Representing Conversations for Scalable Overhearing

TL;DR

This paper evaluates existing Petri net methods for representing agent conversations, introduces a new Colored Petri net approach that improves scalability and coverage, and provides a transformation procedure from AUML diagrams.

Contribution

It presents a novel Colored Petri net representation for agent conversations, enhancing scalability and standard coverage, along with a transformation method from AUML diagrams.

Findings

The new Colored Petri net approach outperforms existing methods in scalability.

It provides comprehensive coverage of FIPA conversation features.

The transformation procedure from AUML diagrams is effective and practical.

Abstract

Open distributed multi-agent systems are gaining interest in the academic community and in industry. In such open settings, agents are often coordinated using standardized agent conversation protocols. The representation of such protocols (for analysis, validation, monitoring, etc) is an important aspect of multi-agent applications. Recently, Petri nets have been shown to be an interesting approach to such representation, and radically different approaches using Petri nets have been proposed. However, their relative strengths and weaknesses have not been examined. Moreover, their scalability and suitability for different tasks have not been addressed. This paper addresses both these challenges. First, we analyze existing Petri net representations in terms of their scalability and appropriateness for overhearing, an important task in monitoring open multi-agent systems. Then, building on the insights gained, we introduce a novel representation using Colored Petri nets that explicitly represent legal joint conversation states and messages. This representation approach offers significant improvements in scalability and is particularly suitable for overhearing. Furthermore, we show that this new representation offers a comprehensive coverage of all conversation features of FIPA conversation standards. We also present a procedure for transforming AUML conversation protocol diagrams (a standard human-readable representation), to our Colored Petri net representation.