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Date: Fri, 9 Mar 2001 12:28:59 -0800 (PST)
From: cmanolache@yahoo.com
To: tomcat-dev@jakarta.apache.org
Subject: RE: where to plug-in startup/shutdown knowledge for internal tomcat
 components
In-Reply-To: <OJEAJPBEJCDMCKNGPDDBAEAGCAAA.clucas@armassolutions.com>
Message-ID: <Pine.LNX.4.21.0103091219370.1630-100000@simona.wyn.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Fri, 9 Mar 2001, Casey Lucas wrote:

> So, given all that, I need to control lifetime of TagHandlerPoolManager's
> default instance.  By controlling it, I can have one TagHandlerPoolManager
> instance per web application and when the web application gets unloaded,
> all the Tag.release methods can be called.  Aren't the JspServlet and
> JspInterceptor mechanisms specific to an individual jsp file?  If so,
> I don't think that's what I need because pooling will be for the entire
> web application not a specific JSP.

> I was hoping that when the web application (not individual jsp) is
> loaded, unloaded, reloaded I could do the TagHandlerPoolManager initialization
> and cleanup tasks.  Maybe I'm making things too complicated.  Should
> managing the lifetime of a per-web-application object like
> TagHandlerPoolManager be simpler?

And you have 2 solutions:
1. Use tomcat hooks. You can let a tomcat module manager the
TagHandlerPool and you'll get all the notifications you need. 
Just implement and TagPoolManagerInterceptor module, implement
the hooks you need ( addContext, contextInit, reload, etc).

2. Use some "hacks" in the generated init()/destroy().
For example, in init() you can use a context attribute ( TagPoolManager ),
if not set you'll create it and init, if it's set you just use it. 

> Am I off base, with my general strategy?

No, it is ok.
 
> Also, regarding 3.x and 4.x, I'd like to keep it usable / adaptable
> to all.  We're currently using 3, but will eventually migrate to 4.

4.x also have a mechanism to notify you about events - either a 2.3 filter
or use the internal Listener interfaces, and most decent servlet
containers will provide such a mechanism.

As long as you keep a simple interface to your tag pool, it should be easy
to write the container-specific adapter that will plug it in.


Costin


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