Centaurus : A Framework for Intelligent Services in a Mobile Environment Lalana Kagal, Vlad Korolev, Harry Chen, Anupam Joshi, Timothy Finin Computer Science and Electrical Engineering University of Maryland Baltimore County email : lkagal1,vkorol1,hchen4,ajoshi,finin @cs.umbc.edu Abstract In an age where wirelessly networked appliances and de- vices are becoming commonplace, there is a necessity for connecting them to work together for a mobile user. The design outlined in this paper provides an infrastructure and communication protocol for providing ’smart’ services to these mobile devices. This flexible framework allows any medium to be used for communication between the system and the portable device, including infra-red, and BlueTooth. Using Extensible Markup Language for information pass- ing, gives the system a uniform and easily adaptable in- terface. We explain our trade-offs in implementation and through experiments we show that the design is feasible and that it indeed provides a flexible structure for providing ser- vices. Centaurus provides a uniform infrastructure for het- erogeneous services, both hardware and software services, to be made available to the users everywhere where they are needed. 1. Introduction As the world moves towards greater automation in homes and offices, we enter the realm of ‘SmartHomes’ and ‘SmartOffices’ controlled by sensors and/or portable devices, where not only has mobility been incorporated, but where intelligence has become an inherent part of providing services. Now-a-days, we see a lot of ‘intelligent’ services that use some kind of logical reasoning to provide better and more relevant support to individual users. These de- vices and services will have to be integrated seamlessly into the environment that the user is familiar with and provide a This research was supported in part by the DARPA DAML program under contract F30602-97-1-0215, by National Science foundation grants NSF IIS-9875433 and NSF CCR-0070802 and through a contract from Aether Systems Incorporated. In Proceedings of International Workshop on Smart Appliances and Wearable Computing (IWSAWC), at the The 21st International Conference on Distributed Computing Systems (ICDCS-21) April 16-19, 2001. uniform interface to any device that the user might want to use. Our goal is to provide an infrastructure and communi- cation protocol for wireless services, that minimizes the load on the portable device. While within a confined space, the Client can access the services provided by the nearest Centaurus System (CS) via some short-range communica- tion. The CS is responsible for maintaining a list of services available, and executing them on behalf of any Client that requests them. This minimizes the resource consumption on the Client and also avoids having the services installed on each Client that wishes to use them, which is a blessing for most resource-poor mobile clients. We also expect all Services to communicate via Exten- sible Markup Language (XML). We found this W3C Stan- dard [3] to be very useful in defining ontologies and describ- ing properties and interfaces of Services. As this is already being widely used, we think that it will help in integrating Centaurus with already existing systems. The information flowing in the system is strictly in the form of CCML (Cen- taurus Capability Markup Language) which is built on top of XML. To verify the feasibility of our infrastructure, we will use IR [8] for communication between the Client and the CS in our first stage of the development. One of the main draw- backs is the limitation of the infrared architecture. However, we believe that the simplicity and the affordability of the infrared devices can overcome these limitations. We would like to emphasize that any other medium could be used for communication including BlueTooth; all we provide is the framework. This paper is organized as follows: Section II discusses other technologies. In Section III, the design and modeling issues are covered with the actual implementation being de- tailed in Section IV. The communication protocol is briefly illustrated in Section V. The results of the experiments are described in Section VI, we discuss some of our future re- search areas in Section VII and Section VIII concludes the paper.