What do Grid and P2P have to do with each other? Adriana Iamnitchi and I wrote a paper on that question a few years ago. The title is "On Death, Taxes, and the Convergence of Peer-to-Peer and Grid Computing", which we explained as follows:
It has been reported that life holds but two certainties, death and taxes. And indeed, it does appear that any society-and in the context of this article, any large-scale distributed system-must address both death (failure) and the establishment and maintenance of infrastructure (which we assert is a major motivation for taxes, so as to justify our title!).
We wrote further:
Two supposedly new approaches to distributed computing have emerged in the past few years, both claiming to address the problem of organizing large-scale computational societies: peer-to-peer (P2P) and Grid computing. Both approaches have seen rapid evolution, widespread deployment, successful application, considerable hype, and a certain amount of (sometimes warranted) criticism. The two technologies appear to have the same final objective-the pooling and coordinated use of large sets of distributed resources-but are based in different communities and, at least in their current designs, focus on different requirements.
In this article, we take some first steps toward comparing and contrasting P2P and Grid computing. Basing our discussion whenever possible on the characteristics of deployed systems, rather than the unverified claims abundant in the literature, we review their target communities, resources, scale, applications, and technologies. On the basis of this review, we draw some initial conclusions concerning their interrelationship and future evolution. In brief, we argue that:
- both are concerned with the same general problem, namely, the organization of resource sharing within virtual communities;
- both take the same general approach to solving this problem, namely the creation of overlay structures that coexist with, but need not correspond in structure to, underlying organizational structures;
- each has made genuine technical advances, but each also has-in current instantiations-crucial limitations, which we characterize (simplistically, but, we believe, usefully) as "Grid computing addresses infrastructure but not yet failure, whereas P2P addresses failure but not yet infrastructure"; and
- the complementary nature of the strengths and weaknesses of the two approaches suggests that the interests of the two communities are likely to grow closer over time.
Since we wrote that paper in 2004, there have been some interesting developments that point perhaps to convergence of interests, if not technology and community. For example, the P2P research community has been building substantial infrastructure, in the form the PlanetLab system, and the Grid community has been building increasingly resilient and decentralized services: for example, the Globus Replica Location Service and the various services that support the Open Science Grid. It will be interesting to see where things go from here.