O'Reilly - Java Message Service

}
return;
session.commit();
}
else if ( rollbackOnly ){
inRollback = true;
session.rollback( );
}
else
session.commit( );
}
if ( rollbackOnly )
return; // Ignore all other messages while in rollback mode
...
// If price reduction is greater than 10 percent, buy
if (newPrice == 0 || oldPrice / newPrice > 1.1){
System.out.println ("\nBuying " + count + " " + itemDesc);
...
publisher.publish(
buyTopic,
textMsg,
javax.jms.DeliveryMode.PERSISTENT,
javax.jms.Message.DEFAULT_PRIORITY,
1800000);
} else {
System.out.println ("\nBad Deal. Not buying");
rollbackOnly = true;
}
First we will examine what makes the rollback happen:
// If price reduction is greater than 10 percent, buy
if (newPrice == 0 || oldPrice / newPrice > 1.1){
...
} else {
System.out.println ("\nBad Deal. Not buying");
rollbackOnly = true;
}
Java Message Service
The rollbackOnly variable is a boolean used by the application to signal that a rollback
needs to occur. If you are familiar with the EJB transaction model, this is similar to calling
the setRollbackOnly( ) method on an EJB entity bean. The messages in the transaction are
either all commited, or they are all rolled back. Setting the rollback-only flag indicates a
deferred rollback. The processing of any message in the group can set the rollbackOnly
flag. Since the "Buy Order" messages are all part of the same transaction, they will be
retained by the JMS provider and will go no further. When the "END_SEQUENCE" message
arrives, the rollbackOnly flag is examined:
if ( sequence.equalsIgnoreCase("END_SEQUENCE") )
{
if ( redelivered && inRollback ){ // at the end, start fresh
inRollback = false;
rollbackOnly = false;
session.commit();
}
else if ( rollbackOnly ){
inRollback = true;
session.rollback( );
}
else
session.commit( );
}
return;
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