Mobile Web Services based Middleware for Context-Aware Applications

Mobile devices, communication systems and applications increasingly become more complex. In order to manage mobile distributed applications a middleware is essential which simplifies and speeds up the application development. A mobile environment with its heterogeneity and mobility has different requirements compared to a fixed environment. Thus, new concepts and mechanisms for a middleware have to be developed to cope with the challenge of these heterogeneous distributed systems. In this article, we introduce a Web Service based middleware for mobile devices, adapted to a mobile environment with special focus on context-awareness. The contextawareness will be realized by a rule based data monitoring in order to minimize the communication frequency over the mobile links and, thus, to minimize the runtime costs of the mobile application. Within this middleware mobile context providers are able to publish their context-data. This data can be remotely monitored by subscribing to a service of the context-provider and receiving notifications from the context provider. The Web Service based mobile middleware will be described in general, special focus is given to the rule based data monitoring for context-aware applications. In addition a discussion of the expected application runtime costs regarding the communication is given.