Replication is an essential feature of a distributed

Replication is an essential feature of a distributed system, but updates cause the issue of consistency between replicas. Strong consistency is easy to understand but impossible in peer 2 peer environment; weaker models are complex. Our Actions-Constraints Framework (ACF) provides a formal model for modelling, comparing, and reasoning about consistency. Developers of distributed collaborative applications in Peer 2 Peet environment need decentralized P 2 P replication middleware and consistency protocols. Telex is a Peer 2 Peer semantic-oriented middleware based on Actions-Constraints Framework. However, it is not intuitive for collaborative-application developers to express application semantics using the ACF. In fact, the application design is ad-hoc and hard to validate. I aim to facilitate Peer 2 Peer collaborative application design. For that purpose, I propose a generic methodology for more principle designing, an extension of the ACF to facilitate expressing the application semantics, and a use of automatic prover to validate the application design. Shared Calendar Application Share Calendars Calendar Conflict Non Commuting Calendar Telex Middelware Actions-Constraints Framework (ACF) Action Telex Advantages J P 2 P middleware J Replication J Consistency Future Challenges ACF Extension J Asynchronous q Hybridizing ACF and State -Based replication: J Disconnected work Correlate constraints with a state. Challenges L Ad-hoc design Dynamic constraints L Non intuitive Future Challenges Design Tools 2 Constraint L Describe application semantics: 2 1 L Static Constraints L Hard to validate q. Automatic Prover ü Actions ü Constraints ü Invariants Validation / Count examples Methodology: q. Any information ü Implicit/Explicit ü Shared ü Consistency Explicit Telex Object 1 Lamia BENMOUFFOK _ Marc SHAPIRO Lip 6/INRIA REGAL Team _ Paris 6 University Lamia. Benmouffok@lip 6. fr