COM on a Multicast Transport

Due to the wide availability of the Internet and intranets, the use of multicast applications, such as document sharing, collaborative groupware and multimedia delivery, has grown quickly. Another trend in software developmen

Xept: A Software Instrumentation Method for Exception Handling

Modern software systems are often built from existing library components. A common problem is how to fix bugs when source code is not available. Xept is an instrumentation language and tool that can be used to add to object code the ability to detect, mask, recover and propagate exceptions from library functions. This helps to alleviate or avoid a large class of errors resulting from function misuses. Examples will be given to show applications of Xept in actual software systems. 1. Introduction Modern software systems are often built out of reusable components from diverse sources, including freeware or software vendors. For various reasons, including proprietary concerns, source code for such components is often not available. Thus, unless the original developers are still around and willing to help, bugs in such components are often left unfixed. This points out a need for tools and approaches to handle bugs in object code. This is not a generally solvable problem because bugs can a..

Design Strategies

With the explosive growth of the World Wide Web, some popular Web sites are getting thousands of hits per second. As a result, clients (browsers) experience slow response times and sometimes may not be able to access some Web sites at all. Upgrading the server nodes to more powerful machines may not always be cost-effective. A natural solution is to deploy a set of machines, or a cluster, and have them work together to host a single service. Such a server cluster should preferably publicize only one server name for the entire cluster so that any configuration change inside the cluster does not affect client applications. In this paper, we first discuss existing approaches to distributing client's requests for a single service to different machines in a cluster. We then propose two new techniques, collectively called ONE-IP, based on dispatching packets at the IP level. They have the advantages of fast dispatching and ease of implementation. Ideas presented here are generic and should be applicable to other services as well