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minimized by using XML routers and highly expressive subscription semantics expressed through XPath* or XQuery. Topic-based publish/subscribe systems have made use of IP multicast to transport traffic between content-based routers by mapping predefined topics into IP multicast groups. While efficient for use in topic-or subject-based implementations, using IP multicast for XML message transport is not scalable. In XML publish/subscribe systems, constraints are not restricted to a limited part of the document, but instead any part/tag of the document is a valid target which would require a near-infinite number of IP multicast groups and dynamic mapping between groups and subscriptions.The communication network between the publishers (producers) and subscribers (consumers) is responsible for filtering and routing the messages to the appropriate destinations. This communication network infrastructure typically consists of applicationlevel routers communicating in an overlay network IntroductionExtensible markup language (XML) [9] is the de facto standard for interapplication data representation. Geer [5] suggests XML traffic will grow to 40 percent of Internet traffic in 2008. XML is used in many diverse communication models, including Web services [10]. Use in wide area network (WAN)-scale publish/subscribe paradigms has also garnered interest. Our work focuses on content-based networking and XML publish/subscribe where messages are routed from source to destination on the basis of message content instead of sender-defined destination Internet Protocol (IP) addresses. This allows recipients to select what they want to receive by registering their interests with the network. The expressiveness of these interest expressions determines the amount of traffic received and impacts solution effectiveness and efficiency. For example, in a topic-based system, a recipient has no option but to receive all published data produced under a specific predefined topic or subject [6]. The amount of traffic received can be N Scalable XML Routed Network Topology Generation Khurram Masood, Ashraf Matrawy, Bashar Bou-Diab, and