Shared objects across activities about flogo-lib

[fm-tibco]

Thanks Adirio. Shortly I'm going to start looking into both how best to share resources and also possible activity initialization based on both app and the particular action/flow it belongs to. I'll keep you posted.

[Adirio]

As suggested in #111 in this comment, different scopes of shared resources could be implemented, being the activity attributes a natural one, and flow and application level two more that may be interesting.

[Adirio]

Some thoughts: Working on another project I thought that context could be used for this. A ctx could be passed though activity.Init() and trigger.Init() to populate it with the shared resources. Then this context would be passed to trigger.Start() instead of creating a new one from context.Background() and it should also be passed to trigger.Stop() and activity.Eval().

[Adirio]

I've realised that what you are passing to activity.Eval(), despite being named activity.Context it is not a context.Context as I was expecting (similar to the extra abstraction layer you are using on trigger.NewContext). Is the activity.Context an abstraction layer over context.Context or is it a completely different thing? Because my thought was based on the fact that you were already passing some kind of context.Context to activity.Eval().