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BPM System Arquiteture Questions

Question asked by louzadod on Nov 8, 2010
Latest reply on Jul 25, 2014 by jkronegg
BPM System Architecture
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Here in our organization we are thinking about BPM as being the driver for
software development.
We are going to build a kind of business portal application.
Each module will be about a different business area (BA).
We need some level of independence (version control, deployment) among BAs.
But we also need some degree of integration towards a unified portal.

We are trying to align our architecture roadmap to the Activiti's one.

Today we are considering the following architectural models:

1) Separated Process Engine per BA:
- share platform JARs (Spring, Activiti, and their dependencies) in a common classloader
- share a datasource pointing to Activiti schema
- isolate each BA in a standard WAR/JEE file
- instantiate a separaded process engine per BA

pros:
  - solves current Class.forName issues in Activiti for invoking Java Tasks.

cons:
  - several ProcessEngines –> higher memory footprint

questions:
  - is there any consistency problem on instantiating several process engines (state, concurrency, caching)?
  - what's the real memory footprint of a process engine instance? Is it a real problem?

2) Single and shared process engine among all BAs
- isolate each BA in a standard WAR/JEE file
- JavaTasks acessible via Rest API (decoupling)
- Process engine also acessible via Rest API

pros:
  - total decoupling between workflow engine and BA
  - shared process engine –> lower memory footprint

cons:
  - JavaTask and process engine invocation latency is higher due to network/http stack
  - need for more access control points (service task is now exposed by http rest interface)

questions:
  - will Activiti be ready in version 5.0 GA to support such Rest model? If not, when?

3) Possible use of OSGi
- Process Engine started as bundle and acessible to other BAs (OSGi service listeners)
- each BA will be an isolated OSGi bundle.
- Process Engine will be able to find BA specific classes (Java Tasks, for example) using, for example,
  "Eclipse-RegisterBuddy" and "Eclipse-BuddyPolicy" manifest headers.

pros:
- Eliminate the need for restful distribution (java tasks, process engine) –> lower latencies –> less need for access control points
- Possibility to redeploy BAs in production in a robust way –> higher availability

cons:
- higher development complexity due to the osgi model (specially if BA uses other libraries not ready for OSGi)

questions:
- When will Activiti be ready for OSGi?
- Which OSGi version will Activiti follow?
- Will Activiti be compliant with


General Questions
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- In general, considering the scenario exposed in the beginning, which of the three models is the recommended and why?

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