Draft:Information protocols

Information protocols is a declarative approach for specifying interaction protocols. The approach was invented in 2011 by Munindar P. Singh to address the challenge of modeling flexible interactions between agents.

Idea

Flexible Purchase involve two roles, Buyer and Seller. It specifies several messages, each with sender, receiver, and several parameters, some of which are key parameters. For example, Request is a message from Buyer to Seller and has parameters ID, which is key, and item. Key parameters uniquify instances of a message and enable correlation.

Adornment out, in, and nil in the messages specify causality and constrain the emission of the message by the sender. Let us define the local state of an agent to be the set of messages it has sent and received. An agent can send an instance of a message provided none of the parameters adorned out or nil are known in the local state and all the in parameters are known in the local state.

Flexible Purchase {
 role Buyer, Seller
 parameter out ID key, out item, out status, out paid

 Buyer -> Seller: Request[out ID key, out item]
 Seller -> Buyer: Shipment[in ID key , in item, out status]
 Buyer -> Seller: Payment[in ID key, in item, out paid]
}