A theory of retractable and speculative contracts

International audienceBehavioral contracts are abstract descriptions of expected communication patterns followed by either clients or servers during their interaction. Behavioral contracts come naturally equipped with a notion of compliance: when a client and a server follow compliant contracts, their interaction is guaranteed to progress or successfully complete. We study two extensions of behavioral contracts, retractable contracts dealing with backtracking and speculative contracts dealing with speculative execution. We show that the two extensions give rise to the same notion of compliance. As a consequence, they also give rise to the same subcontract relation, which determines when one server can be replaced by another preserving compliance. Moreover, compliance and subcontract relation are both decidable in quadratic time. Finally, we study the relationship between retractable contracts and calculi for reversible computing

Retractability, games and orchestrators for session contracts

Session contracts is a formalism enabling to investigate client/server interaction protocols and to interpret session types. We extend session contracts in order to represent outputs whose actual sending in an interaction depends on a third party or on a mutual agreement between the partners. Such contracts are hence adaptable, or as we say "affectible". In client/server systems, in general, compliance stands for the satisfaction of all client's requests by the server. We define an abstract notion of "affectible compliance" and show it to have a precise three-party game-theoretic interpretation. This in turn is shown to be equivalent to a compliance based on interactions that can undergo a sequence of failures and rollbacks, as well as to a compliance based on interactions which can be mediated by an orchestrator. Besides, there is a one-to-one effective correspondence between winning strategies and orchestrators. The relation of subcontract for affectible contracts is also investigated

Retractability, games and orchestrators for session contracts

Session contracts is a formalism enabling to investigate client/serverinteraction protocols and to interpret session types. We extend sessioncontracts in order to represent outputs whose actual sending in an interactiondepends on a third party or on a mutual agreement between the partners. Suchcontracts are hence adaptable, or as we say "affectible". In client/serversystems, in general, compliance stands for the satisfaction of all client'srequests by the server. We define an abstract notion of "affectible compliance"and show it to have a precise three-party game-theoretic interpretation. Thisin turn is shown to be equivalent to a compliance based on interactions thatcan undergo a sequence of failures and rollbacks, as well as to a compliancebased on interactions which can be mediated by an orchestrator. Besides, thereis a one-to-one effective correspondence between winning strategies andorchestrators. The relation of subcontract for affectible contracts is alsoinvestigated