topic Re: Adding a dynamic step while the instance is in flight in Alfresco Archive

Adding a dynamic step while the instance is in flight

dilipl1 — Wed, 25 Apr 2012 20:48:26 GMT

I have been evaluating Activitii to see if it helps us achieve what we are trying to accomplish.Essentially we want the ability to add a dynamic step (available to be picked up from a list of steps) at any point in the process thereby affecting the instance in flight. The step can be added anywhere

Re: Adding a dynamic step while the instance is in flight

dilipl1 — Thu, 26 Apr 2012 21:08:33 GMT

Like, illustrated in this blog. Is this possible with activiti 5.9? Really appreciate if the stalwarts here respond. We are trying to see if we need to build our own workflow engine or if activiti will satisfy this crucial requirement.

http://mauricedechateau.blogspot.com/2010/07/adding-task-nodes-dynamically-at.html

Mainly we want to add a dynamic step (out of a step library) at any point of the process for the current instance. This will happen not too often in production but is a crucial requirement.

Thank you guys.

Re: Adding a dynamic step while the instance is in flight

croc1 — Fri, 27 Apr 2012 00:49:10 GMT

I want to ask this question too!

Re: Adding a dynamic step while the instance is in flight

meyerd — Fri, 27 Apr 2012 05:41:18 GMT

Hi dilipl and croc,

Consider that the process definition is static and we literally reuse the same instance of a process definition object for each instance at runtime (see DeploymentCache).
So if you modify the PD, the modification will be propagated to *all* running instances in that process engine instance.

What you can already do is, if you have a UserTask, you can add dynamic subtasks at runtime. These will be properly linked to the given "parent" task in the process definition.

Other than that what you could do is add a set of tasks to the process definition which are not related to the "main" flow of the process (have no incoming / outgoing sequence flows, and then in a custom ActivityBehavior you set the execution to one of these tasks and continue there.
So that would look somewhat like this: (warning: untested pseudo-code):


String dynamicActivityId = "myDynamiyAct";
ActivityImpl dynamicActivity = processDefinition.findActivityById(dynamicActivityID);
execution.setActivity(dynamicActivity);
AtomicOperation.ACTIVITY_START.execute(execution);

This will get you to the activity. Note that if the activiti is a scope, this will not create a new scope execution. Also in other respects, it is a very dirty hack.

So I guess It is always possible to do something like this, but you have to weigh whether you are willing to pay the price. I would advise against, in most cases.

Re: Adding a dynamic step while the instance is in flight

dilipl1 — Tue, 01 May 2012 02:39:19 GMT

Thanks for your response meyerd.

I am going to try both these approaches and do a demo and see if this works. Here's a couple of questions

1) The subtask approach
a) When a subtask is added under an already present task (usertask or servicetask correct?) at runtime, I will need a spring bean associated with it (java delegate). The user will only be able to pick from a fixed set of tasks (to make it a subtask). Is this possible? Can I have some a spring bean associated with a dynamic subtask?

2) Disconnected tasks present in the process
With the second approach, I don't like all the tasks just sitting in the process either, but I can see where I can have a spring bean associated with it since the task will be present in the process.

I like approach 1 as it eliminates the litter, but can I associate a spring bean with a dynamic subtask?

Thanks so much

Re: Adding a dynamic step while the instance is in flight

dilipl1 — Fri, 11 May 2012 03:31:57 GMT

Hey everyone and meyerd,

I am trying to do what you indicated in strategy 2 above since subtasks don't work. So, say I am at step 1 in my current execution and I want to add step 3.5.

step 1 –> step 2 –> step 3 –>step 3.5–> step 4

I do not want to go to step 3.5 yet. I just want to add it. I am at step 1 right now
ActivityImpl dynamicActivity = processDefinition.findActivityById("step3.5");

Now how do I change transitions from 3 to 3.5 and 3.5 to 4 instead of 3 to 4??

All help is appreciated

Re: Adding a dynamic step while the instance is in flight

nemesis1 — Fri, 11 May 2012 06:57:53 GMT

Hi,

I want to add another question. I draw a process which has seperate tasks (no incoming, no outgoing sequence flows), some task collections so that I can visualize my questions.

Is it possible

-when I am in user task 2 in main process, can I go to another task except main process. (for example user task 6 or collection 1) After I complete this task can I return to main process to complete remaining process.
-Is it possible to form process fragments as collection 1 or collection2. If it is possible, can I return to main process. (I see an example on drools and they call it as ad-hoc.)
-If I can form collections, is it necessary to put end event or start event.
-Maybe it should be the main question. Does activity designer support seperate tasks in process.

Our main aim is to supply flexibility to users. In another topic, I asked you when noninterrupting and interrupting boundary event will be supported. I think this wil also supply flexibility to users.

Thanks.

Re: Adding a dynamic step while the instance is in flight

dilipl1 — Fri, 11 May 2012 15:24:49 GMT

Hey Activiti gurus,

Can someone please chime in to my question and then nemesis'

Here is some code, that helps me get an instance and then the process definition. I then get the activity (task). However I do not know the right way to change transitions to add step3.5 from my post above.

step 1 –> step 2 –> step 3 –>step 3.5–> step 4


ProcessInstance processInstance = runtimeService.createProcessInstanceQuery().singleResult();
ProcessDefinitionEntity pd = (ProcessDefinitionEntity) repositoryService.createProcessDefinitionQuery()
    .processDefinitionId(processInstance.getProcessDefinitionId()).singleResult();
ActivityImpl dynamicActivity = pd.findActivity("step3.5");
ActivityImpl afterActivity = pd.findActivity("step3");

Thank you and appreciate all your inputs. If I can do this, it will help me sell activiti to my team.

Re: Adding a dynamic step while the instance is in flight

ronald_van_kuij — Fri, 11 May 2012 16:24:25 GMT

when modifyin the definition, it is for all instances…!!!

why not add dynamic 'subprocesses' at the places where you want some dynamic things to take place? what 'subprocess' will be executed can be decided runtime. that can eithe be some predefined and deployed ones, or even one you create runtime.

Re: Adding a dynamic step while the instance is in flight

dilipl1 — Fri, 11 May 2012 17:40:28 GMT

Hey Ronald,

I actually checked out the functionality (there is even a test in activiti examples) to pick a subprocess at runtime.
However what we (and many others) want is the capability to add a task at any point and not at a predefined spot. I will give you an example.

Consider my diagram with steps 1 thru 4 above and my current execution is on step 1. Now a plant engineer, for just one work-order (instance) wants to go in and add a step 3.5. Just as likely, they could have added step 2.5. So I can't have subrocesses called at predefined steps.

What do you think Ronald? Any way to accomplish this?

Re: Adding a dynamic step while the instance is in flight

meyerd — Sat, 12 May 2012 15:58:14 GMT

Hi Guys,

some of what's discussed here closely resembles the concept of the "ad-hoc subprocess" as specified by bpmn. While supporting the ad-hoc subprocess is not the most prominent item on the roadmap (at least not with us at camunda), there is of course always the possibility of sponsored development http://www.camunda.com/consulting/activiti/sponsored-development/.

Re: Adding a dynamic step while the instance is in flight

nemesis1 — Sat, 12 May 2012 20:17:47 GMT

Hi meyerd;

Apologize for my blurry question. Essentially we are trying to understand the limit of activitybehaviour.
my main question is;
Is it possible to jump to another task in a process.

How can I obtain detailed information about sponsored development? We can need this if we decide to have an adhoc sub process.

Thanks.

Re: Adding a dynamic step while the instance is in flight

ankhara33 — Fri, 26 Apr 2013 21:49:10 GMT

nemesis, yes of course it's possible…. We use logic to skip all the tasks we don't want at executing time by variable values, and target the correct one. A process instance variable is used in the runtime execution to determine if we should create an activiti task or not… and access it through a CDATA tag.. like below… of course I can't post all the pieces here, but should give you an idea …

Here's what a snippet of what our process looks like at any of the 'determine' if we should skip or goto the next task …
<code>
<sequenceFlow id="checkCustodianApproval_checkAssetAllowed" name="approved" sourceRef="isCustodianApproved" targetRef="isCustodianAllowedToHaveAsset">
<conditionExpression xsi:type="tFormalExpression"><![CDATA[${approved == true}]]></conditionExpression>
</sequenceFlow>
</code>
Approved is set in the process runtime by a Java TaskListener that sets it with something like this:
delegateTask.getExecution().setVariable("approved", "true");

Ankhara