One of the many points I raised earlier was how to properly close a database connection, and how that might change depending on whether you were using connection pooling and/or a DataSource. The example JDBC code cited was that in the Struts 1.0.2 Javadoc:
http://jakarta.apache.org/struts/doc-1.0.2/api/org/apache/struts/util/package-summary.html#doc.JDBC The part that looked a little funny to me and others was the call to [myConnection].rollback() in the catch{} block. I think I finally figured out why this was put in - defensive programming. It seems to me that if *any* part of a transaction is successful, then [connection].rollback() needs to be called, else the next piece of application code that got its hands on that connection object and completed a transaction successfully would also complete the previously-uncommitted transaction. For example, let's say your updateDB() method has two separate method calls made within it that each update a table. If only the first conn.executeUpdate() method completes successfully, and the second conn.executeUpdate() throws some kind of SQLException, that transaction will *not* automatically be rolled back. The driver won't do it. The database would do it only when the connection is finally closed. But what if that connection is part of a connection pool, and before the application server (and thus the pool) goes down for the night, that updateDB() method is used again, this time with success. Now, the leftover transaction from the first failed call to updateDB() has been committed along w/ any changes from follow-on calls to updateDB(). All of this happens, if your DataSource/Connection Pooling Mechanism/Wrapped Connection Object isn't smart enough to call [connection].rollback() for you. The GenericConnection object that ships with Struts is smart enough - and that's why I probably hadn't been burned in the past while using Struts, and not calling conn.rollback() myself. The GenericConnection object's first task in its close() method is to call connection.rollback(). So, as long as I call connection.close() before leaving my updateDB() method, I'm good to go. /* Code snippet from Struts source */ ... // Clean up any outstanding transaction as best we can try { conn.rollback(); } catch (SQLException e) {} ... Hope all this is correct...don't want to mislead people... __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com -- To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>
