Agent Development Support for Tcl

In the past few years, the explosive g r o wth of the Internet has allowed the construction of "virtual" systems containing hundreds or thousands of individual , relatively inexpensive computers. The agent paradigm is well-suited for this environment because it is based on distributed autonomous computation. Although the deenition of a software agent v aries widely, some common features are present in most deenitions of agents. Agents should be autonomous, operating independently of their creator(s). Agents should have the ability t o m o ve freely about the In-ternet. Agents should be able to adapt readily to new information and changes in their environment. Finally, agents should be able to communicate at a high level, in order to facilitate coordination and cooperation among groups of agents. These aspects of agency provide a dynamic framework for the design of distributed systems. Tcl is an ideal language with which to build agents, because scripts written in Tcl may b e u s e d on any m a c hine that can run Tcl, and because the Tcl language environment itself is highly portable. Additionally, Tcl/Tk greatly facilitates rapid proto-typing and quick d e v elopment of small applications. We present TKQML, the integration of an agent communication language, KQML 6] (K n o wl-edge Query Manipulation Language) into Tcl/Tk. TKQML can be used to build KQML-speaking agents that run within a TKQML shell. TKQML can also be used to bind together diverse applications into a distributed framework, using KQML as a communication language. Tcl's embeddable nature allows one to easily add agent c o m m unication facilities to existing code. As such, TKQML can be used to enhance the functionality of new or existing systems built using a Tcl framework, by a l l o wing easy integration with agent-based systems. KQML is a language for general agent communication. It was developed as part of the Knowledge Sharing EEort 7], a DARPA project exploring agent communication and knowledge reuse. KQML is a language based on speech acts, such as \tell", \ask", and \deny", which describe the nature of a message without reference to its content. Agents communicate application-speciic information embedded in general, higher-level KQML messages. A comprehensive semantics 4] for KQML outlines protocols for agent \conversation." Additionally, most implementations provide facilities for message handling, agent naming and resource brokering. Problems of software mobility, c o m m unication, and …