What is the right way to work with persistent sessions and processes?

[mnorsic]

Hi,

I've seen a couple of samples that make use of JPA persistence built into the jBPM5, but I do not understand what is the preferred way to work with persistent knowledge sessions and processes?

For example, I'd like to know when to create a new persistent knowledge session (and its processes)? One ksession for everything? Or maybe one ksession per group of processes that are related to the same fact (eg. if I'm creating a set of processes that manage Person facts, is it normal to create one persistent ksession per Person fact, and create processes on top of that ksession)?

I wonder because if the number of facts per ksession is high, I might have a performance problem when serializing/deserializing facts from database...

Another question: is it possible to use "custom" persistence strategy, e.g. if I want Person object instance from ksession to be stored into a separate table instead into a raw byte array?

Thanks,

Miljenko

[salaboy21]

Hi Miljenko,

Drools and jBPM5 persistence mechanisism let you choose for your particular situation the way of distributing and creating your sessions for your processes. There is not right way to do it. You can create as you mention a session per group of related processes and rules and then start process instances there. You should try to keep your rules well scoped to your processes and for example add your process instance as a Fact so you can filter facts based on the process instance that you are intested into.

About the custom persistence strategies, yes of course! You can use a set of custom marshallers that will persist your Domain objects in a different database or storage using your own entity manager. -> https://github.com/droolsjbpm/jbpm/blob/master/jbpm-persistence-jpa/src/test/java/org/jbpm/persistence/session/VariablePersistenceStrategyTest.java

Look at the method createEnvironment() for more references

Hope it helps!

Cheers

[mnorsic]

Hi Maurizio,

thanks for the tip! I did not look into the jBPM test cases, it would be nice if these persistence test cases be added into a jbpm-examples (or a subset of it, just to show some simple scenarios that work with database).

Thanks,

Miljenko