1. Mobile Agents

2. Agent system implements the agent paradigm
What is an agent?
A program that acts on behalf of a user
Represents the user into the network
Migrates autonomously in the network
Performs computations on behalf of the user
Path of the agent
Predetermined
Agents determine dynamically
Reduce n/w use
Increase asynchrony between clients & servers
Add client specified functionally to servers &
Introduce concurrency
Agent system implements the agent paradigm

3. parameters RPC server client data procedure server client Results S2
REV
Agent migration
Mobile agents S2 S1
Agent migration
Agent dispatch
Agent migration S3
client

4. Repeated client-server interactions
Bandwidth, Flexibility, Mobility
Repeated client-server interactions
Maintain connections over long periods
Several separate requests
No need for continuous connection with the use of mobile agents
Resource can be freed up for other use
Particularly useful in mobile computers
Not connected all the time

5. Mobile agents RPC for controlling a device/instrument? parameters
Client can maintain its own interface at the server node – a mobile agent serves as a proxy
A given task can be divided into multiple tasks and distributed among mobile agents – achieve parallelism
Mobile agent paradigm can be used
For low level system management
For middleware user-level applications
RPC for controlling a device/instrument?
parameters
server
client
data
Back and forth several time

6. Agent application Low level Middleware – user applications
Network maintenance
Testing and fault diagnosis
Installation and software upgrade
Middleware – user applications
Electronic market place
Active mail messages

7. Agent Server Agent code execution Primitive operations Migrate
Communicate
Access resources
Application specific services

8. Migration Server Server
State : Thread’s execution context and call stack
Deactivate
Capture state &
transmit
Receive
Restore agent state
Reactivate

9. Transfer code Agent carries all the code with it Execute on any server
Agent code preinstalled on servers
Does not carry code
Reference to Code base
A code server keeps all the code

10. Naming
Tacking an agent
Agent
Agent Server

11. Location transparent names
Location dependent
Easy to implement
Cumbersome to track
Location transparent names
Complex - encapsulation
System updates location info when MA moves
Global Location independent names
Do not change when the entity relocates
Name service maps symbolic names to the current location

12. Security Agent Privacy and integrity Agent and server authentication
Part of the agent system may be sensitive
Agent may not trust all servers
Selective – servers
Security breaches in the code – hard to prevent but detectable
Secure communication
Agent and server authentication
Identity – digital signatures
Authorization and access control
Metering, charging and payment mechanisms

13. Agent programming primitives
Basic agent management
Agent-to-agent communication and synchronization
Agent monitoring and control
Fault-tolerance
Security related

15. Coordination Client-server Message-oriented Blackboard Linda-like
Blackboard + associative mechanisms
Tuple spaces – access by content rather than id