Transportable Agents

As network information resources grow in size, it is often most efficient to process queries and updates at the site where the data is located. This processing can be accomplished by using a traditional client-server network interface, which constrains the client to the set of queries supported by the server, or requires the server to send all data to the client for processing. The former is inflexible; the latter is inefficient. Transportable agents, which support the movement of the client computation to the location of the remote resource, have the potential to be more flexible and more efficient. Transportable agents are capable of suspending their execution, transporting themselves to another host on a network, and resuming execution from the point at which they were suspended. Transportable agents consume fewer network resources and can support systems that do not have permanent network connections, such as mobile computers and personal digital assistants. We describe a prototype transportable-agent implementation that facilitates research in this area. Agents are written in a script language that supports agent relocation, and the language is processed at each host by an agent interpreter. Electronic mail and UNIX remote shell (rsh) are the two current transport mechanisms and we plan to explore others. We present a technical-report searching agent as a demonstration of the capabilities of our prototype implementation.