The XStreamCast project addresses the efficient processing of XQueries over continuous streams in which a server broadcasts XML data to multiple clients concurrently and a client may tune-in to multiple streams at the same time. The goal of this project is to develop a framework that improves query throughput and response time on all clients, taking full advantage of their limited resources. Under this framework, the unit of transmission in an XML stream is an XML fragment, which corresponds to one or a few XML elements from the transmitted document. A server may choose to disseminate XML fragments from multiple documents in the same stream, can repeat some fragments when they are critical or in high demand, can replace them by sending delta changes, and can delete invalid ones. The client architecture is based on an optimization framework for XQuery that utilizes many efficient evaluation algorithms for processing XML data streams under memory and processing power constraints. The end goal is the construction of a complete prototype system based on the theoretical framework, which is expected to drastically improve performance when compared with other stream processing systems. The algorithms and the software resulting from this project will have a broader impact on a wide range of applications, especially in electronic commerce, since they will improve the way services are provided to clients. They will also reduce network traffic between servers and clients and will give the ability to small service providers and businesses to serve a larger number of clients using less powerful server computers and lower cost networking. The project Web site (http://lambda.uta.edu/XStreamCast/) will provide access research results and to a public interface to allow other researchers to test-drive the XQuery engine.
