Global session types are behavioral types designed for specifying in a compact way multiparty interactions between distributed components, and verifying their correctness. We take advantage of the fact that global session types can be naturally represented as cyclic Prolog terms - which are directly supported by the Jason implementation of AgentSpeak - to allow simple automatic generation of self-monitoring MASs: given a global session type specifying an interaction protocol, and the implementation of a MAS where agents are expected to be compliant with it, we define a procedure for automatically deriving a self-monitoring MAS. Such a generated MAS ensures that agents conform to the protocol at run-time, by adding a monitor agent that checks that the ongoing conversation is correct w.r.t. the global session type. The feasibility of the approach has been experimented in Jason for a non-trivial example involving recursive global session types with alternative choice and fork type constructors. Although the main aim of this work is the development of a unit testing framework for MASs, the proposed approach can be also extended to implement a framework supporting self-recovering MASs.

In this paper we investigate the theoretical foundations of global types for dynamic checking of protocol compliance in multi-agents systems and we extend the formalism by introducing a concatenation operator that allows a significant enhancement of the expressive power of global types. As examples, we show how two non trivial protocols can be compactly represented in the formalism: a ping-pong protocol, and an alternating bit protocol, in the version proposed by Deni'elou and Yoshida. Both protocols cannot be specified easily (if at all) by other global type frameworks, while in our approach they can be expressed by two deterministic types (in a sense made precise in the sequel) that can be effectively employed for dynamic checking of the conformance to the protocol.