A Web-Based Resource Migration Protocol Using WebDAV |
The web's hyperlinks are notoriously brittle, and break whenever a resource
Evans MP, Furnell SM
migrates. One solution to this problem is a transparent resource migration
mechanism, which separates a resource's location from its identity, and
helps provide referential integrity. However, although several such
mechanisms have been designed, they have not been widely adopted, due
largely to a lack of compliance with current web standards. In addition,
these mechanisms must be updated manually whenever a resource migrates,
limiting their effectiveness for large web sites. Recently, however, new web
protocols such as WebDAV (Web Distributed Authoring and Versioning) have
emerged, which extend the HTTP protocol and provide a new level of control
over web resources. In this paper, we show how we have used these protocols
in the design of a new Resource Migration Protocol (RMP), which enables
transparent resource migration across standard web servers. The RMP works
with a new resource migration mechanism we have developed called the
Resource Locator Service (RLS), and is fully backwards compatible with the
web's architecture, enabling all web servers and all web content to be
involved in the migration process. We describe the protocol and the new RLS
in full, together with a prototype implementation and demonstration
applications that we have developed. The paper concludes by presenting
performance data taken from the prototype that show how the RLS will scale
well beyond the size of today's web.