Using reliable multicast for caching and collaboration within the world wide web

The World Wide Web has become an important medium for information dissemination. One model for synchronized information dissemination within the Web is webcasting in which data are simultaneously distributed to multiple destinations. The Web's traditional unicast client/server communication model suffers, however, when applied to webcasting; approaches that require many clients to simultaneously fetch data from the origin server using the client/server model will likely cause server and link overload. In this paper we describe a webcast design that improves upon previous designs by leveraging application level framing (ALF) design methodology. We build upon the Scalable Reliable Multicast (SRM) framework, which is based upon ALF, to create a custom protocol to meet webcast's scalability needs. We employ the protocol in an architecture consisting of two reusable components: a webcache component and a browser control component. We have implemented our design using a new SRM library called libsrm. We present the results of a simple performance evaluation and report on lessons learned while using libsrm.