Maintaining QoS for Publish/Subscribe Middleware in Dynamic Environments

The number and type of distributed systems that utilize publish/subscribe (pub/sub) technologies are growing due to the advantages of performance, cost, and scale compared with single computers. Examples of pub/sub middleware include Web Services Brokered Notification, the Java Message Service (JMS), the CORBA Event Service, and the Data Distribution Service (DDS). These technologies support data propagation throughout a system using an anonymous subscription model that decouples event suppliers and consumers. Pub/sub middleware is used in many application domains, ranging from shipboard computing environments to fractionated spacecraft constellations. The middleware supports policies that affect the end-to-end QoS of the system.