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Chapter 117. Saga
Only producer is supported
The Saga component provides a bridge to execute custom actions within a route using the Saga EIP.
The component should be used for advanced tasks, such as deciding to complete or compensate a Saga with completionMode set to MANUAL.
Refer to the Saga EIP documentation for help on using sagas in common scenarios.
117.1. Dependencies
When using saga with Red Hat build of Camel Spring Boot make sure to use the following Maven dependency to have support for auto configuration:
<dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-saga-starter</artifactId> </dependency>
<dependency>
<groupId>org.apache.camel.springboot</groupId>
<artifactId>camel-saga-starter</artifactId>
</dependency>117.2. URI format
saga:action
saga:action117.3. Configuring Options
Camel components are configured on two separate levels:
- component level
- endpoint level
117.3.1. Configuring Component Options
At the component level, you set general and shared configurations that are, then, inherited by the endpoints. It is the highest configuration level. For example, a component may have security settings, credentials for authentication, urls for network connection and so forth. Some components only have a few options, and others may have many. Because components typically have pre-configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.
You can configure components using:
- the Component DSL.
- in a configuration file (application.properties, *.yaml files, etc).
- directly in the Java code.
117.3.2. Configuring Endpoint Options
You usually spend more time setting up endpoints because they have many options. These options help you customize what you want the endpoint to do. The options are also categorized into whether the endpoint is used as a consumer (from), as a producer (to), or both.
Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java.
A good practice when configuring options is to use Property Placeholders.
Property placeholders provide a few benefits:
- They help prevent using hardcoded urls, port numbers, sensitive information, and other settings.
- They allow externalizing the configuration from the code.
- They help the code to become more flexible and reusable.
The following two sections list all the options, firstly for the component followed by the endpoint.
117.4. Component Options
The Saga component supports 2 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| lazyStartProducer (producer) | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean |
| autowiredEnabled (advanced) | Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. | true | boolean |
117.5. Endpoint Options
The Saga endpoint is configured using URI syntax:
saga:action
saga:actionwith the following path and query parameters:
117.5.1. Path Parameters (1 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
| action (producer) | Required Action to execute (complete or compensate). Enum values:
| SagaEndpointAction |
117.5.2. Query Parameters (1 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
| lazyStartProducer (producer) | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean |
117.6. Using camel-saga with Spring Boot and LRA coordinator
This example shows how to work with Apache Camel Saga using Spring Boot and Narayana LRA Coordinator to manage long running actions. See Saga example for more information.
117.7. Spring Boot Auto-Configuration
The component supports 3 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| camel.component.saga.autowired-enabled | Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. | true | Boolean |
| camel.component.saga.enabled | Whether to enable auto configuration of the saga component. This is enabled by default. | Boolean | |
| camel.component.saga.lazy-start-producer | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | Boolean |
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