1 Reply Latest reply on Aug 22, 2008 8:47 AM by Ronald van Kuijk

    Problem with timers

    Petia Wohed Newbie

      Thanks Roland, here I am starting a new topic.

      I have a problem with setting a timer on a Task Node.

      I have defined the following process

      <?xml version="1.0" encoding="UTF-8"?>
      <process-definition xmlns="urn:jbpm.org:jpdl-3.2" name="timer-test">
       <swimlane name="Initiator">
       <assignment actor-id="admin"></assignment>
       <start-state name="start-state1">
       <task name="start task" swimlane="Initiator"></task>
       <transition to="TaskA"></transition>
       <task-node name="TaskA">
       <task name="TaskA">
       <assignment actor-id="petia"></assignment>
       <timer duedate="10 seconds" transition="skipB"></timer>
       <transition to="TaskB" name="execute B"></transition>
       <transition to="end-state1" name="skipB"></transition>
       <task-node name="TaskB">
       <task name="TaskB">
       <assignment actor-id="petia"></assignment>
       <transition to="end-state1"></transition>
       <end-state name="end-state1"></end-state>

      The idea is that if the timer in Task Node TaskA expires the process will be ended (and the Task Node TaskB skipped).

      However, when running the process and the timer expires, the transition skipB is not executed (as specified in the code) and the process stalls at Task Node TaskA (which appears in the tasks list, but without an "End" button available for it).

      I am running jBPM 3.2.3. From the discussion on http://www.jboss.com/index.html?module=bb&op=viewtopic&t=140634&postdays=0&postorder=asc&start=10 I can see that there have been some problems with timers on State Nodes which apparently have been fixed in 3.2.4. Does this apply to my problem with timers on task nodes? Have anyone else experienced a similar problem?

      Note, the timer is important. Example of a business scenario: if a notification is not registered within a week, the process is ended otherwise it is continued. Therefore, the solution proposed by Alejandro (thanks Alejandro) suggesting that the timer is replaced by asynchronous continuation (see below), can not be applied in this case.

      JBSEAM-1575 depends on JBPM-1135 which is already resolved. That said, I have two suggestions.

      The first is to replace the timer with an asynchronous continuation, unless you need the delay (which I understand you do not). Just set the node's async attribute to true. It does not need to be a separate emtpy state, you can decorate any of your existing nodes with that attribute.

      The second is to implement a ThreadLocal based solution which prevents recursive calls once the loop node is reached. I came to it for preventing the stack overflow in the BPEL while activity, but it can be implemented for jPDL as well. You can browse the code in the online repository. Look at Loop.execute(). It is much of a hack - you might want to stick to asynchronous continuations unless you need more performance.

      In summary: Does the Timer on Task Node work in jBPM 3.2.3? Does it work in jBPM 3.2.4? (Clarification: the timer seems indeed to expire, but the specified transition is not taken, which results in a stalling process instance)

      Kind regards, Petia