Hi Dain,
thanks a lot for this input. Can you please resend your message to the
commons-dev list located at [email protected] ?
To add some a little bit confusion: The commons have just decided to
become a top-level project in their own right, so the development list
will move to [EMAIL PROTECTED] at some point in the near future.
Still, it would be great to follow up on your suggestions;
TransactionSupport would be a real benefit to DBCP.
Best regards
Henning
On Tue, 2007-07-03 at 18:21 -0700, Dain Sundstrom wrote:
> I just posted a patch JIRA which adds support for container managed
> connections to DBCP. In an environment where you have an accessible
> transaction manger such as Tomcat (when installed), Geronimo or
> OpenEJB, this patch allows adds support for pooling managed
> connections to an XA or non-XA data base.
>
> There are many libraries that use DBCP for non-managed environments,
> but when additional resources such as a JMS provider are added to the
> mix, they have to replace DBCP with something else. If you search
> google for XA and DBCP, you will loads of painful direction on how to
> replace DBCP with something else. I personally want to use DBCP in
> Tomcat with ActiveMQ.
>
> Anyways, enough with motivation....
>
> To use the new code, you need access to a TranactionManager (this
> code just creates a new Geronimo one).
>
> transactionManager = new TransactionManagerImpl();
>
> Then you either create an XADataSource and
> DataSourceXAConectionFactory or as this code does, create a normal
> DBCP ConnectionFactory and wrap it with a LocalXAConectionFactory
>
> Properties properties = new Properties();
> properties.setProperty("user", "username");
> properties.setProperty("password", "password");
> ConnectionFactory connectionFactory = new
> DriverConnectionFactory(
> new TesterDriver(),
> "jdbc:apache:commons:testdriver", properties);
>
> // wrap it with a LocalXAConnectionFactory
> XAConnectionFactory xaConnectionFactory = new
> LocalXAConnectionFactory(
> transactionManager,
> connectionFactory);
>
>
> Now you create a pool as normal (full reuse here).
>
> pool = new GenericObjectPool();
> pool.setMaxActive(getMaxActive());
> pool.setMaxWait(getMaxWait());
>
> // create the pool object factory
> PoolableConnectionFactory factory = new
> PoolableConnectionFactory(
> xaConnectionFactory,
> pool,
> null,
> "SELECT DUMMY FROM DUAL",
> true,
> true);
> pool.setFactory(factory);
>
>
> Finally, you create a special ManagedDataSource using the pool above
> and the special TransactionRegistry object obtained from the
> XAConnectionFactory.
>
> ds = new ManagedDataSource(pool,
> xaConnectionFactory.getTransactionRegistry());
> ds.setAccessToUnderlyingConnectionAllowed(true);
>
>
> That's it. The data source and connections work as normal until you
> start a transaction using the TransactionManager. When you use a
> connection while the transaction is active, the connection is
> enlisted in the transaction. When the transaction is complete, the
> connection is committed (or rolledback) and the connection returns to
> normal.
>
> Most of the new code extends existing classes or uses existing
> classes without modification. The key to this reuse is the
> TransactionRegistry abstraction which maintains a map from the
> Connection to the XAResource for that connection. The XAResource is
> needed to enlist a connection in a transaction. The
> TransactionRegistry and associated TransationContext class
> encapsulate all interactions with the TransactionManager leaving the
> Connection implementation relatively simple (making reuse easier).
>
> For now the code is contained in the org.apache.commons.dbcp.managed
> package, but I would suspect we may want to spread it out amongst the
> existing packages instead of creating a feature specific package.
> I'm also not sure what additional interfaces people may want such as
> equivalents of the BasicDataSource or BasicDataSourceFactory.
>
> The code has tests and has javadoc, but it needs real world testing
> and some real docs. I'm going try hooking it into OpenEJB and
> running it's massive test suite with a couple of opensource DBs.
>
> Anyways, I hope you all like it and accept the patch. I'm around to
> help with changes or whatever. I also ran into a few bugs while
> working on this that are already reported in JIRA (like the close
> bugs) and am willing to help with those also.
>
> -dain
>
>
>
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