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Chapter 109. 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.
109.1. 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>
109.2. URI format
saga:action
109.3. Configuring Options
Camel components are configured on two levels:
- Component level
- Endpoint level
109.3.1. Component Level Options
The component level is the highest level. The configurations you define at this level are inherited by all the endpoints. For example, a component can have security settings, credentials for authentication, urls for network connection, and so on.
Since components typically have pre-configured defaults for the most common cases, you may need to only configure a few component options, or maybe none at all.
You can configure components with Component DSL in a configuration file (application.properties|yaml), or directly with Java code.
109.3.2. Endpoint Level Options
At the Endpoint level you have many options, which you can use to configure what you want the endpoint to do. The options are categorized according to whether the endpoint is used as a consumer (from) or as a producer (to) or used for both.
You can configure endpoints directly in the endpoint URI as path and query parameters. You can also use Endpoint DSL and DataFormat DSL as type safe ways of configuring endpoints and data formats in Java.
When configuring options, use Property Placeholders for urls, port numbers, sensitive information, and other settings.
Placeholders allows you to externalize the configuration from your code, giving you more flexible and reusable code.
109.4. 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 |
109.5. Endpoint Options
The Saga endpoint is configured using URI syntax:
saga:action
with the following path and query parameters:
109.5.1. Path Parameters (1 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
| action (producer) | Required Action to execute (complete or compensate). Enum values:
| SagaEndpointAction |
109.5.2. 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 |
109.6. 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.
109.7. 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 |
