An Overview of Jason

Current trends in computer science such as the semantic web, ubiquitous computing, and self-* systems make it increasingly important that programming technology suitable for open, unpredictable, dynamic environments are made available. Many abstractions and techniques that emerged from research in multi-agent systems can have major impact in the effectiveness of (the development of) such systems. Research into agent-oriented programming languages aims at making such abstractions and techniques readily available at the level of programming languages. In this perspective, agent-oriented programming, combined with ongoing work on agent-oriented software engineering, is likely to lead to a popular new paradigm for the practical development of those complex distributed systems. One of the most studied architectures for cognitive agents is the BDI (Beliefs-DesiresIntentions) architecture. In the area of agent-oriented programming languages in particular, AgentSpeak(L) is one of the best known languages based on the BDI architecture. AgentSpeak(L) is an abstract logic-based agent-oriented programming language introduced by Rao [8], and subsequently extended and formalised in a series of papers by Bordini, Hübner, and various colleagues. Practical BDI agents are implemented as reactive planning systems : they run continously, reacting to events (e.g., perceived changes in the environment) by executing plans given by the programmer. Plans are courses of actions that agents commit to execute so as achieve their goals. The pro-active behaviour of agents is possible through the notion of goals (desired states of the world) that are also part of the language in which plans are written. Jason is a Java-based platform for the development of multi-agent systems. At the core of the platform lies an interpreter for an extended version of AgentSpeak(we use “AgentSpeak” to refer to the various extensions of the original AgentSpeak(L) language). We cannot introduce the language in this short article; a good description of the Jason language and platform can be found in [4]. Various ad hoc implementations of BDIbased (or “goal-based”) systems exist, but one important characteristic of AgentSpeak