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Chapter 3. Managing services
3.1. Configuring OpenAPI services
The OpenAPI Specification (OAS) defines a standard, programming language-agnostic interface for HTTP APIs. You can understand a service’s capabilities without access to the source code, additional documentation, or network traffic inspection. When you define a service by using the OpenAPI, you can understand and interact with it using minimal implementation logic. Just as interface descriptions simplify lower-level programming, the OpenAPI Specification eliminates guesswork in calling a service.
3.1.1. OpenAPI function definition
OpenShift Serverless Logic allows the workflows to interact with remote services using an OpenAPI specfication reference in a function.
Example OpenAPI function definition
					The operation attribute is a string composed of the following parameters:
				
- 
							URI: The engine uses this to locate the specification file.
- Operation identifier: You can find this identifier in the OpenAPI specification file.
OpenShift Serverless Logic supports the following URI schemes:
- file: Use this for files located in the file system.
- 
							httporhttps: Use these for remotely located files.
Ensure the OpenAPI specification files are available during build time. OpenShift Serverless Logic uses an internal code generation feature to send requests at runtime. After you build the application image, OpenShift Serverless Logic will not have access to these files.
If the OpenAPI service you want to add to the workflow does not have a specification file, you can either create one or update the service to generate and expose the file.
3.1.2. Sending REST requests based on the OpenAPI specification
To send REST requests that are based on the OpenAPI specification files, you must perform the following procedures:
- Define the function references
- Access the defined functions in the workflow states
Prerequisites
- You have OpenShift Serverless Logic Operator installed on your cluster.
- You have access to a OpenShift Serverless Logic project with the appropriate roles and permissions to create applications and other workloads in OpenShift Container Platform.
- You have access to the OpenAPI specification files.
Procedure
- To define the OpenAPI functions: - Identify and access the OpenAPI specification files for the services you intend to invoke.
- Copy the OpenAPI specification files into your workflow service directory, such as - <project_application_dir>/specs.- The following example shows the OpenAPI specification for the multiplication REST service: - Example multiplication REST service OpenAPI specification - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- To define functions in the workflow, use the - operationIdfrom the OpenAPI specification to reference the desired operations in your function definitions.- Example function definitions in the temperature conversion application - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- 
									Ensure that your function definitions reference the correct paths to the OpenAPI files stored in the <project_application_dir>/specsdirectory.
 
- To access the defined functions in the workflow states: - Define workflow actions to call the function definitions you added. Ensure each action references a function defined earlier.
- Use the - functionRefattribute to refer to the specific function by its name. Map the arguments in the- functionRefusing the parameters defined in the OpenAPI specification.- The following example shows about mapping parameters in the request path instead of request body, you can refer to the following PetStore API example: - Example for mapping function arguments in workflow - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- 
									Check the Operation Objectsection of the OpenAPI specification to understand how to structure parameters in the request.
- 
									Use jqexpressions to extract data from the payload and map it to the required parameters. Ensure the engine maps parameter names according to the OpenAPI specification.
- For operations requiring parameters in the request path instead of the body, refer to the parameter definitions in the OpenAPI specification. - For more information about mapping parameters in the request path instead of request body, you can refer to the following PetStore API example: - Example for mapping path parameters - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Following is an example invocation of a function, in which only one parameter named - petIdis added in the request path:- Example of calling the PetStore function - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
 
3.1.3. Configuring the endpoint URL of OpenAPI services
After accessing the function definitions in workflow states, you can configure the endpoint URL of OpenAPI services.
Prerequisites
- You have access to a OpenShift Serverless Logic project with the appropriate roles and permissions to create applications and other workloads in OpenShift Container Platform.
- You have created your OpenShift Serverless Logic project.
- You have access to the OpenAPI specification files.
- You have defined the function definitions in the workflow.
- You have the access to the defined functions in the workflow states.
Procedure
- 
							Locate the OpenAPI specification file you want to configure. For example, substraction.yaml.
- 
							Convert the file name into a valid configuration key by replacing special characters, such as ., with underscores and converting letters to lowercase. For example, changesubstraction.yamltosubstraction_yaml.
- To define the configuration key, use the converted file name as the REST client configuration key. Set this key as an environment variable, as shown in the following example: - quarkus.rest-client.subtraction_yaml.url=http://myserver.com - quarkus.rest-client.subtraction_yaml.url=http://myserver.com- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- To prevent hardcoding URLs in the - application.propertiesfile, use environment variable substitution, as shown in the following example:- quarkus.rest-client.subtraction_yaml.url=${SUBTRACTION_URL:http://myserver.com}- quarkus.rest-client.subtraction_yaml.url=${SUBTRACTION_URL:http://myserver.com}- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - In this example: - 
									Configuration Key: quarkus.rest-client.subtraction_yaml.url
- Environment variable: SUBTRACTION_URL
- 
									Fallback URL: http://myserver.com
 
- 
									Configuration Key: 
- 
							Ensure that the (SUBTRACTION_URL)environment variable is set in your system or deployment environment. If the variable is not found, the application uses the fallback URL(http://myserver.com).
- Add the configuration key and URL substitution to the - application.propertiesfile:- quarkus.rest-client.subtraction_yaml.url=${SUBTRACTION_URL:http://myserver.com}- quarkus.rest-client.subtraction_yaml.url=${SUBTRACTION_URL:http://myserver.com}- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Deploy or restart your application to apply the new configuration settings.
3.2. Configuring OpenAPI services endpoints
				OpenShift Serverless Logic uses the kogito.sw.operationIdStrategy property to generate the REST client for invoking services defined in OpenAPI documents. This property determines how the configuration key is derived for the REST client configuration.
			
				The kogito.sw.operationIdStrategy property supports the following values: FILE_NAME, FULL_URI, FUNCTION_NAME, and SPEC_TITLE.
			
- FILE_NAME
- OpenShift Serverless Logic uses the OpenAPI document file name to create the configuration key. The key is based on the file name, where special characters are replaced with underscores. - Example configuration: - quarkus.rest-client.stock_portfolio_svc_yaml.url=http://localhost:8282/ - quarkus.rest-client.stock_portfolio_svc_yaml.url=http://localhost:8282/- 1 - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - 1
- The OpenAPI file path is<project_application_dir>/specs/stock-portfolio-svc.yaml. The generated key that configures the URL for the REST client isstock_portfolio_svc_yaml.
 
- FULL_URI
- OpenShift Serverless Logic uses the complete URI path of the OpenAPI document as the configuration key. The full URI is sanitized to form the key. - Example for Serverless Workflow - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Example configuration: - quarkus.rest-client.apicatalog_apis_123_document.url=http://localhost:8282/ - quarkus.rest-client.apicatalog_apis_123_document.url=http://localhost:8282/- 1 - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - 1
- The URI path ishttps://my.remote.host/apicatalog/apis/123/document. The generated key that configures the URL for the REST client isapicatalog_apis_123_document.
 
- FUNCTION_NAME
- OpenShift Serverless Logic combines the workflow ID and the function name referencing the OpenAPI document to generate the configuration key. - Example for Serverless Workflow - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Example configuration: - quarkus.rest-client.myworkflow_myfunction.url=http://localhost:8282/ - quarkus.rest-client.myworkflow_myfunction.url=http://localhost:8282/- 1 - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - 1
- The workflow ID ismyworkflow. The function name ismyfunction. The generated key that configures the URL for the REST client ismyworkflow_myfunction.
 
- SPEC_TITLE
- OpenShift Serverless Logic uses the - info.titlevalue from the OpenAPI document to create the configuration key. The title is sanitized to form the key.- Example for OpenAPI document - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Example configuration: - quarkus.rest-client.stock-service_API.url=http://localhost:8282/ - quarkus.rest-client.stock-service_API.url=http://localhost:8282/- 1 - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - 1
- The OpenAPI document title isstock-service API. The generated key that configures the URL for the REST client isstock-service_API.
 
3.2.1. Using URI alias
					As an alternative to the kogito.sw.operationIdStrategy property, you can assign an alias to a URI by using the workflow-uri-definitions custom extension. This alias simplifies the configuration process and can be used as a configuration key in REST client settings and function definitions.
				
					The workflow-uri-definitions extension allows you to map a URI to an alias, which you can reference throughout the workflow and in your configuration files. This approach provides a centralized way to manage URIs and their configurations.
				
Prerequisites
- You have access to a OpenShift Serverless Logic project with the appropriate roles and permissions to create applications and other workloads in OpenShift Container Platform.
- You have access to the OpenAPI specification files.
Procedure
- Add the - workflow-uri-definitionsextension to your workflow. Within this extension, create aliases for your URIs.- Example workflow - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- 1
- Set the extension ID toworkflow-uri-definitions.
- 2
- Set the alias definition by mapping theremoteCatalogalias to a URI, for example,https://my.remote.host/apicatalog/apis/123/documentURI.
- 3
- Set the function operations by using theremoteCatalogalias with the operation identifiers, for example,operation1andoperation2operation identifiers.- In the - application.propertiesfile, configure the REST client by using the alias defined in the workflow.- Example property - quarkus.rest-client.remoteCatalog.url=http://localhost:8282/ - quarkus.rest-client.remoteCatalog.url=http://localhost:8282/- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - In the previous example, the configuration key is set to - quarkus.rest-client.remoteCatalog.url, and the URL is set to- http://localhost:8282/, which the REST clients use by referring to the- remoteCatalogalias.
- In your workflow, use the alias when defining functions that operate on the URI. - Example Workflow (continued): - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
 
3.3. Troubleshooting services
Efficient troubleshooting of the HTTP-based function invocations, such as those using OpenAPI functions, is crucial for maintaining workflow orchestrations.
To diagnose issues, you can trace HTTP requests and responses.
3.3.1. Tracing HTTP requests and responses
OpenShift Serverless Logic uses the Apache HTTP client to the trace HTTP requests and responses.
Prerequisites
- You have access to an OpenShift Serverless Logic project with the appropriate roles and permissions to create applications and other workloads in OpenShift Container Platform.
- You have access to the OpenAPI specification files.
- You have access to the workflow definition and instance IDs for correlating HTTP requests and responses.
- You have access to the log configuration of the application where the HTTP service invocations are occurring
Procedure
- To trace HTTP requests and responses, OpenShift Serverless Logic uses the Apache HTTP client by setting the following property: - Turning HTTP tracing on - # Turning HTTP tracing on quarkus.log.category."org.apache.http".level=DEBUG- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Add the following configuration to your application’s - application.propertiesfile to turn on debugging for the Apache HTTP Client:- quarkus.log.category."org.apache.http".level=DEBUG - quarkus.log.category."org.apache.http".level=DEBUG- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Restart your application to propagate the log configuration changes.
- After restarting, check the logs for HTTP request traces. - Example logs of a traced HTTP request - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Check the logs for HTTP response traces following the request logs. - Example logs of a traced HTTP response - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow