Choreography is an emerging technique for the design of extended peer-to-peer service collaborations, such as those used in supply chain and some complex financial trades. These are collaborations in which participants communicate by sending messages to each other, with different participants able to send messages at the same time.

However, because there is no central co-ordinator that sees all the messages, a given participant has only partial knowledge of the full state of the collaboration. This presents a design challenge, as you have to ensure that these partial understandings do not diverge resulting in a muddle. This talk will describe how choreography based techniques can ensure that such divergence is not possible.