Christoph Begall wrote:
Hi, I read an article about avalon and it seemed to me like "doing things the right way". I'm not really involved in component technology and I don't think that I understood all of the things that are there, but I would like to go further. I have read developing-with-avalon.pdf, but I don't really know where to go now. I would appreciate hints. Or should I start asking stupid questions like the following on the list? If this is the wrong place to ask just tell me... Some sample questions I would like to learn about: - What is Phoenix, Merlin and Fortress, are they essentially the same, are they all containers? If so which one should I choose?
The are all containers of one form or another.
Phoenix
* basically oriented towards an app-server
* manages deployment of a set of "applications"
* "applicatications" are composed of components
that phoneix assembles based on meta-info
and meta-data
* is released, has some good features like JMX
* is limited to non-embedded applications
Merlin
* next generation container - leverages and enhances
the notion of meta based management from phoenix
* provides support for dynamic component assembly
and deployment
* manages a set of "blocks" (where a block is a container
heirachy that can contain components and other blocks
and is itself a component)
* containers represent the runtime management environment
for the set of components contained within then and
handle the orderly startup and shutdown
* full support for different component lifestyles
* suppport for pluggable lifecycle strategies
* fully embeddable
Foresss
* a container that handles dynamic service activation
(as opposed to predicative in the case of Phoenix
and Merlin)
* container model handles components
* oriented towards the pooled component environment
but provides a full set of compnonent lifestyle
policies
* fully embeddable
There is a process ongoing to get Fortress released - a few things
need to be done (documetation, etc.) first. That release is mainly
providing a replacement for the ECM container. Once Fortess is out
the objective is to converge Fortress runtime management strategies
within the Merlin system and get out as a relase in 3-4 months and
continue a process of container convergence - in particular, the
ability for different contains to interoperation and converge where
possible.
Looking further forward is an action plan for a single container as
part of Avalon 5, focussing on a profile based model using a common
underlying architecture and infrastructure.
Both Phoneix and Merlin provide support for component packaging. Examples of Merlin based packaging is included in a bunch demos that- From the things I read on the mailing list it seems to me, that I could package a component (a block?) in a jar, just like a webapp for tomcat. Is that right? How do I do that?
are included in the CVS (just do a checkout of Avalon, Excalibur and
Sandbox, build merlin, then $ demo).
- If I wrote some kind of network daemon, using TCP/IP connections I could use lots of stuff in excalibur. How can I establish a kind of architecture where some of the classes can be reloaded into the system without stopping the daemon?
This requires a classloader above and beyond the resources available in the JDK or any of the Avalon containers. Merlin lets you do dynamic addition to the classloader but I havn't tried "reloading" a classes that has changed - my gues is that some work would be needed on the type, profile, and appliance libraries (but probably not too much).
I have lots more of those!
Keep em comming! Cheers, Steve.
Thank you for your time.
Christoph.
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