A Common Agent Platform
Jim White, General Magic, 11 March 1996
Submitted to the Joint W3C/OMG Workshop on
Distributed Objects and Mobile Code
In the last five years General Magic has developed
and deployed Telescript, a technology for mobile agents. This
paper sketches a common agent platform intended to allow
any number of such technologies to coexist and interoperate.
An agent is a program that a person or organization
vests with its authority, that can run unattended for a long time
(e.g., a week), and that can meet and interact with other agents.
The person or organization is the agent's authority.
One can distinguish two kinds of agent. A stationary
agent executes on one computer system. A mobile agent
can execute on different computer systems at different times of
Agents will be written in a variety of programming
languages. This creates a need for a common agent platform,
a language-independent means for agent interaction and mobile
agent migration. A server's implementation of the platform might
offer a full range of services; a PC's might offer a subset. An
application protocol would interconnect the implementations of
different systems so that their agents can interact and so that
their mobile agents can migrate between systems.
The platform would offer agent services to its clients.
These clients would include language environments, the
virtual machines and libraries for particular programming languages.
A language environment would offer some or all of the agent services
to programs written in that language.
The platform could provide services like these:
- Program naming. Assign
names to agent programs so as to distinguish one from another.
- Program authentication.
Authenticate the implementors of agent programs.
- Program migration.
Transport agent programs between computers. The name of a program
might be used to detect that it was already present at its destination.
- Agent naming. Assign
names to agents so as to distinguish one from another.
- Agent authentication.
Authenticate the authorities of agents.
- Agent migration. Transport
agents between computers. The mobile agentís destination
might be specified indirectly as the computer that hosts a specified
- Agent permissions.
Assign names to permissions, enforce an agentís assigned
permissions, and let one agent grant permissions to other agents
or re-negotiate its own.
- Agent relationships.
Assign names to relationships, let agents begin and end relationships,
and enforce rules of conduct for relationships.
- Agent creation. Let
agents create other agents locally and remotely. A new agent might
have the authority of the existing agent and either the same permissions
or a subset of them.
- Agent termination.
Terminate agents in an orderly fashion, e.g., by notifying other
agents with which they have relationships.
- Agent waiting. Write
to disk agents that must wait for long periods of time for events
to occur (e.g., for relationships to be established).
- Agent checkpointing.
Checkpoint agents to disk so that they survive crashes of their
host systems. A transaction service might coordinate the checkpointing
of related agents.
- Agent interaction.
Let related agents interact. The means of interaction (e.g., events,
pipes, and RPC) might depend upon whether the agents occupy the
same or different systems.
- Agent management.
Let network management and debugging agents monitor other agents.
A debugging agent, e.g., might be able to suspend and resume agents