A Taxonomy of Qos- Aware, Adaptive Event- Dissemination Middleware Middleware Architecture the Core Related Work in Information Dissemination Security Load Balancing Reliability Fault Tolerance Ordering Del Semantics Adaptation Core Routing Scheme Event Model Overlay Routing Substrate Adaptive Event-dissemination Middleware

M iddleware for event broker networks (EBNs) both alleviates the issues related to underlying platform heterogeneity and provides a uniform application interface. A common service interface that such middleware provides is publish–subscribe,1 a paradigm in which producers publish information and consumers subscribe to it. In EBNs, information of interest is encapsulated in events; on such networks, middleware stores and manages subscriptions as well as routes events. This model’s fully decoupled nature in terms of time, space, and synchronization1 makes it highly suitable for large-scale distributed applications. Middleware for event broker networks is also known as eventdissemination middleware (EDM). To disseminate events, an EBN overlay network2 uses a subset of the underlying existing physical network (an overlay link itself is virtual but could consist of several physical links to the underlying network). Therefore, middleware must execute on each overlay node that has to work cooperatively to accomplish its functions. Such event-based architectures appear in various domains, many of which themselves require quality-of-service (QoS) guarantees from the underlying infrastructure. However, our survey of existing efforts in research-and-industrybased event dissemination middleware