Mobile Agents
 

• Moving from host to host to reach the goal

• Main issues:

                 Carring data and code

                 Continuing where it stopped
 
 

           Autonomy:
 
 

                 The more sophistication - the less interactions

                 The ability to plan own actions and routes
 
 
 

    Advantages
 
 

• Multi-processor calculations

• Low-reliability networks

• User passivity (e.g., E-mail deliverer)

  Structure of the Mobile System Infrastructure

• Agent Server

• Administration
• Security
• Transfer

• Agent

• Migrates between servers
• Communicate with servers and other agents
• Completes the tasks

        Note:

                    Agents can migrate only between Agent Servers!
 
 
 

• RMI and serialization

• Sockets

  Communication Mechanisms  
 
 

• Procedure calls

• Synchronous
• Difficult to do in parallel

• Callback mechanism

• Asynchronous
• Complicated

• Mailbox mechanism

• Asynchronous
• Difficult to implement

• Broadcast

        Java Based Tools
 
 
 

• Pure Java - JDK 1.1 or later:

• Providing classes and methods:

• Providing the Agent Server:

• Loading the code from variety of sources

• Aglet by IBM’s Tokyo Research Lab

       - Mobile applets
 
 

• Voyager by Object Space

     - All serializable objects are mobile!
 
 

• Odyssey by General Magic

     - Distributed mobile applications
 
 

• Concordia by Mitsubishi Electric ITCA

    - Collaborative mobile agents
 
 
 

    Comparisons
 

Agent System	Aglets	Concordia	Odyssey	Voyager
GUI	Yes	Yes	No	Yes
Modular Design	No	Yes	No	No
Mobility Mechanism	Sockets	RMI	RMI	RMI
Persistence	None	Implicit	None	Explicit
Lifespan	Explicit	Explicit	Explicit	5 types
Security	Security Manager	Security Manager	Java based	Restricted operations
Direct  agent-agent comm.	Yes	No	No	Yes
Receive messages  when moving	No	Yes	No	Yes
Comm. types provided	Sync Async Broadcast	Groupevents Filteredevents Collaboration	None	Sync  Async Mailbox Broadcast

 
 
 

    References:
 
 

[3.] Sundsted, T., "Agents Talking to Agents, " Javaworld, September 1998.

http://www.javaworld.com/jw-09-1998/jw-09-howto.html

[4.] Kiniry, J., Zimmerman, D., "A Hands-On Look at Java Mobile Agents, "

IEEE Internet Computing, Volume I, Number 4, July/August 1997.

csvax.cs.caltech.edu/~kiniry/projects/papers/IEEE_Agents/agents_paper/

[5.] Shah, K., Guota, R., Timm, S., "Study of Mobile Agent Systems, "

Department of Computer Science, Virginia Tech, Blachsburg, Virginia, USA, 1998.

http://csgrad.cs.vt.edu/~stimm/agents/
[6.] IBM Aglets Workbench, A White Paper, IBM Tokyo Research Laboratory, Tokyo, Japan, 1996.,

http://www.trl.ibm.co.jp/aglets/
[7.] ObjectSpace Voyager Core Package Technical Overview, ObjectSpace, Dallas, Texas, USA,

December 1997.

http://www.objectspace.com/voyager/whiteparer/

[8.] Introduction to The Odyssey API, General Magic, Sunnyvale, California, USA, 1997.

http://www.genmagic.com/agents/odysseyIntro.ps

[9.] Concordia: An Infrastructure for Collaboration Mobile Agents, Mitsubishi Electric ITA,

Waltham, Massachusetts,USA, 1997.

http://www.meitca.com/HSL/Projects/Concordia/

[10] Horvat, D., Milutinovic, V., "A Survey of Mobile Agents and Java Mobile Agents Toolkits,"
Internal Report, University of Belgrade, Yugoslavia, December 1998.

http://galeb.etf.rs/~vm/tutorial/internet/business/ebi2/ebi4.html