Proxy-based recovery for applications on wireless hand-held devices

Abstract

The low communication bandwidth, slow processor and limited memory of hand-held devices make it undesirable for them to store their own checkpoints or send process state information over a wireless network. The paper describes an approach to failure recovery for three-tier client and server application environments where the client applications execute on wireless handheld devices. The key idea is to have the middle-tier proxy transparently monitor the client's interaction with the back-end server and continuously maintain a copy of the client's state based on messages exchanged between the client and the server. The proxy also sustains the client's connection to the back-end server when a client unexpectedly disconnects. The client does not participate in checkpointing nor message logging, thereby saving power, processor cycles and bandwidth. The proxy is scalable and enhances backend server performance. Experimental results are provided for recovery time and runtime overhead.