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Re: [wtp-dev] RE: Server API change proposal

Will this work for servers that are able to deploy EAR/WAR by reference to workspace, i.e. actual EAR/WAR structure is not assembled during publish?

Ted Bashor wrote:
One thing I would add is that the Publish process and the Archive Export process should be very, very similar from an extension/api point of view.

For both processes, I’d suggest that the WTP framework should be based on running an ordered list of delegates registered to module/facet id + server/runtime id. WTP would include some default/reference delegate implementations – e.g. ones that assemble an EAR, WAR, or EJB in a directory, ones that deploy to Tomcat, etc.

-Ted

------------------------------------------------------------------------

*From:* Thomas Yip
*Sent:* Monday, March 20, 2006 7:01 PM
*To:* General discussion of project-wide or architectural issues.
*Cc:* Ted Bashor; Konstantin Komissarchik; Gorkem Ercan; Sachin Patel; Timothy Deboer
*Subject:* Server API change proposal


    */Introduction/*

This proposal briefs the limitation we see with current server publish API, and it suggests a solution. We had a short discussion during a conference call on Mar 13^th , 2006. (mainly around the ServerBehaviourDelegate). The problem is also related to https://bugs.eclipse.org/bugs/show_bug.cgi?id=123676


    */Current API/*

We learned the original design was driven by a need of a very simply publish mechanism.

   1. an adopter should able to implement a simply delegate and do the
      publish work.
   2. publish tasks was intent to be simple task.
   3. most methods can be overridden.


    */BEA use-cases/*

We found the current API is not ideal for BEA needs.

We delay much of publish process until user do an explicit publish action (menu item publish, or Run on Server).

   1. We generates *.java file based on annotation of Java file in
      publish time. We trigger project rebuild during process.
   2. We insert information into application descriptors (web.xml,
      application.xml) based on files on the project.
   3. Generated artifacts can cause changes to the EAR or other modules
      in the same application.
   4. Publish application by application.
   5. Publish failure should be isolated between modules.

For us, the publish process is better described as a 3 steps process: Assembly (artifact generation), Packaging (we package virtually), and Distribution (calls JSR-88 to distribute the application to the server).


    */Limitation/*

The current SPI was driven by the need of simple publishing. The publish process iterates module by a flattend module list (not application by application.)

Because that most methods can be overridden, we can achieve our goal reasonably well. However, it incurs maintenance risk, because are not really implementing the delegate’s SPI. For example,

   1. if a fix or an enhancement is made to PublishOperation, our server
      adapter lag behind, and enhancement will not be supported.
   2. We short circuit a few methods, such as publishModules() (which is
      a violate the interface). If any of the methods is called by new
      code that we haven’t overridden, it causes unexpected behaviour.

Because of the different design goal, we don’t implement the full spec of ServerBehaviourDelegate. While such changes might not be likely, an adopter should not be required to implement their delegate in a way to violate the SPI contract.


    */Solution/*


      *Required changes*

We can eliminate the problem by the following changes:

   1. Introduce another delegate. Let’s call it
      BaseServerBehaviourDelegate for now. The current
      ServerBehaviourDelegate should make extended of
      BaseServerBehaviourDelegate. Most generic methods can be push up.
      (such as state settings, module controls, resource delta
      maintaince. But, it leaves out
         1. code related to published module list, and the kind.
            PublishOperation, and
         2. all the publish methods. Introduce an adapter interface to
            indicate PublishOperation is supported.

The changes will maintain compatibility for all current adopter, and the original design goal. It enables adopter with different needs to have full control of the publish process.

2. 1. Either, makes publish operation optional. Push down
            PublsihOperation related code to the original
            ServerBehaviour Delegate.
         2. Or, factors out PublishOperation into utility class or method.
         3. Or, made PublishOperation not depends on the flatten module
            path (IModule[] representing the sub module and its parents).
   3. Introducing another extension point for UI to replace the
      hard-coded publishTask page fragment. Move UI for publishOperation
      as an extension.

A brief study of the code indicated that we should able to implement it in a way that it doesn’t affect existing adopter.


      */Optional changes/*

A few optional changes can be introduced to ease the work of an adopter.

   1. Publishing application-by-application is common to many servers.
      We might want to introduce another BehaviourDelegate.
   2. Generic server is already use application-by-application approach.
      We should look into merging the requirements.
   3. Going further, we can also introduce the 3 steps publish process
      for adopter with complicated publish use-case.

--------------------

Thomas Yip

Senior Software Engineer

BEA Systems

Email: tyip@xxxxxxx <mailto:tyip@xxxxxxx> YIM: thomasleaf Phone: (206) 926-2906 Blog: http://theBigGrid.com/




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