> -----Original Message-----
> From: David Graham [mailto:[EMAIL PROTECTED]
> Sent: Friday, February 28, 2003 1:53 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [POOL] Pool listeners
>
>
> I would make PoolListener more closely match the Java
> listener style. That
> is:
> 1. PoolListener extends java.util.EventListener
Makes sense.
> 2. The methods accept an event object that extends
> java.util.EventObject (maybe call it PoolEvent).
Again, makes sense.
> 3. The methods shouldn't throw Exception. They should throw specific
> exception types or non at all.
I thought about declaring something like ListenerException to be thrown
instead. ListenerException would be a subclass of NestableException for
commons-lang. Would this be better?
Consider a pool of database connections. A listener is configured to
handle onBorrow(). The goal is to execute a stored procedure or
something before the connection is returned from the pool. There is the
possibility that a SQLException could be thrown during the execution.
Of course it would have to be trapped within the listener code and
rethrown as a ListenerException. This just give the person writing the
listener the option to either silently ignore the failure or to throw an
Exception.
> I like the concept.
>
> David
>
>
>
>
> >From: "Quinton McCombs" <[EMAIL PROTECTED]>
> >Reply-To: "Jakarta Commons Developers List"
> ><[EMAIL PROTECTED]>
> >To: <[EMAIL PROTECTED]>
> >Subject: [POOL] Pool listeners
> >Date: Fri, 28 Feb 2003 13:19:48 -0600
> >
> >I am working on a patch to allow listeners to be added to pools that
> >will receive notifications on various events. Does anyone object to
> >having this functionality included?
> >
> >Here is the design -
> >
> >I was thinking about adding support for a PoolListener interface for
> >the pool component. Object which implement this interface could be
> >added to any ObjectPool or KeyedObjectPool. The listener would be
> >notified on the following events:
> >
> >- An object is borrowed from the pool
> >- An object is returned to the pool
> >- An new object is created and added to the pool
> >- An object is removed from the pool
> >
> >addListener(PoolListener) would be defined in ObjectPool and
> >KeyedObjectPool. It would be implemented in BaseObjectPool and
> >BaseKeyedObjectPool. Also in the previous two Base*
> classes, protected
> >methods would be added to handle sending out the
> notifications to the
> >list of listeners.
> >
> >public interface PoolListener
> >{
> > /**
> > * Executed immediatedly before an object is returned
> from the pool.
> > *
> > * @param obj The object being returned
> > * @throws Exception generic exception
> > */
> > void onBorrow(Object obj) throws Exception;
> >
> > /**
> > * Executed immediately after an object is returned to the pool.
> > *
> > * @param obj the object being returned
> > * @throws Exception generic exception
> > */
> > void onReturn(Object obj) throws Exception;
> >
> > /**
> > * Executed immediately after a new object is created
> but before it
> > * is added to the pool.
> > *
> > * @param obj the newly created object
> > * @throws Exception generic exception
> > */
> > void onCreate(Object obj) throws Exception;
> >
> > /**
> > * Executed when an object is removed from the pool.
> > *
> > * @param obj The object being removed.
> > * @throws Exception generic exception
> > */
> > void onDestroy(Object obj) throws Exception;
> >
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>
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