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JDBC API Modifications
JDBC API Modifications
The standard Java Database Connectivity (JDBC) API is used by BES to access
databases that support JDBC through vendor provided drivers. Requests for access to
a database is centralized through the BES JDBC Connection Pool. This section
describes modifications the BES JDBC pool makes to JDBC behavior for transactions.
The JDBC pool is a pseudo JDBC driver that allows a transactional application to
obtain a JDBC connection to a database. The JDBC pool associates JDBC
connections with the Transaction Manager's transactions, and delegates connection
requests to JDBC drivers that factory the JDBC connections. Once a connection is
obtained using the JDBC pool, the transaction is coordinated automatically by the
transaction service.
The JDBC pool and its associated resources provide complete transactional access to
the DBMS. The JDBC pool registers resources transparently with the transaction
coordinator. Because of limitations of the 1.x version of the JDBC API, the JDBC pool
can only provide one-phase commit. Version 2.0 of the JDBC API supports full twophase
commit.
Modifications to the behavior of the JDBC API
Note
To enable JDBC access for transactional applications written in Java, you use the
JDBC API. The JDBC API is fully documented at the following web site:
http://www.javasoft.com/products/jdk/1.2/docs/guide/jdbc/spec/jdbc-spec.frame.html
However, the behavior of some JDBC methods is overridden by the partition's
transaction service when they are invoked within the context of a transaction managed
by the partition. The following methods are affected:
■
Java.sql.Connection.commit()
■
Java.sql.Connection.rollback()
■
Java.sql.Connection.close()
■
Java.sql.setAutoCommit(boolean)
The rest of this section explains the changes to the semantics of these methods for
partition-managed transactions.
If a thread is not associated with a transaction, all of these methods will use the
standard JDBC transaction semantics.
Overridden JDBC methods
Java.sql.Connection.commit()
As defined in the JDBC API, this method commits all work that was performed on a
JDBC connection since the previous commit() or rollback(), and releases all database
locks.
If a global transaction is associated with the current thread of execution do not use this
method. If the global transaction is not a container-managed transaction, that is the
application manages its own transactions, and a commit is required use the JTA API to
perform the commit rather than invoking commit() directly on the JDBC connection.
Java.sql.Connection.rollback()
As defined in the JDBC API, this method rolls back all work that was performed on a
JDBC connection since the previous commit() or rollback(), and releases all database
locks.
178 BES Developer’s Guide