—Multi-agent systems are difficult to develop. One reason for this is that agents are embedded in a society where all agents must agree to obey certain social norms in order for the society to function. Thus, different programmers, writing different agents, must carefully obey certain agreed-upon protocols. This problem is difficult enough due to the complexity of the interactions, but it is exacerbated by the asynchronous and eventbased nature of agent-based systems: agents must asynchronously respond to incoming conversational messages, and may carry on several simultaneous conversations. Several large projects address these issues. Examples are Jade (Telecom Italia) and Cougaar (DARPA). Jade is strictly compliant with the well-known FIPA standard, which makes it useful for commercial agent development and research not directed at certain fundamental aspects of multi-agent systems. Cougaar was developed as a defense agent infrastructure, and while it is not tied to FIPA standards...