This repository contains a library that enables your JavaEE application as a Client for the Camunda-Platform-8 process engine.
You can reuse your existing JavaEE code and use @ApplicationScoped
beans in a
job handler as the implementation for BPMN Service tasks and other elements.
The library contains a single startup bean to activate the workers. (ZeebeEjbProcessApplication)
All application scoped beans that are annotated with
@JobWorker(type = "mytype")
are registered as workers on the Zeebe process
engine.
The Library uses the Zeebe java client configuration properties.
It reads a file named zeebeClient.properties
from the class-path.
Connection properties for Camunda 8 SaaS Cloud cluster:
zeebe.client.cloud.clusterId=xxx
zeebe.client.cloud.clientId=xxx
zeebe.client.cloud.secret=xxx
zeebe.client.cloud.region=bru-2
Connection properties for a local installation with Docker compose:
zeebe.client.gateway.address=localhost:26500
zeebe.client.security.plaintext=true
Other client connection properties are mentioned in this class: io.camunda.zeebe.client.ClientProperties
To reuse existing CDI DelegateExpressions
in Camunda 8, you can add this
library to your project:
<dependency>
<groupId>org.camunda.community.client</groupId>
<artifactId>camunda-7-cdi-adapter</artifactId>
<version>0.0.2-SNAPSHOT</version>
</dependency>
It will use a task type camunda-7-adapter
and look for configurations like
<zeebe:header key="delegateExpression" value="${customerCreditDelegate}" />
.
These elements are created during the migration of the BPMN Diagram from Camunda
7 to Camunda 8 with the
Diagram Converter.
The full XML element of a service task using the Camunda 7 CDI adapter:
<bpmn:serviceTask id="Activity_1vwtc60" name="Deduct customer credit">
<bpmn:extensionElements>
<zeebe:taskDefinition type="camunda-7-adapter" />
<zeebe:taskHeaders>
<zeebe:header key="delegateExpression" value="${customerCreditDelegate}" />
</zeebe:taskHeaders>
</bpmn:extensionElements>
<bpmn:incoming>Flow_04h7vab</bpmn:incoming>
<bpmn:outgoing>Flow_0tr3idd</bpmn:outgoing>
</bpmn:serviceTask>
This repository also contains an example that shows how to reuse existing EJBs in your Zeebe client on a Java-EE Server.
The Zeebe EJB client library registers all methods and classes that are
annotated with @JobWorker(taskType="myType")
.
The Job workers require an @ApplicationScoped
annotation for this. See
CustomerCreditWorker.java.
The Service implementation itself gets injected to the worker. They are
annotated with @Stateless
. See
CustomerService.java
To run the examples, you can deploy it to a running Wildfly server with
mvn clean wildfly:deploy
. During deployment all workers are registered in the
Zeebe process engine and get activated.
You can find the full example here.
The example contains a REST Api to start process instances. Check the content of
the package com.camunda.consulting.zeebe_ejb.rest
.
To start process instances, use a REST client like curl:
curl for cmd.exe
curl --location --request POST "http://localhost:8080/zeebe-ejb-example-worker-interface/payment/command/start/" ^
--header "Content-Type: application/json" ^
--data-raw "{\"customerId\": \"12\", \"orderTotal\": 39.99, \"creditCardNumber\": \"1234123412341234\", \"cvc\": \"789\", \"expiryDate\": \"07/24\"}"
Just replace the Camunda 7 engine dependency with the camunda-7-cdi-adapter dependency in the pom.xml.
And add the connection properties pointing to the Zeebe cluster to your project.