("org.jbpm:HR:LATEST", "customtask");
piDesc = runtimeDataService.getProcessInstanceById(processInstanceId);

// This time we have started a process with the project version 2
assertEquals(deploymentUnitV2.getIdentifier(), piDesc.getDeploymentId());

Note

This feature is also available in the KIE Server REST API. When sending a request with a deployment ID, you can use LATEST as the version identifier.

Additional resources

Interacting with Red Hat Process Automation Manager using KIE APIs

66.3.12. Deployment synchronization

Process engine services include a deployment synchronizer that stores available deployments into a database, including the deployment descriptor for every deployment.

The synchronizer also monitors this table to keep it in sync with other installations that might be using the same data source. This functionality is especially important when running in a cluster or when Business Central and a custom application must operate on the same artifacts.

By default, when running core services, you must configure synchronization. For EJB and CDI extensions, synchronization is enabled automatically.

The following code sample configures synchronization:

Configuring synchronization

TransactionalCommandService commandService = new TransactionalCommandService(emf);

DeploymentStore store = new DeploymentStore();
store.setCommandService(commandService);

DeploymentSynchronizer sync = new DeploymentSynchronizer();
sync.setDeploymentService(deploymentService);
sync.setDeploymentStore(store);

DeploymentSyncInvoker invoker = new DeploymentSyncInvoker(sync, 2L, 3L, TimeUnit.SECONDS);
invoker.start();
....
invoker.stop();

With this configuration, deployments are synchronized every three seconds with an initial delay of two seconds.

66.4. Threads in the process engine

We can refer to two types of multi-threading: logical and technical. Technical multi-threading involves multiple threads or processes that are started, for example, by a Java or C program. Logical multi-threading happens in a BPM process, for example, after the process reaches a parallel gateway. In execution logic, the original process splits into two processes that run in a parallel fashion.

Process engine code implements logical multi-threading using one technical thread.

The reason for this design choice is that multiple (technical) threads must be able to communicate state information to each other if they are working on the same process. This requirement brings a number of complications. The extra logic required for safe communication between threads, as well as the extra overhead required to avoid race conditions and deadlocks, can negate any performance benefit of using such threads.

In general, the process engine executes actions in series. For example, when the process engine encounters a script task in a process, it executes the script synchronously and waits for it to complete before continuing execution. In the same way, if a process encounters a parallel gateway, the process engine sequentially triggers each of the outgoing branches, one after the other.

This is possible because execution is almost always instantaneous, meaning that it is extremely fast and produces almost no overhead. As a result, sequential execution does not create any effects that a user can notice.

Any code in a process that you supply is also executed synchronously and the process engine waits for it to finish before continuing the process. For example, if you use a Thread.sleep(…) as part of a custom script, the process engine thread is blocked during the sleep period.

When a process reaches a service task, the process engine also invokes the handler for the task synchronously and waits for the completeWorkItem(…) method to return before continuing execution. If your service handler is not instantaneous, implement the asynchronous execution independently in your code.

For example, your service task might invoke an external service. The delay in invoking this service remotely and waiting for the results might be significant. Therefore, invoke this service asynchronously. Your handler must only invoke the service and then return from the method, then notify the process engine later when the results are available. In the meantime, the process engine can continue execution of the process.

Human tasks are a typical example of a service that needs to be invoked asynchronously. A human task requires a human actor to respond to a request, and the process engine must not wait for this response.

When a human task node is triggered, the human task handler only creates a new task on the task list of the assigned actor. The process engine is then able to continue execution on the rest of the process, if necessary. The handler notifies the process engine asynchronously when the user has completed the task.

66.5. Event Listeners in the process engine

You can develop a class that implements the ProcessEventListener interface. This class can listen to process-related events, such as starting or completing a process or entering and leaving a node.

The process engine passes an event object to this class. The object provides access to related information, like the process instance and node instance linked to the event.

The following list shows the different methods of the ProcessEventListener interface:

Methods of the ProcessEventListener interface

public interface ProcessEventListener {

  void beforeProcessStarted( ProcessStartedEvent event );
  void afterProcessStarted( ProcessStartedEvent event );
  void beforeProcessCompleted( ProcessCompletedEvent event );
  void afterProcessCompleted( ProcessCompletedEvent event );
  void beforeNodeTriggered( ProcessNodeTriggeredEvent event );
  void afterNodeTriggered( ProcessNodeTriggeredEvent event );
  void beforeNodeLeft( ProcessNodeLeftEvent event );
  void afterNodeLeft( ProcessNodeLeftEvent event );
  void beforeVariableChanged(ProcessVariableChangedEvent event);
  void afterVariableChanged(ProcessVariableChangedEvent event);

}

The before and after event calls typically act like a stack. If event A directly causes event B, the following sequence of calls happens:

Before A
Before B
After B
After A

For example, if leaving node X triggers node Y, all event calls related to triggering node Y occur between the beforeNodeLeft and afterNodeLeft calls for node X.

In the same way, if starting a process directly causes some nodes to start, all nodeTriggered and nodeLeft event calls occur between the beforeProcessStarted and afterProcessStarted calls.

This approach reflects cause and effect relationships between events. However, the timing and order of after event calls are not always intuitive. For example, an afterProcessStarted call can happen after the afterNodeLeft calls for some nodes in the process.

In general, to be notified when a particular event occurs, use the before call for the event. Use an after call only if you want to make sure that all processing related to this event has ended, for example, when you want to be notified when all steps associated with starting a particular process instance have been completed.

Depending on the type of node, some nodes might only generate nodeLeft calls and others might only generate nodeTriggered calls. For example, catch intermediate event nodes do not generate nodeTriggered calls, because they are not triggered by another process node. Similarly, throw intermediate event nodes do not generate nodeLeft calls, as these nodes do not have an outgoing connection to another node.

The KieSession class implements the RuleRuntimeEventManager interface that provides methods for registering, removing, and listing event listeners, as shown in the following list.

Methods of the RuleRuntimeEventManager interface

    void addEventListener(AgendaEventListener listener);
    void addEventListener(RuleRuntimeEventListener listener);
    void removeEventListener(AgendaEventListener listener);
    void removeEventListener(RuleRuntimeEventListener listener);
    Collection<AgendaEventListener>	getAgendaEventListeners();
    Collection<RuleRuntimeEventListener> getRuleRintimeEventListeners();

However, in a typical case, do not use these methods.

If you are using the RuntimeManager interface, you can use the RuntimeEnvironment class to register event listeners.

If you are using the Services API, you can add fully qualified class names of event listeners to the META-INF/services/org.jbpm.services.task.deadlines.NotificationListener file in your project. The Services API also registers some default listeners, including org.jbpm.services.task.deadlines.notifications.impl.email.EmailNotificationListener, which can send email notifications for events.

To exclude a default listener, you can add the fully qualified name of the listener to the org.kie.jbpm.notification_listeners.exclude JVM system property.

66.5.1. `KieRuntimeLogger` event listener

The KieServices package contains the KieRuntimeLogger event listener that you can add to your KIE session. You can use this listener to create an audit log. This log contains all the different events that occurred at runtime.

Note

These loggers are intended for debugging purposes. They might be too detailed for business-level process analysis.

The listener implements the following logger types:

Console logger: This logger writes out all the events to the console. The fully qualified class name for this logger is org.drools.core.audit.WorkingMemoryConsoleLogger.
File logger: This logger writes out all the events to a file using an XML representation. You can use the log file in an IDE to generate a tree-based visualization of the events that occurred during execution. The fully qualified class name for this logger is org.drools.core.audit.WorkingMemoryFileLogger.
The file logger writes the events to disk only when closing the logger or when the number of events in the logger reaches a predefined level. Therefore, it is not suitable for debugging processes at runtime.
Threaded file logger: This logger writes the events to a file after a specified time interval. You can use this logger to visualize the progress in real time while debugging processes. The fully qualified class name for this logger is org.drools.core.audit.ThreadedWorkingMemoryFileLogger.

When creating a logger, you must pass the KIE session as an argument. The file loggers also require the name of the log file to be created. The threaded file logger requires the interval in milliseconds after which the events are saved.

Always close the logger at the end of your application.

The following example shows the use of the file logger.

Using the file logger

  import org.kie.api.KieServices;
  import org.kie.api.logger.KieRuntimeLogger;
  ...
  KieRuntimeLogger logger = KieServices.Factory.get().getLoggers().newFileLogger(ksession, "test");
  // add invocations to the process engine here,
  // e.g. ksession.startProcess(processId);
  ...
  logger.close();

The log file that is created by the file-based loggers contains an XML-based overview of all the events that occurred during the runtime of the process.

66.6. Process engine configuration

You can use several control parameters available to alter the process engine default behavior to suit the requirements of your environment.

Set these parameters as JVM system properties, usually with the -D option when starting a program such as an application server.

Table 66.1. Control parameters
Name	Possible values	Default value	Description
`jbpm.ut.jndi.lookup`	String		Alternative JNDI name to be used when there is no access to the default name (`java:comp/UserTransaction`). NOTE: The name must be valid for the given runtime environment. Do not use this variable if there is no access to the default user transaction JNDI name.
`jbpm.enable.multi.con`	`true`\|`false`	`false`	Enable multiple incoming and outgoing sequence flows support for activities
`jbpm.business.calendar.properties`	String	/`jbpm.business.calendar.properties`	Alternative class path location of the business calendar configuration file
`jbpm.overdue.timer.delay`	Long	2000	Specifies the delay for overdue timers to allow proper initialization, in milliseconds
`jbpm.process.name.comparator`	String		Alternative comparator class to enable starting a process by name, by default the `NumberVersionComparator` comparator is used
`jbpm.loop.level.disabled`	`true`\|`false`	`true`	Enable or disable loop iteration tracking for advanced loop support when using XOR gateways
`org.kie.mail.session`	String	`mail`/`jbpmMailSession`	Alternative JNDI name for the mail session used by Task Deadlines
`jbpm.usergroup.callback.properties`	String	/`jbpm.usergroup.callback.properties`	Alternative class path location for a user group callback implementation (LDAP, DB)
`jbpm.user.group.mapping`	String	`${jboss.server.config.dir}/roles.properties`	Alternative location of the `roles.properties` file for `JBossUserGroupCallbackImpl`
`jbpm.user.info.properties`	String	/`jbpm.user.info.properties`	Alternative class path location of the user info configuration (used by `LDAPUserInfoImpl`)
`org.jbpm.ht.user.separator`	String	`,`	Alternative separator of actors and groups for user tasks
`org.quartz.properties`	String		Location of the Quartz configuration file to activate the Quartz-based timer service
`jbpm.data.dir`	String	`${jboss.server.data.dir}` if available, otherwise `${java.io.tmpdir}`	Location to store data files produced by the process engine
`org.kie.executor.pool.size`	Integer	`1`	Thread pool size for the process engine executor
`org.kie.executor.retry.count`	Integer	3	Number of retries attempted by the process engine executor in case of an error
`org.kie.executor.interval`	Integer	0	Frequency used to check for pending jobs by the process engine executor, in seconds. If the value is `0`, the check is run once, during the startup of the executor.
`org.kie.executor.disabled`	`true`\|`false`	`true`	Disable the process engine executor
`org.kie.store.services.class`	String	`org.drools.persistence.jpa.KnowledgeStoreServiceImpl`	Fully qualified name of the class that implements `KieStoreServices` that is responsible for bootstrapping `KieSession` instances
`org.kie.jbpm.notification_listeners.exclude`	String		Fully qualified names of event listeners that must be excluded even if they would otherwise be used. Separate multiple names with commas. For example, you can add `org.jbpm.services.task.deadlines.notifications.impl.email.EmailNotificationListener` to exclude the default email notification listener.
`org.kie.jbpm.notification_listeners.include`	String		Fully qualified names of event listeners that must be included. Separate multiple names with commas. If you set this property, only the listeners in this property are included and all other listeners are excluded.

Chapter 66. Core engine API for the process engine

66.1. KIE base and KIE session

66.1.1. KIE base

66.1.2. KIE session

66.1.3. ProcessRuntime interface

66.1.4. Correlation Keys

66.2. Runtime manager

66.2.1. Runtime manager strategies

66.2.2. Typical usage scenario for the runtime manager

66.2.3. Runtime environment configuration object

66.2.4. Runtime environment builder

66.2.5. Registration of handlers and listeners for runtime engines

66.2.5.1. Registering work item handlers using a file

66.2.5.2. Registration of handlers and listeners in a CDI environment

66.3. Services in the process engine

66.3.1. Modules for process engine services

66.3.2. Deployment service

66.3.3. Definition service

66.3.4. Process service

66.3.5. Runtime Data Service

66.3.6. User Task Service

66.3.7. Quartz-based timer service

66.3.8. Query service

66.3.8.1. Key classes of the query service

66.3.8.2. Using the query service in a typical scenario

66.3.9. Advanced query service

66.3.10. Process instance migration service

Known limitations of process instance migration

66.3.11. Deployments and different process versions

Activation and Deactivation of deployments

Invocation of the latest version of a process

66.3.12. Deployment synchronization

66.4. Threads in the process engine

66.5. Event Listeners in the process engine

66.5.1. KieRuntimeLogger event listener

66.6. Process engine configuration

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66.5.1. `KieRuntimeLogger` event listener