Examples

Working example

We provide demonstrating the usage of the library, depending on the context.

Standalone usage

The example demonstrates the usage of the library accessing a process engine via REST from an arbitrary SpringBoot application. The client executes the following steps:

Timing overview of the example

Initial offset	Repeat	Invoked method
8.0 sec	-	Get deployed processes
10.0 sec	5 sec	Start process
12.5 sec	5 sec	Send signal
13.0 sec	5 sec	Correlate message

How does it work

The application uses the library by adding it to the classpath via Apache Maven dependency. That is:

<dependency>
  <groupId>org.camunda.community.rest</groupId>
  <artifactId>camunda-platform-7-rest-client-spring-boot-starter</artifactId>
  <version>${project.version}</version>
</dependency>

In order to activate the library, the @EnableCamundaRestClient has been put on the configuration class of the application. The interesting part is now the ProcessClient component. This Spring Component has several methods marked with @Scheduled annotation to demonstrate the time-based execution of desired functionality. To do so, the component has two injected resources, both marked with the @Qualifier("remote") annotation. This annotation indicates that the remote version of the Camunda API services are used.

In order to configure the library, a block of properties e.g. in application.yml is required. The values specify the location of the remote process engine:

feign:
  client:
    config:
      default:
        url: "http://localhost:8083/engine-rest/"

To run this example, you will need the server part from the next example. To activate the server part only, please run from command line:

mvn clean install
mvn -f examples/example -Prun
mvn -f examples/example-provided -Prun-server-only

Usage inside a process application

The example demonstrates the usage of the library for accessing a process engine via REST from a Camunda Platform 7 process application. The key difference to the previous example is that the required Camunda classes are already present on the classpath and an engine is initialized and is running.

Imagine the process engine has the following process deployed:

The client (running technically in the same JVM, but accessing the engine via REST) again executes the following steps:

Timing overview of the example

Initial offset	Repeat	Invoked method
8.0 sec	-	Get deployed processes
10.0 sec	5 sec	Start process
12.5 sec	5 sec	Send signal
13.0 sec	5 sec	Correlate message

How does it work

The application uses the library by adding it to the classpath via Apache Maven dependency. That is:

<dependency>
  <groupId>org.camunda.community.rest</groupId>
  <artifactId>camunda-platform-7-rest-client-spring-boot-starter-provided</artifactId>
  <version>${project.version}</version>
</dependency>

NOTE: Please note that we use a different starter. The suffix provided in the artifact name indicates that the engine is already a part of the application and doesn't need to be put on classpath.

In order to activate the library, the @EnableCamundaRestClient has been put on the configuration class of the application. The interesting part is now the ProcessClient component. This Spring Component has several methods marked with @Scheduled annotation to demonstrate the time-based execution of desired functionality. To do so, the component has two injected resources, both marked with the @Qualifier("remote") annotation. This annotation indicates that the remote version of the Camunda API services are used.

In order to configure the library, a block of properties e.g. in application.yml is required:

feign:
  client:
    config:
      default:
        url: "http://localhost:8083/engine-rest/"

Usage of feign clients

The example demonstrates the usage of the library for accessing the REST from a Camunda Platform 7 process application using the generated feign clients. The difference to the previous examples is that no Camunda dependency is required on the classpath, as the feign clients are used directly.

How does it work

The application uses the library by adding it to the classpath via Apache Maven dependency. That is:

<dependency>
  <groupId>org.camunda.community.rest</groupId>
  <artifactId>camunda-platform-7-rest-client-spring-boot-openapi</artifactId>
  <version>${project.version}</version>
</dependency>

In order to activate the library, the @EnableCamundaFeignClients has to be put on the configuration class of the application. The interesting part is now the ProcessClient component. This Spring Component has several methods marked with @Scheduled annotation to demonstrate the time-based execution of desired functionality. To do so, the component has injected the needed feign clients as resources.

In order to configure the library, the same block of properties e.g. in application.yml as before is required:

feign:
  client:
    config:
      ...