Document Type

Technical Report

Publication Date


Technical Report Number



An information agent is charged with the task of searching a collection of electronic resources for information that is relevant to the user's current needs. These resources are often distributed across a network and can contain tremendous quantities of data. One of the paradigms that has been suggested for allowing efficient access to such resources is transportable agents -- the agent is sent to the machine that maintains the information resource; the agent executes on this remote machine and then returns its results to the local machine. We have implemented a transportable agent system that uses the Tool Command Language (Tcl) as the agent language. Each Tcl script can suspend its execution at an arbitrary point, transport itself to another machine and resume execution on the new machine. The execution state of the script -- which includes the commands that have not been executed -- must be transmitted to the new machine. Although the execution state tends to be small, there will be a large number of agents moving across the network in a large-scale system. Thus it is desirable to compress the execution state as much as possible. Furthermore any compression scheme must be fast so that it does not become a bottleneck between the transportable agent system and the network routines. In this paper we explore several fast compression methods.