Context-aware service discovery in mobile heterogeneous environments

To date, mobile services have failed to match the explosive growth of the Web. This, we argue, is because current mobile services are difficult to find, to use, to trust, to design and deploy. The IST SMS (Simple Mobile Services) project takes up the challenge of creating innovative tools addressing the specific needs of mobile users and making it easier for individuals and small businesses to become providers of Simple Mobile Services. In this paper, we focus on the first requirement of SMS: how to find a mobile service matching the user needs and appropriate for the user context. The contribution of this paper is twofold: first we formulate the context-aware service discovery problem in a heterogeneous mobile environment; then we propose a novel solution that provides mechanisms to discover services at every level of the service stack, from infrastructure services to end-user services. We propose a hybrid solution that combines the advantages of a directory-based solution and of a peer-to-peer fully distributed solution. The advantage of a fully distributed solution is the increase of efficiency in a local area. The advantage of a directory-based solution, exploiting an XML-based service discovery protocol and using a hierarchical organization of the directories, is that it allows obtaining a scalable and fault-tolerant system, which can be used both in a local and in a wide-area network.