Re: Service and Component Frameworks

Jun Yang Mon, 01 Dec 2003 12:52:33 -0800

Weaver, Scott wrote:

What would be the key features that we would be looking for?

This is me speaking, but I am sure others feel the same:

1. Transparent JMX management of deployed modules.

Cornerstone has transparent JMX support for all services. A developer doesn't need to know anything about JMX to get his/her service JMX-enabled. We can add that support to non-service components easily.

2. Hot deploy and hot configuration. No more stop container, change property(ies), restart container, wash, rinse, repeat. Gawd, that's a HUGE PITA!

Cornerstone doesn't have hot configuration. To add it is easy. However, the issue is how do we resolve dependencies cleanly. For example, component A has configuration CfgA. Component B uses a copy of CfgA and adds its own overwrites. We change CfgA at run-time and reload A. We need to know B needs to be reloaded too. We need a clean and simple solution for that. Otherwise reloading the whole thing might be easier and less error-prone.

3. The use of POJOs as components would be a nice feature but isn't really a deal breaker.

All components in Cornerstone are POJOs. We designed for simplicity. In the current implementation of registry, we don't even use XML.

4. Self-contained deployment either via jar or some other container/archive mechanism. Each module would have its own config file included. No more sifting through unwieldy properties files. This also makes updating from the CVS easier you don't have to worry about dif'ing out all the changes you made that will more than likely conflict with the CVS. You obviously have to perform some dif'ing, but in smaller more manageable chunks.

Cornerstone is designed for independently manageable configuration chunks. We need to add this information to the concepts paper. If you look at the registry (code will be available real soon now), we purposefully designed away from centralize configuration files (such as Tomcat's server.xml and web.xml). You don't need to parse a configuration file to find where you need to insert or modify or delete. In Cornerstone you always simply copy over a file to or delete a file from registry in deployment.

Jun

-----Original Message-----
From: David Le Strat [mailto:[EMAIL PROTECTED]
Sent: Saturday, November 29, 2003 11:44 AM
To: Jetspeed Developers List
Subject: Re: Service and Component Frameworks

All,

There is a lot of good info comparing the differences
between frameworks at:

http://wiki.apache.org/geronimo/Architecture_2fKernel

Regarding Hivemind, Howard gave a presentation a while
back, some more info on Hivemind can be found at:
http://www.mail-archive.com/[EMAIL PROTECTED]/msg08269.html

It is a neat framework and hopefully the intellectual
property issue will be resolved soon.  I especially
like the clean interceptor model.  The substitution
model would also be quite handy to create clean
separated modules and substitute common configuration
from a central configuration point. Finally Hivedoc is
quite nice in providing a clear picture of the
dependencies between modules.

Another interesting approach (which is the approach
taken by ExoPortal for instance) would be to combine
AOP with Pico container or Avalon (Merlin seems to be
the recommended service framework).

Lots of choices out there.

What would be the key features that we would be
looking for?

Regards,

David.

--- David Sean Taylor <[EMAIL PROTECTED]> wrote:

Im starting a little informal thread discussing
Service and Component
Frameworks.
Currently we are using Fulcrum in Jetspeed-2.
While I do like Fulcrum and it has been very useful
for us, there are
now more advanced service frameworks available.
All services in J2 are implemented as Common Portlet
Services. The goal
of CPS was to act as a layer so that we could more
easily swap out
Fulcrum in the future. I think that time has come
and we need to start
reviewing the other frameworks and make a decision.
The frameworks we have considering are:
1. Hivemind
2. Pico Container
3. Jetspeed Cornerstone (not to be confused with
Avalon Cornerstone)
4. Avalon
I really like what I've seen in Hivemind, however the current licensing issues concern me. I also think that Cornerstone, contributed by the Cisco team to Jetspeed, is very powerful. Are there other service frameworks we should be considering?

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