MOM --- MOM is Asynchronous Middleware - it allows a sender to submit a message to delivery without waiting to reply from the receiver - in other words it is using a non blocking mechanism. MOM is very popular Middleware whenever you need to do cross domain communication in which down time is inevitable and messages needed to be queued for future delivery. CORBA on the other hand (with the exception of the Event Channel) is using a blocking mechanism. A sender is blocked till the receiver accepts the message. A MOM sender submits a message into a message queue. The message can then either be pulled or pushed out from the queue to the receiver. The important thing to remember is that the sender can continue processing regardless of the message delivery status. This can also create some issues with message synchronization and sequencing for multiple messages belonging to the same logical transaction. Some other very important differences are that CORBA is coming with a rich framework of services such as IDL, Naming, Transaction, Security, etc. MOM on the other hand deals primarily with guaranteed message delivery and message translation services. Both ORB and MOM are essential Middleware types. The separation between the two of them will most likely disappear when Middleware vendors will offer a combination of both (IONA, BEA Systems). As a generalization, ORBs are more likely to be used when immediate response time is required and you can allow using a blocking mechanism. MOM is more likely to be used when you need to integrate with Legacy systems and you anticipate a need to queue transaction due to downtime of part of the system. The great thing about queued transactions is that you can present the client a 24 by 7 operation while in the back office you can still bring systems down for maintenance. CORBA ----- The existing CORBA programming model is synchronous. OMG is working on an asynchronous mode. In CORBA, you are programming to the server object's proxy. My point here is that CORBA allows the programmer to think in OO terms in spite of the ditributed nature whereas MOM forces you to think about the distributed nature and totally obscures the OO-ness.
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- To: <xmlblaster at server.xmlBlaster.org>
- Subject: CORBA Messaging
- From: "zxm" <xiaomz at nudt.edu.cn>
- Date: Tue, 4 Jan 2000 22:16:19 +0800
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