在我們的生活中已經有越來越多的裝置擁有上網的能力。然而，當這些裝置存取網路上的資源時，無論是其使用者的喜好、裝置的能力及網路的特性都有非常大的差異性。一個解決的方法是讓網路服務對這些情境（context）上的差異能充份認知（aware），並根據情境來調整運轉狀態。我們稱這類運算方式為情境認知運算（context-aware computing），而情境認知運算環境則支援情境認知應用的開發與運作，其中一個重要的元件就是情境服務（context service）。
在這篇論文裡，我們介紹一個情境伺服器（context server）的設計，採用集中式方法，有組織的提供情境服務給具有情境運算的應用。我們的情境伺服器收集的情境資料包含了感應器的資料、服務的屬性、使用者裝置的能力及使用者的喜好等。具有情境運算能力的應用可以透過我們的情境伺服器，獲得所需的情境資料，來調整他們的運轉狀態。

在論文的最後，我們展示了我們情境伺服器的應用。該應用利用情境伺服器與JINI Lookup Server提供情境資訊給普及計算環境中的服務。

Today, more and more devices are equipped with networking capabilities. When these devices are used to access network services, there are diversity and heterogeneity issues in terms of user preferences, device capabilities and network characteristics. To tackle these issues, many services are developed to be context-aware and adapt their behavior according to the environment. For facilitating the development of context-aware applications, one essential component is a comprehensive context service.
This thesis introduces a context server using a centralized approach to systematically supporting context service for context-aware applications. Our context server collects context information including sensor data, service attributes, client device capabilities and user preferences. Through our context server, context-aware applications can acquire needed contexts to adapt their behaviors.

As an illustration of the use of our context server, a system architecture for supporting pervasive computing is introduced. We will show how our context server cooperates with the JINI Lookup server to support context-aware and pervasive services.

[1] J. Burrell, P. Treadwell, and G. K. Gay. “Designing for Context: Usability in a Ubiquitous Environment.” In Proceedings of the ACM Conference on Universal Usability, November 2000.
[2] G. Chen and D. Kotz. “A Survey of Context-Aware Mobile Computing Research.” Technical Report, TR2000-381, Department of Computer Science, Dartmouth College.
http://www.cs.tut.fi/~tukar/Ubiquitous.pdf
[3] A. K. Dey. Providing Architectural Support for Building Context-Aware Applications. Ph.D. Thesis, Georgia Institute of Technology, December 2000.
[4] S. Duri, A. Cole, J. Munson, and J. Christensen. “An Approach to Providing a Seamless End-User Experience for Location-Aware Applications.” In Proceedings of the First ACM International Workshop on Mobile Commerce, July 2001.
[5] B. Guruduth, B. James, G. Eugene, M. Jonathan, S. Jeremy, and Z. Deborra. “Challenges: An Application Model for Pervasive Computing.” In Proceeding of the Sixth Annual ACM/IEEE International Conference on Mobile Computing and Networking (Mobicom 2000), Boston, August, 2000.
[6] J. I. Hong and J.A. Landay. “An Infrastructure Approach to Context-Aware Computing.” Berkeley, CA 94720-1776, May 2001.
http://guir.berkeley.edu/projects/cfabric/pubs/context-essay-final.htm
[7] K. Mari. “Context-Aware Applications Survey.” Internetworking Seminar, Department of Computer Science, Heldinki University of Technology, April 2000,
http://www.hut.fi/~mkorkeaa/doc/context-aware.html
[8] W. Y. Ma, I. Bedner, G. Chang, A. Kuchinsky, and H. Zhang. “Cooltown: A Framework for Adaptive Content Delivery in Heterogeneous Network Environment.” In Proceedings of Conference on Multimedia computing and Networking, Jan 2000.
http://cooltown.hp.com/dev/wpapers/adcon/MMCN2000.asp
[9] A. Schmidt and K. V. Laerhoven. “How to Build Smart Applicances?” In IEEE Personal Communications, page 66-71, August 2001.
[10] B. N. Schilit, M. M. Theimer, and B. B. Welch. “Customizing Mobile Applications.” In Proceedings of USENIX Mobile & Location-Independent Computing Symposium, page 129-138, Cambridge, Massachusetts, August 1993.
[11] D. Salber, A.K. Dey, G.D. Abowd. “The Context Toolkit: Aiding the Development of Context-Enabled Applications.” In Proceedings of CHI’99, May 15-20, 1999.
[12] M. Samulowitz, F. Michahelles, and C. Linnhoff-Popien. “Adaptive Interaction for Enabling Pervasive Services.” In Proceedings of the Second ACM International Workshop on Data Engineering for Wireless and Mobile Access, May 20, 2001, Santa Barbara, California.
[13] M. Satyanarayanan. “Pervasive Computing: Vision and Challenges.” In IEEE Personal Communications, page 10-17, August 2001.
[14] W3C Composite Capability/Preference Profiles (CC/PP): A User Side Framework for Content Negotiation.
http://www.w3.org/TR/1999/NOTE-CCPP-19990727/
[15] JINI: http://www.jini.org/
[16] Universal Plug and Play (UPnP): http://www.upnp.org/
[17] Salutation Architectures: http://www.salutation.org/
[18] Sun Microsystems, Inc. RMI: Java Remote Method Invocation, Version 1.3.1, May 2001.