topic Re: What's the best way to design a process which allows user to recall back to his task. in Alfresco Archive

What's the best way to design a process which allows user to recall back to his task.

chenning007 — Thu, 15 Jan 2015 02:59:07 GMT

Hi folks,I am not sure this is the proper place to raise this question, if not please kindly let me know.My question: is it possible for activiti engine to allow user to recall back to his task, for examplestart -> task A -> task B -> task C -> endif task A is completed by user A, proces

Re: What's the best way to design a process which allows user to recall back to his task.

chenning007 — Thu, 15 Jan 2015 03:09:06 GMT

any comments please, I am waiting online

Re: What's the best way to design a process which allows user to recall back to his task.

trademak — Fri, 16 Jan 2015 11:46:21 GMT

Hi,

You could use a signal boundary event on every task for example, that moves back to the previous task. You can then signal the process instance when necessary.

Best regards,

Re: What's the best way to design a process which allows user to recall back to his task.

chenning007 — Tue, 20 Jan 2015 07:23:17 GMT

Tijs,

Thanks for your reply…

Your proposal sounds a good idea to me, now we meet another trouble – we would allow to recall a task to any tasks which previously had been completed, for example, users who completed task A, B, C, D would require to recall current task E back to one of their tasks which would be task A, B, C or D.

Our current solution is to draw flow lines from task E to task A, B, C, D, but it results in a very big process(many flow lines) which is hard to be maintained. Based on your proposal, can we send the jump-back task name within the signal, when the signal is replied by boundary event, an new implemented service task which can parse target task from the received signal and jump the process back to target task directly. What's your idea on this solution, if you have anything better, please also advise, thank you.

–Ning

Re: What's the best way to design a process which allows user to recall back to his task.

martin_grofcik — Wed, 21 Jan 2015 08:08:02 GMT

Hi Ning,

Another possibility could be to do not cover return back in process definition, but support it in admin functionality. (Command to take execution end return it to the state where you want to. (It is easy to do in activiti).

Regards
Martin

Re: What's the best way to design a process which allows user to recall back to his task.

chenning007 — Wed, 21 Jan 2015 09:34:57 GMT

Hi Martin,

I suppose the command you mentioned here is the internal implementation of xxxService classes(activiti API). Can these commands class be accessed by application directly, or I should implement my own customized API based on these command classes for this specific requirement?

Thanks!

–Ning

Re: What's the best way to design a process which allows user to recall back to his task.

jbarrez — Wed, 21 Jan 2015 13:56:12 GMT

You can write custom Commands and pass these in the ManagementService.

Re: What's the best way to design a process which allows user to recall back to his task.

tloomba — Tue, 31 May 2016 00:50:45 GMT

Hi Mr. Joram,

would you have an example of how to write a custom Command and use it for the above use case? I work in a company where the use case is similar. We have very large process models and our customer has the need to send the existing process instance upstream to a previous step, or downstream to a step that has not executed yet. Drawing transitions in the model will clutter them and not be scalable, especially when new models are created. If you could provide us with an example of using a custom Command, that would help as we have searched the forum and the web and did not find examples of creating custom Command.

Also, one of the customer's use case is to complete a process instance gracefully, as if it had ended as normal. If the instance is a sub-process created from a call activity of a parent process, the parent call activity should complete and instance should move to next step. We found the following example code from this forum, but it is throwing a null pointer exception at the "exec.end()" call. Would you be able to provide some information on why Activiti is throwing an NPE at this call? I would assume of ActivityExecution provides an end method, it should work.

This is the code we tested:

List<Execution> executions = runtimeService.createExecutionQuery().processDefinitionName("TestSendTo").list();
ActivityExecution exec = (ActivityExecution) executions.get(0);
exec.end();

Below is the exception:

org.activiti.rest.exception.ExceptionHandlerAdvice - Unhandled exception
java.lang.NullPointerException
at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperationSync(ExecutionEntity.java:633)
at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:628)
at org.activiti.engine.impl.persistence.entity.ExecutionEntity.end(ExecutionEntity.java:398)
at com.thomsonreuters.workflowservice.service.SendToServiceImpl.completeInstances(SendToServiceImpl.java:105)

Any information you provide would be helpful. Thank you in advance of your time!

Tavishi Loomba

Re: What's the best way to design a process which allows user to recall back to his task.

martin_grofcik — Tue, 31 May 2016 06:38:54 GMT

Hi,

would you have an example of how to write a custom Command and use it for the above use case?

An example of the new command usage:


    public void setExecutionToActivity(String executionId, String activityId) {
        ProcessEngineConfigurationImpl processEngineConfiguration = …..
        processEngineConfiguration.getCommandExecutor().execute(new SetActivityCmd(executionId, activityId));
    }
….
    private static class SetActivityCmd implements Command<Void> {

        private final String executionId;
        private final String activityId;

        private SetActivityCmd(String executionId, String activityId) {
            this.executionId = executionId;
            this.activityId = activityId;
        }

        @Override
        public Void execute(CommandContext commandContext) {
            ExecutionEntity execution = commandContext.getExecutionEntityManager().findExecutionById(this.executionId);
            execution.setActivity(new ActivityImpl(this.activityId, execution.getProcessDefinition()));
            return null;
        }

    }

Regarding deleting process instances:


/**
   * Delete an existing runtime process instance.
   * 
   * @param processInstanceId
   *          id of process instance to delete, cannot be null.
   * @param deleteReason
   *          reason for deleting, can be null.
   * @throws ActivitiObjectNotFoundException
   *           when no process instance is found with the given id.
   */
  void deleteProcessInstance(String processInstanceId, String deleteReason);

NPE stack trace does not make sense without activiti version (It is not Activiti6 master branch 🙂 ) Can you create simple jUnit test?
https://forums.activiti.org/content/sticky-how-write-unit-test

Regards
Martin

Re: What's the best way to design a process which allows user to recall back to his task.

tloomba — Mon, 13 Jun 2016 01:35:33 GMT

Hi Martin,

thank you very much for providing an example of creating and implementing a custom command. This worked well to the extent that the custom command does get executed without any errors. I tried the example you provided above, which is set the activity id of the current execution to the desired activity where we'd like to re-route the execution too. The execution however just sits at that activity without moving downstream. Is there a new job that needs to be created after setting the activity id? My main goal is to set the new activity id but also have the execution route to that activity and move downstream from there. Would you please tell us know how to do that?

Thank you very much for your help!

Tavishi Loomba

Re: What's the best way to design a process which allows user to recall back to his task.

martin_grofcik — Mon, 13 Jun 2016 08:15:10 GMT

Hi Tavish,

The execution however just sits at that activity without moving downstream.

In the case when you wan to run the execution, you have to signal it.
e.g.:


getCommandExecutor().execute(new SignalCmd(executionId, signalName, null,
                null));

Regards
Martin

Re: What's the best way to design a process which allows user to recall back to his task.

tloomba — Mon, 13 Jun 2016 22:26:09 GMT

Hi Martin,

thank you again! What should be the value of the signalName parameter in the constructor call for SignalCmd? We tried null as signalName and also "compensationDone" which we found in various forum posts, but neither worked.

Also, will sending the Signal to the execution be enough to run the execution further, or are there additional commands we should invoke? I regret having to keep coming back to you for additional questions. There is no javadoc on classes such as SignalCmd, Command classes. We have spent lot of time searching Activiti forums and the web, but are not finding any concrete examples or documentation. Does documentation exist for how such design patterns (for example custom Command) should be implemented?

We are using Activiti version 5.19.

Thanks!
Tavishi

Re: What's the best way to design a process which allows user to recall back to his task.

martin_grofcik — Tue, 14 Jun 2016 06:54:10 GMT

Hi Tavishi,

The best would be to create jUnit test as an example. When I will have a time I can create one. (Or you can help me too -> just prepare what you have to the jUnit test template https://forums.activiti.org/content/sticky-how-write-unit-test and I can add what is missing.)

Regards
Martin

Re: What's the best way to design a process which allows user to recall back to his task.

tloomba — Thu, 16 Jun 2016 20:30:52 GMT

Thank you! Yes, I will prepare one and have it available by tomorrow. Does it matter that our project uses Sping Data JPA version 1.8 and Hibernate JPA version 2.0 with Activiti version 5.19? Can my unit test only include the H2 db configuration, or will it make a difference to the design implementation?

Also, how do I submit the unit test to you?

Re: What's the best way to design a process which allows user to recall back to his task.

jbarrez — Wed, 22 Jun 2016 08:04:03 GMT

As long as we can run it easily, that's the main goal. H2 is preferred, yes.

> Also, how do I submit the unit test to you?

Github repo is the easiest

Re: What's the best way to design a process which allows user to recall back to his task.

evavilaginés — Wed, 29 Jun 2016 11:59:41 GMT

Hi,
I'm very interested in this post because just I have to implement the "reverse" in a flow of activiti (to allow user to recall back to his task and forward).

Is there any available example of the solution described here? Or another better solution?

I have tried to implement the solution described here but not get it to work (I'm new programming in activiti) .

Any help is welcome.

Thank you very much,

Re: What's the best way to design a process which allows user to recall back to his task.

martin_grofcik — Thu, 30 Jun 2016 06:34:15 GMT

Hi,

you can wait on Tavishi's jUnit test our you can create your own, and we can work on the example together.
https://forums.activiti.org/content/sticky-how-write-unit-test

Regards
Martin

Re: What's the best way to design a process which allows user to recall back to his task.

tloomba — Thu, 21 Jul 2016 22:55:15 GMT

Martin and Joram,

Thank you very much for your responses. I will creating and posting the Junit test in a couple of weeks. I really appreciate your input and help.

Thanks!
Tavishi

Re: What's the best way to design a process which allows user to recall back to his task.

tloomba — Thu, 11 Aug 2016 21:53:05 GMT

Hi Martin,

I created the unit test in the maven project template your team provides. Please download "SendToActivitiUnitTest.zip" from https://github.com/tloomba/SendToTestTavishi. As a recap, following is the use case I am trying to achieve:

Re-route a process instance from a downstream step where it is stopped at a wait state to a previous upstream step, and have the execution move downstream based on the transition conditions, as it normally would the first time it entered the upstream step. In the attached project I created a sample process called TestSendTo.bpmn. In this process the first wait state the execution could stop at is User Task 1. When the execution moves downstream it could stop at User Task 2, and further downstream it will always stop at Receive Task. Following are the types of re-routing use cases I would like to achieve:

1) When the process has moved downstream and stopped at Receive Task, re-route it to Service Task 1. The execution should move downstream from Service Task 1 as it normally would, based on the transition conditions.

2) If the process has moved downstream and stopped at User Task 2, re-route it to Service Task 1. The execution should move downstream from Service Task 1 as it normally would, based on the transition conditions.

3) If the process has moved downstream and stopped at User Task 2, re-route to User Task 1. The execution should move downstream from User Task 1 once it is completed, as it normally would, based on the transition conditions.

Just to clarify again, our goal is to achieve above use cases without drawing transitions in the process model. I added a unit test in MyUnitTest.java which attempts use case #1. As you see I created a custom command with the code you provided above on May 31st. I invoked the custom command to achieve the re-routing from Receive Task to Service Task 1, and then signaled the command as you suggested above using the line:

"commandExecutor.execute(new SignalCmd(task.getExecutionId(), "compensationDone", null, null))"

The process instance should now have moved to User Task 1 since the variable 'goToUserTask' was set to true. However, if you execute the unit test you will notice at line 68 when we retrieve the process instance again, it seems to have stopped at Service Task 1 and does not move downstream. We did not know what should be the value of the "signalName" parameter for SignalCmd constructor. Our project is depending on the satisfaction of these use cases for the success of the project, and we also are nearing our deadline in a few weeks. I'd have immense gratitude if you are able to review this and get back to me at your earliest convenience!

Thanks,
Tavishi

Re: What's the best way to design a process which allows user to recall back to his task.

tloomba — Tue, 16 Aug 2016 23:35:48 GMT

Hello Martin, Activiti team,

could I please request you to review the above unit test I posted and my questions as soon as you are available? We are on a crunched time-line for our project to develop this use case and your input is very critical for us. I regret any inconvenience caused.

Thanks!
Tavishi