Mobile Communications in a Mobile Agent Based Overlay System Ching-Feng Li

2 Issues of Mobile Agent Communication  The receiver agent may migrate to another peer  How does the sender agent know the receiver agent has migrated?  How does the sender agent know the latest location of the receiver agent?  Message reliability  The receiver agent may crash when the peer it resides crash. How to ensure that the receiver agent does not miss any message?

3 MCP C Sender agent MCP AMCP B Receiver agent Communication request Target agent is not here Receiver agent migrated before sender agent tries to communicate with it

4 MCP C / HCP of agent C Agent A MCP A / HCP of agent A MCP B / HCP of agent B Agent B Sending message Connection failed Receiver agent crashed before sender agent tries to communicate with it

5 Mechanism for solving the mobile agent migration issue  Terms  MCP – Mobile Context Peer  When a mobile agent migrates from MCP A to MCP B, the mobile agent sends a message to MCP A to update its new location.  The agent can also publish its new location to the overlay network  Before making a communication, the sender agent finds the current location of the receiver agent

6 MCP C Sender agent MCP AMCP B Receiver agent Communication request Mechanism for solving the mobile agent migration issue Update its new location Forward communication request

7 Mechanism for solving the message reliability issue  Terms  MCP – Mobile Context Peer  HCP – Home Context Peer  Every MCP in the overlay system provides the “messaging- queue service”  The HCP of a mobile agent serves as the messaging-queue server of the mobile agent  The mobile agent publishes its HCP to the overlay network  Every message sent to a mobile agent will also be sent to its HCP if there is an error while sending the message  The message-queue will be checked when the mobile agent re-starts and then periodically

8 MCP C / HCP of agent C Agent A MCP A / HCP of agent A MCP B / HCP of agent B Agent B Send message Connection failed Mechanism for solving the message reliability issue Send message Check the message queue when re-starts, and then periodically Retrieved the lost messages.