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1.3.11 Unicast vs. Multicast Messages

SRMP messages can be sent to either a single destination queue (called a unicast message) or simultaneously to multiple destination queues (called a multicast message). If unicast messaging is used, the underlying transport protocol is HTTP 1.1. If multicast messaging is used, the underlying transport protocol is PGM [RFC3208]. The only visible difference in the protocol message is the format name of the destination queue:

  • If the message is sent to a single destination queue as a unicast message, the destination queue name is stated as a Uniform Resource Identifier (URI) that uses HTTP as follows.

     <to>http://destinationhost/msmq/private$/simpleq</to>
    
  • If the message is sent to multiple destination queues as a multicast message, the destination queue name is stated as a multicast URI that uses the PGM Protocol as follows.

     <to>MSMQ:MULTICAST=234.1.1.1:8001</to>