Decentralised Commitment for Optimistic Semantic Replication

Abstract. We study large-scale distributed cooperative systems that use optimistic replication. We represent a system as a graph of actions (operations) connected by edges that reify semantic constraints between actions. Constraint types include conflict, execution order, dependence, and atomicity. The local state is some schedule that conforms to the constraints; because of conflicts, client state is only tentative. For consistency, site schedules should converge; we designed a decentralised, asynchronous commitment protocol. Each client makes a proposal, reflecting its tentative and/or preferred schedules. Our protocol distributes the proposals, which it decomposes into semantically-meaningful units called candidates, and runs an election between comparable candidates. A candidate wins when it receives a majority or a plurality. The protocol is fully asynchronous: each site executes its tentative schedule independently, and determines locally when a candidate has won an election. ...

• Type: Conference
• Year: 2007
• Where: OTM
• Authors: Pierre Sutra, João Barreto, Marc Shapiro
• Keywords: And/or Preferred Schedules, Asynchronous Commitment Protocol, Internet Technology, OTM 2007, Semantic Constraints