Thirteenth Ph.D.: unlucky for some?
Not for Mikhail Mikhailov, as the Computer Science Department has awarded him its thirteenth Ph.D. degree. The advisor was Craig Wills.
Mikhail successfully defended his thesis in public before his Ph.D. committee on January 3, 2003. His committee consisted of WPI Profs. Craig Wills, Robert Kinicki, and David Finkel, with Dr. Balachander Krishnamurthy of AT&T Labs.
His thesis title is "Deterministic Object Management in Large Distributed Systems".
Thesis Abstract:
Caching is a widely used technique to improve the scalability of distributed systems. A central issue with caching is maintaining object replicas consistent with their master copies. Large distributed systems, such as the Web, typically deploy heuristic-based consistency mechanisms, which increase delay and place extra load on the servers, while not providing guarantees that cached copies served to clients are up-to-date. Server-driven invalidation has been proposed as an approach to strong cache consistency, but it requires servers to keep track of which objects are cached by which clients.
We propose an alternative approach to strong cache consistency, called MONARCH, which does not require servers to maintain per-client state. Our approach builds on a few key observations. Large and popular sites, which attract the majority of the traffic, construct their pages from distinct components with various characteristics. Components may have different content types, change characteristics, and semantics. These components are merged together to produce a monolithic page, and the information about their uniqueness is lost.
In our view, pages should serve as containers holding distinct objects with heterogeneous type and change characteristics and preserving the boundaries between these objects. Servers compile object characteristics and information about relationships between containers and embedded objects and piggyback it onto existing request/response traffic. This knowledge is used by clients (caches) to make object management decisions.
We evaluated MONARCH using simulations with content collected from real Web sites. The results show that MONARCH provides strong cache consistency for all objects, even for unpredictably changing ones, and incurs smaller byte and message overhead than heuristic policies. The results also show that as the request arrival rate or the number of clients increases, the amount of server state maintained by MONARCH remains the same while the amount of server state incurred by server invalidation mechanisms grows.
Dr. Mikhailov has a Diploma with Honors from the Business School of the American University in Moscow, Russia, as well as a joint BS/MS in Computer Science from Moscow Bauman State Technical University. He has been at WPI since August 1995. He has already published two journal articles on his research with Craig Wills, as well as six conference papers.
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