The difference between the two types of remote queue definitions is described in the WebSphere MQ Everyplace Application Programming Guide. To summarize:
Figure 31 shows an example of a remote queue set up for synchronous operation and a remote queue setup for asynchronous operation.
In both the synchronous and asynchronous examples queue manager qm2 has a local queue invQ.
In the synchronous example, queue manager qm1 has a remote queue definition of queue invQ. invQ resides on queue manager qm2. The mode of operation is set to synchronous.
An application using queue manager qm1 and putting messages to queue qm2.invQ establishes a network connection to queue manager qm2, if it does not already exist, and the message is immediately put on the real queue. If the network connection cannot be established then the application receives an exception that it must handle.
In the asynchronous example, queue manager qm1 has a remote queue definition of queue invQ. invQ resides on queue manager qm2. The mode of operation is set to asynchronous.
An application using queue manager qm1 and putting messages to queue qm2.invQ stores messages temporarily on the remote queue on qm1. When the transmission rules allow, the message is moved to the real queue on queue manager qm2. The message remains on the remote queue until the transmission is successful.
To set a queue for synchronous operation, set the Queue_Mode field to Queue_Synchronous.
Asynchronous queues require a message store to temporarily store messages. Definition of this message store is the same as for local queues.
To set a queue for asynchronous operation, set the Queue_Mode field to Queue_Asynchronous.
The following code fragment shows how to setup an administration message to create a remote queue.
/** * Create a remote queue */ protected void createQueue(MQeQueueManager localQM, String targetQMgr, String qMgrName, String queueName, String description, String queueStore, byte queueMode ) throws Exception { /* * Create an empty queue admin message and parameters field */ MQeRemoteQueueAdminMsg msg = new MQeRemoteQueueAdminMsg(); MQeFields parms = new MQeFields(); /* * Prime message with who to reply to and a unique identifier */ MQeFields msgTest = primeAdminMsg( msg ); /* * Set name of queue to manage */ msg.setName( qMgrName, queueName ); /* * Add any characteristics of queue here, otherwise * charateristics will be left to default values. / if ( description != null ) // set the description ? parms.putUnicode( MQeQueueAdminMsg.Queue_Description, description); // set the queue access mode if mode is valid if ( queueStore != MQeQueueAdminMsg.Queue_Asynchronous && queueStore != MQeQueueAdminMsg.Queue_Synchronous ) throw new Exception ("Invalid queue store"); parms.putByte( MQeQueueAdminMsg.Queue_Mode, queueMode); if ( queueStore != null ) // Set the queue store ? // If queue store includes directory and file info then it // must be set to the correct style for the system that the // queue will reside on e.g \ or / parms.putAscii( MQeQueueAdminMsg.Queue_FileDesc, queueStore ); /* * Other queue characteristics like queue depth, message expiry * can be set here ... */ /* * Set the admin action to create a new queue */ msg.create( parms ); /* * Put the admin message to the admin queue (not assured delivery) * on the target queue manager */ localQM.putMessage( targetQMgr, MQe.Admin_Queue_Name, msg, null, 0); }
For synchronous operation, the queue characteristics for inclusion in the remote queue definition can be obtained using queue discovery.