[rules-users] Drools flow ; events with AND join , persistence for flows, being able to suspend and resume flows, and long wait states

[shoukry kattan]

Dear All,

I have been evaluating a number of frameworks including jBPM and Drools flow
for my application requirements. Lots of the opinions seem to be inclined
towards Drools flow as its more flexible, knowledge oriented, easier to
integrate with business rules, etc..

The application is some sort of an Email Campaign manager , where different
customers can sign in, prepare (design) and launch email campaigns.

The application should be able to do the following :

1- Receive a list of email addresses, send emails to each of these addresses
starting from a certain date and during a certain time interval of the day ,
do some custom actions, and then wait for reply emails.
2- If a reply email is received  and depending on the response text of the
email , and depending on the time the email was received certain actions
need to happen, web service calls need to take place, and error handling for
these calls.
3- The application will manage and run many and different campaigns
(different customers and different flows for each customer) at any point of
time.


*The first question is : *
Is Drools flow the way to go about this?
My main concerns are scalability, suspending, resuming flows, and long wait,
and flows management.

As you see from the requirements :
*There is a scheduling part :*
Certain flows need to be run at a certain point in time, they need to get
suspended and then resumed.
For example start sending emails starting on Dec 1st 2010  and send emails
only in the time interval between 08:00  and 17:00 GMT. By then it might be
that all subscribers have been sent emails, but it might not be the case,
the process needs to (resume) on Dec 2nd and send a second batch, however
certain (users) already received emails and they should be able to (continue
at different stages of the flow)

*There are long wait states : *
Days or even weeks , i need to persist, suspend / resume and terminate flows
(manage flows)

*External Events :
*
This is where i got stuck first, i tried to put together a simple flow (see
attached screenshot) , there is a start node , connected to an action node,
connected to a join.
An event node is connected to a second action node, which is connected to
the join. The join is an AND join , after the join there is an action and
the end node.

Here is the sample code i am using to launch the flow :


        KnowledgeBuilder builder = KnowledgeBuilderFactory
                .newKnowledgeBuilder();
        builder.add(ResourceFactory.newClassPathResource("campaign.rf",
                CampaignsDroolsPoc.class), ResourceType.DRF);

        if (builder.hasErrors()) {
            KnowledgeBuilderErrors errors = builder.getErrors();
            Iterator<KnowledgeBuilderError> iterator = errors.iterator();
            while (iterator.hasNext()) {
                System.out.println(iterator.next().toString());
            }

        }

        KnowledgeBase base = KnowledgeBaseFactory.newKnowledgeBase();
        base.addKnowledgePackages(builder.getKnowledgePackages());

        final StatefulKnowledgeSession ksession = base
                .newStatefulKnowledgeSession();

        // KnowledgeRuntimeLoggerFactory.newConsoleLogger(ksession);

        ksession.getWorkItemManager().registerWorkItemHandler("Log",
                new SendSMSWorkItemHandler());

        ProcessInstance startProcess = ksession.startProcess("flow");

        System.out.println("Signaling event");

        startProcess.signalEvent("ev1", "ev1");

        System.out.println("Signaled");

        ksession.fireUntilHalt();


I am noticing that the event get triggered, the action node connected to the
event gets triggered, however things seem to get stuck at the join. The flow
does not continue past the AND join and the flow seems to get stuck. The
action following the node does not get triggered.

I have seen the post about the Manufacturing process , however there is no
code sample of how this guy got that to work.
http://drools-java-rules-engine.46999.n3.nabble.com/DROOLS-Flow-as-a-Manufacturing-process-execution-engine-Noob-questions-about-events-and-concurrency-td706102.html

I also went through the drools flow documentation , and all the example
codes, however i didn't find anything there.

In addition any hints about the way to go about architecting the solution,
and implementing it would be great.

While googling I noticed that there are many more jBPM examples than drools
flow and this is not so good for guys like me trying to get started.
If you help me guys I would be glad to post the entire Proof of concept I am
working on as a drools flow example.


Regards,

Shoukry Kattan
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