3. Override method WBIManagedConnection.getLocalTransaction() and, if XA
support is provided, method WBIManagedConnection.getXAResource().
Wrap either or both of the LocalTransaction or XAResource instances returned by
these methods with a WBILocalTransactionWrapper or
WBIXATransacxtionWrapper instance, respectively. These wrappers provide
extended diagnostics for troubleshooting and also help adapters determine
whether or not to autocommit requests. According to the JCA 1.5 specification, a
resource adapter must autocommit transactions when being used outside the
context of a transaction. To help the managed connection determine if it is
involved in a transaction, these wrappers act as thin delegation layers, monitoring
the sequence of calls to determine whether a transaction is active. At the beginning
of a transaction, the wrappers call method setEnlistedInATransaction(true) on the
WBIManagedConnection instance; upon commit or rollback, the wrappers set this
same property to false. By then checking the status of the transaction via method
isEnlistedInTransaction on the super class, a WBIResourceAdapter subclass can
quickly determine whether it should be automatically committing transactions or
not when modifying the EIS.
Note: When overriding methods, do not invoke the super implementations of
these methods since the Adapter Foundation Classes simply throw exceptions for
these methods.
Example of an XA-enabled adapter implementation of
WBIManagedConnection
public class FooManagedConnection extends WBIManagedConnection
{
// just get the XAResource from your EIS and return the wrapper
public XAResource getXAResource() {
XAResource eisXAResource = this.eisXAConnection.getXAResource();
XAResource wrapper = new WBIXATransactionWrapper(eisXAResource,this);
return wrapper;
}
// here's an example of a potentially transacted call on the EIS. Point
// is that adapter should always check whether it's enlisted in a
// container-managed transaction or whether it should handle transaction
// on its own
private void updateRecord(int id,int value) {
if(!this.isEnlistedInTransaction())
this.eisConnection.beginTransaction();
eisConnection.updateRecord(id,value);
if(!this.isEnlistedInTransaction())
this.eisConnection.commitTransaction();
}
}
Using command patterns
Command patterns simplify adapter development by providing generic logic for
dealing with hierarchical data structures.
Command patterns:
To enhance uniformity across adapters for outbound processing, support for
command patterns is provided by the CommandManager API in the Adapter
Foundation Classes.
WebSphere Adapter development overview 105
