org.enhydra.jdbc.standard

Class StandardXAConnection

java.lang.Object

org.enhydra.jdbc.standard.StandardPooledConnection

org.enhydra.jdbc.standard.StandardXAConnection

All Implemented Interfaces:

Runnable, Referenceable, PooledConnection, XAConnection, XAResource

Direct Known Subclasses:

IdbXAConnection, InformixXAConnection, OracleXAConnection, SybaseXAConnection

public class StandardXAConnection
extends StandardPooledConnection
implements XAConnection, XAResource, Referenceable, Runnable

Provides a generic wrapper for JDBC 1 drivers. JDBC 1 drivers always associate a single transaction at every point in time with a physical connection. J2EE drivers, on the other hand, allow an XAResource (and therefore an XAConnection with which it has a one to one mapping) to switch between global transactions.

To accomodate this, the StandardXADataSource class maintains a list of Connection objects. When the Transaction Manager associates an XID with a StandardXAConnection, it looks for a physical connection which is associated with that transaction.

The "current" connection (super.con and curCon) is the connection currently being used by the application (i.e. getConnection has been called, but not Connection.close()). The current connection is removed and handed to the data source if it becomes associated with a global transaction.

Field Summary

Fields

Modifier and Type	Field and Description
StandardXAConnectionHandle	connectionHandle
protected StandardXAStatefulConnection	curCon
boolean	thisAutoCommit
Thread	timerThread
TransactionManager	transactionManager
protected StandardXADataSource	xaDataSource

Fields inherited from class org.enhydra.jdbc.standard.StandardPooledConnection

con, dataSource, log

Fields inherited from interface javax.transaction.xa.XAResource

TMENDRSCAN, TMFAIL, TMJOIN, TMNOFLAGS, TMONEPHASE, TMRESUME, TMSTARTRSCAN, TMSUCCESS, TMSUSPEND, XA_OK, XA_RDONLY

Constructor Summary

Constructors

Constructor and Description
StandardXAConnection(StandardXADataSource dataSource, String user, String password) Creates the first free connection.

Method Summary

Modifier and Type	Method and Description
StandardXAStatefulConnection	checkPreparedState(Xid xid) Does most of the work of a generic prepare.
void	close() Close this XA connection.
void	commit(Xid xid, boolean onePhase) Performs a commit on this resource manager's branch of the global transaction.
void	doStart(Xid xid, int flags) Does most of the work of the start() call (below).
void	end(Xid xid, int flags) Ends a connection's association with a global transaction.
void	forget(Xid xid) This is called by a TM when the RM has reported a heuristic completion.
boolean	getCommitOnPrepare()
Connection	getConnection() Creates a new StandardXAConnectionHandle for use by an application.
Reference	getReference()
int	getTransactionTimeout()
XAResource	getXAResource() We are required to maintain a 1-1 mapping between an XAConnection and its corresponding XAResource.
boolean	isSameRM(XAResource xares)
protected void	newConnectionHandle()
int	prepare(Xid xid) Prepares to perform a commit.
Xid[]	recover(int flag) Called by the transaction manager during recovery.
void	rollback(Xid xid) PERFORMS a rollback on this resource manager's branch of the global transaction.
void	run() Periodically checks for timed out connections.
void	setCommitOnPrepare(boolean commitOnPrepare)
void	setTransactionManager(TransactionManager tm)
boolean	setTransactionTimeout(int seconds) Accessor methods for timeout.
void	start(Xid xid, int flags) Associates this XAConnection with a global transaction.
String	toString()

Methods inherited from class org.enhydra.jdbc.standard.StandardPooledConnection

addConnectionEventListener, addStatementEventListener, connectionErrorOccurred, getPhysicalConnection, removeConnectionEventListener, removeStatementEventListener, setLogger

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface javax.sql.PooledConnection

addConnectionEventListener, addStatementEventListener, removeConnectionEventListener, removeStatementEventListener

Field Detail

curCon

protected StandardXAStatefulConnection curCon

timerThread

public Thread timerThread

transactionManager

public TransactionManager transactionManager

connectionHandle

public StandardXAConnectionHandle connectionHandle

xaDataSource

protected StandardXADataSource xaDataSource

thisAutoCommit

public boolean thisAutoCommit

Constructor Detail

StandardXAConnection

public StandardXAConnection(StandardXADataSource dataSource,
                            String user,
                            String password)
                     throws SQLException

Creates the first free connection.

Throws:

SQLException

Method Detail

getXAResource

public XAResource getXAResource()

We are required to maintain a 1-1 mapping between an XAConnection and its corresponding XAResource. We achieve this by implementing both interfaces in the same class.

Specified by:

getXAResource in interface XAConnection

getConnection

public Connection getConnection()
                         throws SQLException

Creates a new StandardXAConnectionHandle for use by an application. If there is already an StandardXAConnectionHandle in use then it is closed (i.e. the application has the connection withdrawn).

This method always returns a Connection in the free state (i.e. (not associated with an Xid). This is necessary since, unless Start (Xid, flags) gets called, the Connection must do local transaction processing.

Specified by:

getConnection in interface PooledConnection

Overrides:

getConnection in class StandardPooledConnection

Throws:

SQLException

newConnectionHandle

protected void newConnectionHandle()

Overrides:

newConnectionHandle in class StandardPooledConnection

setTransactionManager

public void setTransactionManager(TransactionManager tm)

close

public void close()
           throws SQLException

Close this XA connection.

Specified by:

close in interface PooledConnection

Overrides:

close in class StandardPooledConnection

Throws:

SQLException

doStart

public void doStart(Xid xid,
                    int flags)
             throws XAException

Does most of the work of the start() call (below). Kept as a separate method so that subclasses can call it and retain the curCon property.

Throws:

XAException

start

public void start(Xid xid,
                  int flags)
           throws XAException

Associates this XAConnection with a global transaction. This is the only method which can associate the current connection with a global transaction. It acts only on the current connection which must have been previously established using getConnection.

Specified by:

start in interface XAResource

Throws:

XAException

end

public void end(Xid xid,
                int flags)
         throws XAException

Ends a connection's association with a global transaction.

It need not act on the current transaction. There is an interval between being returned to the pool manager and being invoked by the transaction manager during which the current connection can change.

Note that the only effect is to change the connection state.

Specified by:

end in interface XAResource

Throws:

XAException

checkPreparedState

public StandardXAStatefulConnection checkPreparedState(Xid xid)
                                                throws XAException

Does most of the work of a generic prepare. Kept as a separate method so that sub-classes can call it and get the StandardXAStatefulConnection back.

Throws:

XAException

prepare

public int prepare(Xid xid)
            throws XAException

Prepares to perform a commit. May actually perform a commit in the flag commitOnPrepare is set to true.

Specified by:

prepare in interface XAResource

Throws:

XAException

commit

public void commit(Xid xid,
                   boolean onePhase)
            throws XAException

Performs a commit on this resource manager's branch of the global transaction.

Specified by:

commit in interface XAResource

Throws:

XAException

rollback

public void rollback(Xid xid)
              throws XAException

PERFORMS a rollback on this resource manager's branch of the global transaction.

Specified by:

rollback in interface XAResource

Throws:

XAException

isSameRM

public boolean isSameRM(XAResource xares)
                 throws XAException

Specified by:

isSameRM in interface XAResource

Throws:

XAException

forget

public void forget(Xid xid)
            throws XAException

This is called by a TM when the RM has reported a heuristic completion. It must retain the transaction context until told to forget about it.

Specified by:

forget in interface XAResource

Throws:

XAException

recover

public Xid[] recover(int flag)
              throws XAException

Called by the transaction manager during recovery. If it was the transaction manager or another compoenent which failed then we can supply our known Xids. However if we failed then this method does nothing - we need to know about database internals to do that.

Specified by:

recover in interface XAResource

Throws:

XAException

setTransactionTimeout

public boolean setTransactionTimeout(int seconds)

Accessor methods for timeout.

Specified by:

setTransactionTimeout in interface XAResource

getTransactionTimeout

public int getTransactionTimeout()

Specified by:

getTransactionTimeout in interface XAResource

setCommitOnPrepare

public void setCommitOnPrepare(boolean commitOnPrepare)

getCommitOnPrepare

public boolean getCommitOnPrepare()

run

public void run()

Periodically checks for timed out connections.

Specified by:

run in interface Runnable

getReference

public Reference getReference()
                       throws NamingException

Specified by:

getReference in interface Referenceable

Throws:

NamingException

toString

public String toString()

Overrides:

toString in class StandardPooledConnection