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From "Tauzell, Dave" <Dave.Tauz...@RxHub.net>
Subject RE: [DBCP] Connections Die
Date Fri, 07 Mar 2003 18:59:16 GMT
Weblogic's JDBC pool has two options:

1. Validate on checkout
2. Validation on return

You can select any or none of the options.  If you don't select any and
the pooled connections go bad, then you'll get bad connections when
checking out. I personally like validating the connection on checkout,
although your code is then tied to a pool that does this.

-Dave

-----Original Message-----
From: Stephen Westbom [mailto:swestbom@yahoo.com] 
Sent: Friday, March 07, 2003 11:52 AM
To: Jakarta Commons Users List
Subject: RE: [DBCP] Connections Die


I think that DBCP needs to be aware of the type of JDBC implementation
classes it is dealing with and pick the correct implementation wrappers
for each JDBC implementation.  Only use the generic wrappers for oddball
drivers.

It is more development work for DBCP but would allow for proper
encapsulation. 
The commercial products generally do this.

I don't think it is necessarily a good idea to catch it on checkout with
a validation query and return a new connection seamlessly.  I think that
is really right on the line for application versus framework code.

Thanks
Stephen

--- "McKinstry, Pete (HQP)" <Pete.McKinstry@rhi.com> wrote:
> For validation queries, it quietly kills the connection & attempts to 
> use a different one from the pool (or re-create if necessary). Thereby

> getting the desired behavior.
> 
> In the context of normal connection usage, how would it know what a 
> fatal error is? Each database is different, and SQLExceptions aren't 
> necessarily fatal. That's the trick.
> 
> -pgm
> 
> -----Original Message-----
> From: Stephen Westbom [mailto:swestbom@yahoo.com]
> Sent: Friday, March 07, 2003 8:53 AM
> To: Jakarta Commons Users List; 'Evelynn'
> Subject: RE: [DBCP] Connections Die
> 
> 
> The pool should really kill the connection itself (with or without a 
> validation
> query) when it gets a fatal connection error.  It should then throw an

> error to the application.
> 
> 
> --- "McKinstry, Pete (HQP)" <Pete.McKinstry@rhi.com> wrote:
> > Evelynn-
> > 
> > Have you tried specifying a validation query in your DBCP config? I
> believe
> > it destroys connections in the pool where the validationQuery throws

> > a SQLException. This may solve your problem w/o having to close & 
> > re-create the DataSource.
> > 
> > See: http://jakarta.apache.org/commons/dbcp/apidocs/index.html
> > BasicDataSource
> > 	- validationQuery
> > 	- testOnReturn
> > 	- testWhileIdle
> > 	- testOnBorrow
> > 
> > fyi- I haven't used DBCP from w/in Tomcat, so i'm not sure how to
> configure
> > there, but it should be do-able...
> > 
> > -pgm
> > 
> > -----Original Message-----
> > From: Evelynn [mailto:evelynnuser1@earthlink.net]
> > Sent: Thursday, March 06, 2003 5:31 PM
> > To: commons-user@jakarta.apache.org
> > Subject: [DBCP] Connections Die
> > 
> > 
> > Reference: Tomcat 4.1.18
> > My dbcp goes dead at times.
> > My application on Tomcat is on one box and my DB2 database is on 
> > another box.  If the network goes down for a brief period or the 
> > database is bounced, my dbcp no longer works and I receive an 
> > SQLException from my application running on Tomcat.
> > 
> > So, here is my fix to refresh the connection pool.  When ever I 
> > receive an SQLException, I run the following once:
> > 
> > import javax.sql.DataSource;
> > import org.apache.commons.dbcp.BasicDataSource;
> > .......
> > BasicDataSource bds = (BasicDataSource)myDataSource; bds.close();
> > 
> > I tested this and it seems to solve the problem.    The only thing
that I
> do
> > not like about this solution is that the java code in my app now 
> > includes
> a
> > reference to the DBCP java class.  But that's OK.  I can live with 
> > that. My question is, is this solution OK or is there a better 
> > recommendation to refresh the dbcp?
> > 
> > Thanks
> > Eve
> > 
> > 
> > 
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> > 
> 
> 
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