AFS and the web: competitors or collaborators?

Over the last few years, the World-Wide Web [2] has risen to dominance as a mechanism for wide-area information access. Each day brings new reports of the growth of the Web, and this trend shows no signs of abating any time soon. To many people, the Web and the Internet are synonymous. Unfortunately, success has exposed many limitations of the Web such as its tendency to overload the network and servers, its limited ability to control access to sensitive data, its lack of mechanisms for data consistency, and its susceptibility to network and server failures. It is now widely recognized that these problems must be solved for the continued growth of the Web.With much less fanfare, another world-wide information system, AFS, has also been operational on the Internet. AFS was originally designed to support the file sharing needs of a campus-sized community of five to seven thousand workstations [11, 15]. In current parlance, AFS was conceived as an information sharing mechanism for the Intranet of an organization. Since then, AFS has been evolved to function effectively over the Internet [17, 21]. Many organizations have been part of a single distributed Unix file name space supported by AFS. As of 1994, this system spanned well over 100 organizations world-wide, with each organization typically containing many tens or hundreds of clients. Measurements reported in a recent paper [20] confirm that AFS does indeed function effectively at this scale.The goal of this paper is to critically compare these two mechanisms for world-wide information access. We begin by asking the following questions:• What are the relative strengths and weaknesses of the two mechanisms?• Which of these differences are superficial, and which are deep?• Why is the Web so much more visible and popular?In performing this comparison, it is important to keep in mind that the two mechanisms are not addressing precisely the same problem. While AFS has the relatively narrow and well-defined goal of provided distributed Unix file access, the goal of the Web is broader and less explicit. Further, AFS is now stable and mature while many aspects of the Web are still evolving. In spite of these caveats, we believe that a comparison of the two mechanisms will provide useful insights.Our comparison shows that the Web and AFS are not really competing technologies. Rather, they represent complementary technologies that may be used together for mutual advantage. We present real-life examples to confirm that this potential can indeed be realized in practice.