Spring configured embedded process engine and REST API
This example demonstrates how to setup a webapplication, which
- bundles the camunda-engine JAR library
- starts and configures a process engine in a Spring Applicaiton context
- bundles the camunda-engine-REST library
- exposes the process engine API via REST
NOTE: this project must be deployed on a vanilla Apache Tomcat server, NOT the prepackaged distribution which can be downloaded from camunda.org.
Why is this example interesting?
This example demonstrates how to perform a standalone embedded setup with a webapplication which bundles both the camunda engine and camunda engine REST jars.
Show me the important parts!
The process engine is configured in the Spring application context:
<bean id="processEngineConfiguration"
class="org.camunda.bpm.engine.spring.SpringProcessEngineConfiguration">
<property name="processEngineName" value="default" />
<property name="dataSource" ref="dataSource" />
<property name="transactionManager" ref="transactionManager" />
<property name="databaseSchemaUpdate" value="true" />
<property name="jobExecutorActivate" value="false" />
<property name="deploymentResources" value="classpath*:*.bpmn" />
</bean>
<bean id="processEngine" class="org.camunda.bpm.engine.spring.ProcessEngineFactoryBean">
<property name="processEngineConfiguration" ref="processEngineConfiguration" />
</bean>
<bean id="repositoryService" factory-bean="processEngine"
factory-method="getRepositoryService" />
<bean id="runtimeService" factory-bean="processEngine"
factory-method="getRuntimeService" />
<bean id="taskService" factory-bean="processEngine"
factory-method="getTaskService" />
<bean id="historyService" factory-bean="processEngine"
factory-method="getHistoryService" />
<bean id="managementService" factory-bean="processEngine"
factory-method="getManagementService" />
A custom JAX-RS Application class deploys the REST Endpoints:
public class RestProcessEngineDeployment extends Application {
@Override
public Set<Class<?>> getClasses() {
Set<Class<?>> classes = new HashSet<Class<?>>();
classes.add(ProcessEngineRestServiceImpl.class);
classes.add(JacksonConfigurator.class);
classes.add(JacksonJsonProvider.class);
classes.add(JsonMappingExceptionMapper.class);
classes.add(JsonParseExceptionMapper.class);
classes.add(ProcessEngineExceptionHandler.class);
classes.add(RestExceptionHandler.class);
return classes;
}
}
Implement the REST Process Engine Provider SPI (provides the process engine to the REST application):
public class RestProcessEngineProvider implements ProcessEngineProvider {
public ProcessEngine getDefaultProcessEngine() {
return ProcessEngines.getDefaultProcessEngine();
}
public ProcessEngine getProcessEngine(String name) {
return ProcessEngines.getProcessEngine(name);
}
public Set<String> getProcessEngineNames() {
return ProcessEngines.getProcessEngines().keySet();
}
}
Add a file named: src/main/resources/META-INF/services/org.camunda.bpm.engine.rest.spi.ProcessEngineProvider Which contains the name of the provider: org.camunda.bpm.example.loanapproval.rest.RestProcessEngineProvider
Reference all required libraries in pom.xml:
<dependency>
<groupId>org.camunda.bpm</groupId>
<artifactId>camunda-engine</artifactId>
<version>${camunda.version}</version>
</dependency>
<dependency>
<groupId>org.camunda.bpm</groupId>
<artifactId>camunda-engine-spring</artifactId>
<version>${camunda.version}</version>
</dependency>
<dependency>
<groupId>org.camunda.bpm</groupId>
<artifactId>camunda-engine-rest</artifactId>
<version>${camunda.version}</version>
<classifier>classes</classifier>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxrs</artifactId>
<version>3.0.2.Final</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
How to use it?
- Build it with maven
- Deploy it to a vanilla Apache Tomcat server, NOT the prepackaged distribution which can be downloaded from camunda.org!!
- Access the REST Endpoint: http://localhost:8080/camunda-quickstart-embedded-spring-rest-7.1.0-Final/engine/default/process-definition
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