Messaging systems based on queuing include products such as Microsoft’s MSMQ [28]and IBM’s MQSeries [29]. The queuing model with their store-and-forward mechanisms come into play where the sender of the message expects someone to handle the message while imposing asynchronous communication and guaranteed delivery constraints. A widely used standard in messaging is the Message Passing Interface Standard (MPI) [21]. MPI is designed for high performance on both massively parallel machines and workstation clusters. Messaging systems based on the classical remote procedure calls include CORBA [35], Java RMI [32] and DCOM [19]. In publish/subscribe systems the routing of messages from the publisher to the subscriber is within the purview.
