HumanTask Event Listeners - WSO2 BPS

HumanTask engine comes with a humantask event generator. These task events are generated when a task goes trough a state transition. An event contains details about tasks and its state transition. So by writing a custom event listener to these events, a developer can easily enhance the HumanTask engine's functionalities.

What developer can do with a task event listener.

• Can do custom java code/ web service invocations.
• Can retrieve task information. 
• Developer free to implement their own logic depending on their requirement.

Sample Event Listener.

EventListener class should implement HumanTaskEventListener class and onEvent method. See following sample code.

	package org.wso2.carbon.humantask.sample;
	import org.wso2.carbon.humantask.core.api.event.HumanTaskEventListener;
	import org.wso2.carbon.humantask.core.api.event.TaskEventInfo;
	import org.wso2.carbon.humantask.core.dao.TaskType;
	public class SimpleEventListener implements HumanTaskEventListener {
	@Override
	public void onEvent(TaskEventInfo taskEventInfo) {
	System.out.println("[ Task ID : " + taskEventInfo.getTaskInfo().getId() + " ] [ Event : " + taskEventInfo.getEventType() + " ] at " + taskEventInfo.getTaskInfo().getModifiedDate());
	if (taskEventInfo.getTaskInfo().getType() == TaskType.TASK) {
	System.out.println("\tTask Name :" + taskEventInfo.getTaskInfo().getName());
	System.out.println("\tTask Subject :" + taskEventInfo.getTaskInfo().getSubject());
	System.out.println("\tTask Description :" + taskEventInfo.getTaskInfo().getDescription());
	System.out.println("\tTask Owner : " + taskEventInfo.getTaskInfo().getOwner());
	} else if (taskEventInfo.getTaskInfo().getType() == TaskType.NOTIFICATION) {
	System.out.println("\tNotification Name :" + taskEventInfo.getTaskInfo().getName());
	System.out.println("\tNotification Subject :" + taskEventInfo.getTaskInfo().getSubject());
	System.out.println("\tNotification Description :" + taskEventInfo.getTaskInfo().getDescription());
	}
	}
	}

view raw SimpleEventListener.java hosted with ❤ by GitHub

How to deploy a custom listener to WSO2 BPS

1. Build a jar file of including your listener.
2. Copy it into /repository/components/lib. Where is the root directory of BPS server.
3. Uncomment TaskEventListeners in HumanTask configuration file (/repository/conf/humantask.xml) and give your Event Listener class name for ClassName.
eg:

	<TaskEventListeners>
	<ClassName>org.wso2.carbon.humantask.sample.SampleEventListener</ClassName>
	</TaskEventListeners>

view raw humantask.xml hosted with ❤ by GitHub

Note: you can have multiple listener classes.

4. Start BPS.
5. Execute a task.