Structured Wide-Area Programming

Internet today provides a wide range of services associated with web sites; examples include getting a stock quote, making an airline reservation, compressing a file or inverting a matrix. Each service may be likened to a basic operation in a computer, the internet computer. An application is a program written over the basic services, i.e., an orchestration of the services. This research is directed toward designing, implementing and studying an appropriate model of orchestration that would allow us to develop wide-area applications succinctly. Just as structured programming gave programmers effective tools to organize the control flow of sequential programs, our research introduces mechanisms to organize the communication, synchronization and coordination in programs that run on wide-area networks. We have developed a programming model, called Orc, for structured wide-area programming. Orc includes constructs to orchestrate the concurrent invocation of services to achieve a goal -- while managing time-outs, priorities, and failure of sites or communication.  The talk will give an introduction to Orc, and some of the ongoing research on enhancing the model. The Orc web page is at http://orc.csres.utexas.edu