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From Aaron Mulder <ammul...@alumni.princeton.edu>
Subject Re: Management object model questions
Date Fri, 30 Sep 2005 03:43:17 GMT
On 9/29/05, Joe Bohn <joe.bohn@earthlink.net> wrote:
> I'm having a difficult time getting my head around the management object
> model.   As I understand it we have one J2EEServer in a G image which
> can be queried to return multiple WebManagers (actually the web manager
> lookup is done using the interface specified on the GBeans ... so
> there's nothing really unique about the J2EEServer doing this).

If we go to a clustered environment, there will be one domain and
multiple J2EEServers.  Likewise, there would be multiple kernels.  So
lookups of specific per-node properties should happen at either the
J2EEServer (or possibly JVM) level.  That's why the WebManagers are
accessed via J2EEServer.

> The WebManagers act as a type of collection point for all of the
> WebContainers, Connectors, etc...  However, when it comes to web
> containers the WebManagers appear to be container specific (they will
> always only manage containers of the same type) and there can be only
> one WebManager instance per container type in the system.  This implies
> to me that we do in fact intend to support any number of web containers
> types.  Also within the WebManager for a specific container type we  can
> support any number of web container instances of that type.  This
> implies that we intend to support not only a single instance of multiple
> web container types but also multiple instances of web containers of the
> same type.  Is this correct and is that really the intention?

Yes.  I'm not sure how likely it is to have two Tomcat containers
running, but the intention was to not rule it out.  WebManager is
specific to a container implementation (Tomcat or Jetty), but not to a
container.

> Other questions:
> - JSR77 is primarily concerned with the management of applications and
> not the server or its components.  In fact, the configuration management
> is specifically listed as being outside of the scope of the spec.
> Therefore the representation of objects to manage the server itself, web
> containers, ejb containers, etc... are G specific creations - right (or
> is there some other specification that I'm missing)?

Right.  Well, mostly right -- JSR-77 defines J2EEServer, but not
WebManager, for example.

> - The way that we are supporting multiple webmanagers and containers
> seems to create a problem for applications that for one reason or
> another need to interact with the container but not necessarily with all
> of the containers.  Right now our interfaces provide the mechanism to
> return all web managers and all web containers for that manager.  The
> hosting webmanager and container are in there somewhere .... if I only
> knew it's name.  I think we need to provide some mechanism to either
> obtain the name of the hosting container/manager or actual references to
> these objects.  Is this information being tucked away somewhere as an
> attribute on the session?

If it is I'm not aware of it, but I think the deployer could register
a dependency with the dependency manager (WebModule A depends on
TomcatContainer B, for example).

Aaron

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