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From David Le Strat <dlest...@yahoo.com>
Subject Re: [JETSPEED 2] Service framework progress
Date Sun, 15 Feb 2004 21:33:43 GMT
Sami,

Thanks for your feedback. I don't think you are too
late.  Last time I looked at Spring there was not a
clear separation of the core.  However in RC1, this
seems to have changed.  They also seem to have
separated out the context part which is interesting.

I made some comments below.

David.

--- Sami Leino <sami.leino@netorek.fi> wrote:
> I was finally able to catch up with the developer
> list postings sent after
> Nov 2003. I'm propably late with this, since the
> most active discussion
> has already passed by. If I'm late, just discard the
> message and don't
> bother answering.

After many debates, we are getting to the point where
we are close to getting the work started. Jun and Emad
have done a great job at creating a nice JMX module. 
Now, we need to move to the core.  Decisions are being
made now.

> 
> Here are the questions I would like to ask:
> 
> 1) I got the impression that you have decided to use
> PicoContainer as the
> underlying service framework, possibly using a
> common services layer
> and/or Jetspeed-Cornerstone to hide it's presence.
> Am I correct?

That's the direction we are moving towards. Please
find enclosed some notes summarizing (not exhaustive
though) multiple brainstorming sessions with Scott,
David, Jun and others.

The definition of service is quite broad and we are
moving towards:

1. Any number of component containers
(through pico or whatever). These are components NOT
services.  We would be possibly looking at supporting
multiple containers.  Can you do this with Spring? Can
you have multiple Spring containers running?

2. Services which fall into request in /
response out.

Conerstone for "services" makes sense where
Cornerstone provides Orchestration + JMX + web
services support for multiple transports (http, JMS,
etc.).

We would also like to add events and/or AOP "around"
service invocation (transparent to the service as part
of the component framework).

What is your experience with Spring and how would it
enable events + AOP around service invocation?  Why
would you use Spring AOP?

We need still need to formalize several thing:

- The root concept.  Instead of one application root,
support 1..n and have properties be relative to a root

- The distinction between different kinds of services:
 - formal Java services that equate to a Java class.
 - WSDL-like services, which basically define an
end-point.

Any ideas in that regard?

> 
> 2) You seem to have arranged an IRC session on Feb
> 10 about the service
> framework issues. Is there a log available anywhere
> on the net?

We probably need to formalize a proposal. I know that
David started to work on something.

> 
> 3) Did anyone construct a full comparison chart at
> any phase listing the
> pros and cons of alternative frameworks?

We have done some of that.  You can look in CVS at
/docs/J2ServiceFramework.  The landscape changes
quickly though.

> 
> 4) Have you been able to set up a component
> acquire/release policy
> already? Of course it's not an issue at all if you
> will only provide
> singletons, but it's a major issue if your framework
> delivers pooled
> instances as well. Have you found any frameworks
> containing some kind of
> support for automatic releasing?

Not explored at this point.  Some suggestions?

> 
> 5) What kind of scheduling support there will be?
> 
> About comparing frameworks: I found this comparison
> about Spring and
> PicoContainer on the net. I presume you all have
> read this before, but
> here it is anyway:
> 
>  
>
http://www.springframework.org/docs/lightweight_container.html
> 
> The chapter 6 compares Spring and PicoContainer. I
> presume you are aware
> of PicoContainer's characteristics already, and you
> won't see the listed
> issues as major drawbacks, like I do. But, I think
> one can live with them
> - they just make your life a bit harder.
> 
> Spring, on the otherhand, seems to include many
> things that aren't needed
> by most of us. I'm not sure if there is a proper
> separation between the
> core microkernel and other features (like support
> for AOP, MVC,
> transactions and so on) - there certainly should be.
> Otherwise, the
> framework won't be widely adopted.

RC1 seems to be addressing these.  We are now at a
point where we need to make a decision.  It is
actually a good time to voice your opinion.  Speaking
for myself, I am always looking forward to
constructive and well articulated feedback like yours.

I hope that helps.

Regards, 

David Le Strat.

> 
> Again, I apologize for being this late.
> 
> Sami
> 
> -- 
> 
> Sami Leino
> Software Developer
> Netorek Oy
> 
>
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