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SUMMARY:Concurrency and Dynamic Protocol Update for Group Communication Mi
 ddleware
DTSTART:20090123T171500
DTSTAMP:20260407T042116Z
UID:15851b0e5ec93be5ef0e500cfb9e2efe3ee583d27912873a582fb488
CATEGORIES:Thesis defenses
DESCRIPTION:Olivier Rütti\nThe last three decades have seen computers inv
 ading our society: computers are now present at work to improve productivi
 ty and at home to enlarge the scope of our hobbies and to communicate. Fur
 thermore\, computers have been involved in many critical systems such as a
 nti-locking braking systems (ABS) in our cars\, airplane control systems\,
  space rockets\, nuclear power plants\, banking and trading systems\, medi
 cal care systems\, and so on. The importance of these systems requires a h
 igh level of trust in computer-based systems. For example\, a failure in a
  trading system (even if it is temporary) may result in severe economical 
 losses. Hence coping with failures is a key aspect of computer systems.\nA
  common approach to tolerate failures is to replicate a system that provid
 es a critical service\, so that once a failure occurs on a given replica\,
  the requests to the critical service are still executed by other replicas
 . This approach has the advantage of masking failures\, i.e.\, requests to
  the service are continuously executed even in the presence of failures. H
 owever\, replication introduces a performance cost\, mainly because the ex
 ecution of the service requests must be coordinated among all replicas. Fu
 rthermore\, despite its apparent simplicity\, replication is rather comple
 x to implement. Replication is made easier by group communication which de
 fines several abstractions that can be used by the designer of replicated 
 systems. The group communication abstractions are implemented by distribut
 ed protocols that compose a group communication middleware.\nThe aim of th
 e thesis is to study two techniques to improve the performance of group co
 mmunication middleware\, and thus\, reduce the cost of replication. First\
 , we study dynamic protocol update\, which allows group communication midd
 leware to adapt to environment changes. More particularly\, dynamic protoc
 ol update consists in replacing at runtime a given protocol composing the 
 group communication middleware with a similar but more efficient protocol.
  The thesis provides several solutions to dynamic protocol update. For ins
 tance\, we describe two algorithms to dynamically replace consensus and at
 omic broadcast\, two essential protocols of a group communication middlewa
 re. Second\, we propose solutions to introduce concurrency within a group 
 communication middleware in order to benefit from the advantages offered b
 y multiprocessor (or multicore) computers.
LOCATION:INF 213
STATUS:CONFIRMED
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