SIMULTANEOUS MULTIPLE VERSIONS: THE KEY TO THE WOS

The rapid development and the heterogeneous nature of the We b ensure that it is impossible to develop a complete catalog of all of the resources and serv ices available on the Web. As a result, no single operating system can be used for Web comput ation, since it will necessarily be incomplete. Furthermore, it is unclear that such an opera ting system would even be useful, considering the different levels of granularity of service that need to be provided. The Web Operating System (WOS TM ) approach to Web computation envisages a series of versioned servers, possibly offering different services, themselves versioned, that use the same basic protocol for communication amongst themselves, and t hat are capable of passing on requests for service when appropriate. The WOS is not defined by the actions of any single server but, rather, by the combined actions of the different s rvers. Key to the successful implementation of the WOS is the abilit y for multiple different versions of the WOS to interact in a meaningful manner, and that a reque st for service be passed on to a server actually capable of managing that request. Each WOS server will have a version tag, which can be readily t ranslated into a fixed catalog of guaranteed services. In addition, a WOS server mi ght offer additional services, either offered en masse in an additional catalog, or one at a t ime, on demand. Once presented in this manner, the problem becomes one of dis tributed software configuration management. There is no single repository in which all p ossible versions are stored, and there is no means for recuperating all of the possible versio ns. In this paper, we show how these problems can be addressed by generalizing standard techniq ues.