11:31 a.m.
Melih Cetin [http://community.jboss.org/people/mscetin] created the discussion
"ReceiveTaskHandler handling multiple process intances with the same
message-id"
To view the discussion, visit: http://community.jboss.org/message/617949#617949
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BPMN2 JUnit test for BPMN2-ReceiveTask is implemented as
ksession.getWorkItemManager().registerWorkItemHandler("Receive Task",
receiveTaskHandler);
...
receiveTaskHandler.messageReceived("HelloMessage", "Hello john!");
I tried to use ReceiveTaskHandler class in a project to receive a notification from an
external system for a specific process-instance and resume the process upon receipt of the
message. I could not figure out how to specify the process-instance for which the received
message is applicable.
JUinit test works fine as there is only one process instance in the session during the
execution of this test. The source code for ReceiveTaskHandler is:
public class ReceiveTaskHandler implements WorkItemHandler {
// TODO: use correlation instead of message id
private Map<String, Long> waiting = new HashMap<String, Long>();
...
public void executeWorkItem(WorkItem workItem, WorkItemManager manager) {
String messageId = (String) workItem.getParameter("MessageId");
waiting.put(messageId, workItem.getId());
* // If waiting map previously contained a mapping for messageId, the old value is
replaced !!!*
}
public void messageReceived(String messageId, Object message) {
Long workItemId = waiting.get(messageId);
if (workItemId == null) {
return;
}
Map<String, Object> results = new HashMap<String, Object>();
results.put("Message", message);
ksession.getWorkItemManager().completeWorkItem(workItemId, results);
}
...
}
The comment of // TODO: use correlation instead of message id at the top of the source
file also gave the impression that the implementation is not complete. As an interim
solution, I decided to extend ReceiveTaskHandler class as follows:
public class ReceiveTaskHandler extends org.jbpm.bpmn2.handler.ReceiveTaskHandler {
private Map<String, Long> waiting = new HashMap<String, Long>();
private KnowledgeRuntime ksession;
public ReceiveTaskHandler(KnowledgeRuntime ksession) {
super(ksession);
this.ksession = ksession;
}
private String constructKey(long processInstanceId, String messageId) {
return processInstanceId + "|" + messageId;
}
@Override
public void executeWorkItem(WorkItem workItem, WorkItemManager manager) {
long processInstanceId = workItem.getProcessInstanceId();
String messageId = (String) workItem.getParameter("MessageId");
waiting.put(constructKey(processInstanceId, messageId), workItem.getId());
// If waiting map previously contained a mapping for messageId, the old value is
replaced !!!
}
@Override
public void messageReceived(String messageId, Object message) {
throw new UnsupportedOperationException(
"messageReceived(String messageId, Object message) method is not
supported. " +
"Instead use messageReceived(long, String, Object) method" );
}
public void messageReceived(long processInstanceId, String messageId, Object message)
{
Long workItemId = waiting.get(constructKey(processInstanceId, messageId));
if (workItemId == null) {
return;
}
Map<String, Object> results = new HashMap<String, Object>();
results.put("Message", message);
ksession.getWorkItemManager().completeWorkItem(workItemId, results);
}
}
I was wondering if "Receive Task" is the right task to use for waiting an
external notification. If yes, then can any core jBPM contributor review the extension
that I used locally and consider adding it to the next release of jBPM.
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