title: How to specify service task in BPMN 2.0 to execute custom java code in JBPM 5
body: <p>I'd like to add service test in JBPM-5 using BPMN-2.0 using only XML syntax. I want that service task to have an input and output parameters of some Java type.
  <br/>Lets say I created <strong>mypackage.MyCustomTaskWorkItemHandler</strong> for my service task and registered it in corresponding WorkItemManager like <strong>MyCustomTask</strong>.<br/>
  Now I'd like to describe a call of this service task in BPMN XML file.</p>
  
  <pre><code>&lt;serviceTask id="myCustomTask1" ... implementation=??? operationRef=???&gt;
      &lt;!-- incoming,outgoing,etc --&gt;
      &lt;ioSpecification&gt;
          ...
      &lt;/ioSpecification&gt;
  &lt;/serviceTask&gt;
  </code></pre>
  
  <p>Tag serviceTask is from <a href="http://www.omg.org/spec/BPMN/20100524/MODEL" rel="nofollow">http://www.omg.org/spec/BPMN/20100524/MODEL</a> namespace. How exacty should I specify input and output parameters for it?</p>