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Re: [architecture] Fractal packaging & deployment, bis


I won't claim to understand everything in the packaging document, but I will try to comment on what I do understand.

First, the choice of the word "package" is a significant source of confusion, perhaps something like "deployment unit" would be better.

I have to assume that the document is trying to be programming language/environment neutral, which probably leads to much of my confusion when reading it. Is the goal to create a generic packaging approach that can be implemented in any language, like the Fractal spec itself, or is the goal to define a packaging approach for Fractal on Java?

Speaking from a Java perspective, I see three layers (or pieces):

  1. A foundation layer for managing/deploying file-based "deployment
     units" based on packages,
  2. A second layer that maps the file-based deployment units into
     class loaders, and
  3. A third layer that maps these concepts into a target component model.

Layers 1 and 2 can perhaps be combined, but they should be component model agnostic; they should provide features that the third layer can use to embed meta-data, policies, and so on for any component model. In this approach, layers 1 and 2 are purely middleware.

Again, I admit that I don't really fully comprehend the packaging document, so perhaps my comments are off-base, but I think more thought has to be placed into the requirements of the lower level deployment layers.

Interestingly, I just attended my first OSGi meeting last week and this is precisely the issue that they are wrestling with now; they are wondering if it is possible to separate the deployment aspects from the life cycle and service aspects so that they might be usable independently. This is something I highly encouraged, especially since Oscar tries to follow this same goal to varying degrees of success.

I am not sure how much I am allowed to comment on these issues, but I think the idea of providing a generic deployment "module" layer for Java is an ultimate middleware goal, since Java lacks a viable alternative to something like assemblies and the GAC in .NET.

An excellent paper in this area is:

   http://pag.lcs.mit.edu/reading-group/corwin03mj.pdf

A guy from the group where the above above project was done in IBM is now participating in OSGi, which gives me great hope for their seriousness in creating such a module deployment layer for Java. I think this is the right approach.

Sorry if my comments are too Java-centric...

-> richard

Eric Bruneton wrote:

to continue the "discussion" on this topic (in fact we got very little feedback), here is a document that summarizes the result of a meeting on this subject that took place last week, between INRIA and FTR&D. Comments are more than welcome, they are needed!

the DREAM and Fractal teams



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