Members

Françoise André, Erwan Saint Pol

Motivations and objectives

Nowadays wireless computing is becoming a reality. This enables to be connected to networks while on the move, for example to "surf "on the Internet when travelling by train. But wireless networks still suffer from drawbacks, primarily low bandwidth and high latency communication. Moreover mobile devices toda have limited battery capacity and limited memory resources. The unreliabilit of the environment in which mobile users operate may cause voluntary or involuntary disconnections with the fixed networks. A system is neede to deal with these drawbacks for client/server applications on the Internet.

Application domains and experiments

We have designed and realized a middleware that permits the user to work in disconnected mode. The main idea is to execute a transaction entirely on the mobile devic and to commit it on the database server on reconnection. This solution requires a local transaction manager to execute transactions on the mobile computer, a cache to store data that are likely to be used during a disconnection and a global transaction manager for committing the "locally committed" transactions. Protocols to store data in the cache, to solve inconsistencies on reconnection are defined. The integration in the WEB framework is realized through the use of a proxy which acts as a WEB server on the mobile.

This system has been applied to an Electronic Commerce application in the framework of the European project Agent-isme.

It has contributed to the design of the MolèNE system .

Publications