Choreographies in the wild

• We propose a theory for bottom-up service composition in open networks.
• Each service advertises its promised behaviour with a contract.
• A multiparty session is created if contracts allow to construct a well-formed choreography.
• Our framework accounts for services that may not respect their contracts at runtime.
• We show that systems of “honest” services enjoy progress and session fidelity.

We investigate the use of choreographies in distributed scenarios where, as in the real world, mutually distrusting (and possibly dishonest) participants may be unfaithful to their expected behaviour. In our model, each participant advertises its promised behaviour as a contract. Participants may interact through multiparty sessions, created when their contracts allow to synthesise a choreography. We show that systems of honest participants (which always adhere to their contracts) enjoy progress and session fidelity.