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From Mike Starkie <skij...@yahoo.com>
Subject Re: GenericKeyedObjectPoolFactory - failover question
Date Sun, 13 Mar 2005 19:59:40 GMT
this makes sense now.  thank you.

If I want to create a system where my java code can
failover to a redundant database on connection errors
do I need to set up two distinct PoolingDataSources
and  
logically switch between them when an connection error
occurs or is there some built in classes which handle
failovers of this type?


--- Vikram Goyal <tech@craftbits.com> wrote:

> Hi Mike,
> 
> Yes, it can seem very confusing to use these
> libraries.
> 
> The best way for me to explain it would be with some
> code snippet.
> 
> // create your connection pool
> GenericObjectPool pool = new GenericObjectPool();
> 
> // and set its properties
> // ..
> 
> // then your connection factory
> ConnectionFactory cf = new
> DriverManagerConnectionFactory(.....);
> 
> // then a factory for your prepared statements
> KeyedObjectPoolFactory kpf = new
> GenericKeyedObjectPoolFactory(null, 8);
> 
> // finally, your overall connection factory
> PoolableConnectionFactory pcf = new
> PoolableConnectionFactory(cf, pool, kpf, 
> null, false, true);
> 
> This poolable connection factory will now be set to
> pool connections and 
> prepared statements around those connections. The
> key here is to understand 
> that in this case, you don't use the
> PoolingConnection class directly, but 
> let the PoolableConnectionFactory to manage it
> internally (It uses 
> PoolingConnection internally to pool prepared
> statements around connections, 
> using the kpf; so you don't need to match
> connections with statements and so 
> on). I perhaps misled you initially when I said that
> you can use 
> PoolingConnection, but at that point I did not know
> your exact requirements.
> 
> I hope this clears it up more.
> 
> Vikram
>
---------------------------------------------------------------------------------------
> Jakarta Commons Online Bookshelf
> Module 9: Pool and DBCP:
> http://www.manning.com/catalog/view.php?book=goyal9
> All Modules: http://www.manning.com/goyal
>
---------------------------------------------------------------------------------------
> 
> ----- Original Message ----- 
> From: "Mike Starbuck" <skijore@yahoo.com>
> To: "Jakarta Commons Users List"
> <commons-user@jakarta.apache.org>
> Sent: Sunday, March 13, 2005 8:09 AM
> Subject: Re: GenericKeyedObjectPoolFactory
> 
> 
> > Vikram,
> > I'm confused. I want to create a pool of
> connections
> > and for each connection, pool the statements used
> on
> > the connection.
> >
> > The problem is the PoolableConnectionFactory will
> only
> > create a PoolingConnection if it was initialized
> with
> > an implementation of keyedObjectPoolFactory
> otherwise
> > it will just return the connection created by the
> > ConnectionFactory it was initialized with. In my
> case
> > that is a DriverManagerConnectionFactory.
> >
> > The most basic implementation of
> > keyedObjectPoolFactory is
> > GenericKeyedObjectPoolFactory which requires an
> > instance of KeyedPoolableObjectFactory.  There are
> no
> > concrete implementations of
> KeyedPoolableObjectFactory
> > in commons-pool and the only other suitable
> > implementation seems to be PoolingConnection in
> > commons-dbcp.  But that implementation requires a
> > Connection in order to initialize!
> >
> > It seems to me like a chicken and egg problem:  In
> > order to create the factory to make connections
> that
> > pool statements I need to specify the factory that
> I
> > want to pool the statements but the only
> > implementation available requires a connection.
> >
> > This is my second day with this package so please
> feel
> > free to fill me in on the right way to set this
> up.
> >
> > thank you,
> >
> >
> > --- Vikram Goyal <tech@craftbits.com> wrote:
> >> Hi Mike,
> >>
> >> You need to use the PoolingConnection class. It
> >> implements
> >> KeyedPoolableObjectFactory. For some reason, the
> >> Javadocs for
> >> KeyedPoolableObjectFactory don't reflect this.
> >>
> >> HTH,
> >> Vikram
> >>
> >>
> >
>
---------------------------------------------------------------------------------------
> >> Jakarta Commons Online Bookshelf
> >> Module 9: Pool and DBCP:
> >>
> http://www.manning.com/catalog/view.php?book=goyal9
> >> All Modules: http://www.manning.com/goyal
> >>
> >
>
---------------------------------------------------------------------------------------
> >>
> >> ----- Original Message ----- 
> >> From: "Mike Starbuck" <skijore@yahoo.com>
> >> To: <commons-user@jakarta.apache.org>
> >> Sent: Saturday, March 12, 2005 9:08 AM
> >> Subject: GenericKeyedObjectPoolFactory
> >>
> >>
> >> > Is there a way to create an instance of
> >> > GenericKeyedObjectPoolFactory using an
> >> implementation
> >> > of BasekeyedPoolableObjectFactory.   I can't
> find
> >> a
> >> > concrete  class that impelments
> >> > KeyedPoolableObjectFactory in the
> commons-pool-1.2
> >> package.
> >> >
> >> > -- 
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