普及運算的目的是讓使用者能夠隨時隨地使用在週遭環境中的運算資源完成他們的工作，因此，如何去部署以及搜尋這些運算資源是一個很大的問題。服務搜尋可以解決上述的問題，這個機制可以讓服務提供者發佈他們的服務，也可以讓使用者查詢所需的服務。
在本論文裡，我們為具有階層式特性的環境，如大樓，設計與實作了一個階層式服務搜尋系統，我們將討論為何階層式服務搜尋系統適用於這樣的環境。我們的系統有幾樣特點，首先，可以讓使用者依據自身的位置與服務的位置去查詢，第二，透過收集使用者的資料以及服務搜尋服務之間的合作，可以支援使用者在環境中漫遊。我們設計數個實驗去分析系統的效能，並且建構了數個應用程式來展示如何利用我們的系統提供服務搜尋。

The main purpose of pervasive computing is to allow people to use computing resources embedded in our surroundings to complete their tasks effortlessly at any time, anywhere. How to deploy and find the computing resources in our environment is a big problem. Service discovery solves the problem by letting service providers publish their service and users discover their desired services through a discovery service. Most discovery services focus only on the environment they serve, but not the interoperation among different discovery services.
We design and implement a hierarchical service discovery system focusing on environments that have a hierarchical structure, such as a building. We discuss why the hierarchical service discovery system serves such environments well. Our system has several features. It can let users search for their desired services according to their location and the location of the services. Our system also supports user roaming in the environment. We evaluate the overhead of our system with several experiments. We also show some applications to demonstrate the use of our system.

[1] W. Adjie-Winoto, E. Schwartz, H. Balakrishnan, and J. Lilley. “The Design and Implementation of an Intentional Naming System”. Operation System Review 34(5): 186-201, Dec 1999.
[2] J. Barton, and T. Kindberg. “The Challenges and Opportunities of Integrating the Physical World and Networked Systems”. HPL Technical report HPL-2001-18, 2001.
[3] P. Castro*, B. Greenstein, R. Muntz, C. Bisdikian, P. Kermani, and M. Papadopouli. “Locating Application Data Across Service Discovery Domains”. Proc. of MobiCom, pp. 28-42, July 2001.
[4] S. Czerwinski, B. Zhao, T. Hodes, A. D. Joseph, and R. H. Katz, "An Architecture for a Secure Service Discovery Service", Proc. ACM/IEEE Int. Conf. Mobile Computing, Seattle, WA, August 1999.
[5] Java Media Framework API. http://java.sun.com/products/java-media/jmf/
[6] Java Remote Method Invocation. http://java.sun.com/products/jdk/rmi/.
[7] Jini Starter Toolkit 1.2. http://developer.java.sun.com/developer/products/jini/.
[8] “Jini Technology Architectural Overview”. January 1999.
http://wwws.sun.com/software/jini/whitepapers/architecture.html
[9] B. Pascoe. “Salutation Architectures and the Newly Defined Service Discovery Protocols from Microsoft and Sun”. Salutation Consortium, 1999. http://www.salutation.org/whitepaper/Jini-UPnP.PDF
[10] M. Santayarayanan. “Pervasive Computing: Vision and Challenges”. IEEE Personal Computing, 8, 4, pp. 10-17, August 2001.
[11] “UDDI Technical White paper”, September 6, 2002.
http://www.uddi.org/pubs/Iru_UDDI_Technical_White_Paper.doc.
[12] “Understanding Universal Plug and Play”, June, 2000.
http://www.upnp.org/download/UPNP_UnderstandingUPNP.doc.
[13] J. Veizades, E. Guttman, C. Perkins, S. Kaplan. “Service Location Protocol”, RFC 2165, July 1997.
[14] M. Weiser. "The Computer for the Twenty-First Century". Scientific American, pp. 94-10, September 1991.