Add pomfirst build + add K3FSM example MEP server

[dvojtise]

This PR contributes to the addition of a Model Execution Protocol implementation in GEMOC.

The generic part of the MEP framework is contained in eclipse-gemoc/gemoc-studio-modeldebugging#169 and a specific implementation for K3 is contained in eclipse-gemoc/gemoc-studio-execution-java#7.

This PR :

• adds a new pomfirst build entry point in dev_support/pomfirst/pom.xml allowing to build all GEMOC pomfirst projects in a single command (similar to dev_support/full_compilation/pom.xml that applies to tycho based builds)
• adds a Model Execution Protocol server project to the K3FSM official example as an example of the K3MEP server of Initial version of a Model Execution Protocol framework for GEMOC gemoc-studio-execution-java#7. Ie. It implements the org.eclipse.gemoc.executionframework.mep and org.eclipse.gemoc.execution.sequential.javaengine.headless by connecting the K3FSM dsl to the engine and presents it via a quarkus based websocket server. (this example should not be here but this is another issue Move official examples dedicated to one engine directly in the engine repo #210)

[ebousse]

What I don't get is why is the title "Initial version of Model Execution Protocol framework for GEMOC" while the first sentence states "This PR adds a Model Execution Protocol server to the K3FSM official example"?

Does the PR add the generic protocol, or simply a PoC specific to K3FSM?

[dvojtise]

You're right this work is currently more a POC than an API introduction. This is because only one engine is offered, and I (and @pjeanjean) have questions about how to further deploy this to other engine.
Actually, this works raises several questions (at least even me who provided it, have some questions about it) about our strategy and future work to improve it.

1/ First point, the MEP engine is NOT the same as the one used in the gemoc modeling workbench for the same task.

2/ one of the requirement was to have a pure java (non osgi based) implementation (smaller footprint and faster startup time). We may consider the relation with the previous headless studio (osgi based) that is also without UI. The pure java version seems to work but is quite fragile about version management. Additionally, managing jar with maven dependencies also add some complexity to the development (even if only some jars are handled that way)
However, this PR is a start for a subset of GEMOC components that can be used without OSGI.

3/ what about adding MEP capabilities to every engine ? In future work, we may consider removing the debug addon and replace it completely by MEP so the entire UI would just connect to it.
This would remove the need of having 2 engines per metaprog approach

4/ current MEP doesn't support backward navigation because there is no trace management in the pure maven (current trace management is implemented as addon) we probably need either choose to stay in osgi or find another injection mechanism for the core features (debug and trace) that would work in both modes.

Depending on the direction we chose, several of these points may require some major development effort...

[dvojtise]

I'll open a thread in the gemoc-dev mailing list about the above points.

About your question about the title, may be just rename it

"Initial version of a Model Execution Protocol framework and implementation for GEMOC" ?

[ebousse]

I'll open a thread in the gemoc-dev mailing list about the above points.

Sounds good.

About your question about the title, may be just rename it

"Initial version of a Model Execution Protocol framework and implementation for GEMOC" ?

My problem is more about the fact that the PR says it's about "K3FSM", hence a single xDSL, while the title of the PR is about the whole GEMOC Studio.

[dvojtise]

A part is generic and can be reused for every approach (content of eclipse-gemoc/gemoc-studio-modeldebugging#169 , and enabling the build management as pomfirst in this PR), and the current assembly of all 3 PRs which contains only one complete implementation (in eclipse-gemoc/gemoc-studio-execution-java#7 + this PR with the concrete example)

[dvojtise]

I've refined the general description, tell me if its cleared

[ebousse]

Much better, thanks! :)

but then it's the title of the PR that should be changed, no? Maybe something like:

Add pomfirst build + add K3FSM example MEP server