Scalable and Extensible Infrastructures for Distributing Interoperable Geographic Information Services on the Internet by NADINE S. ALAMEH B.E., Computer and Communication Engineering, American University of Beirut (1994) M.S., Civil and Environmental Engineering, Massachusetts Institute of Technology (1997) M.C.P., Urban Studies and Planning, Massachusetts Institute of Technology (1997) Submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer and Information Systems Engineering at the ENG MASSACHUSETTS INSTITUTE OF TECHNOLOGY MASSACHUSETTS INSTITUTE OF TECHNOLOGY February 2001 FEB 2 2 2001 @ Nadine Alameh, 2001. All Rights Reserved. LIBRARIES The author hereby grants to MIT permission to reproduce and distribute publicly paper ana efe= tronic copies of this document in whole or in part, and to grants others the right to do so. Author ................... .......- , . .. ..., t . .. ........................... Department of Civiand Environmental Engineering January 19, 2001 C ertified by ........................................... 7 .,-a Ferreira Professor of Urban Planning and Operations Research Thesis Supervisor ii -.- I C ertified b y ...................................... .... .,.................................................... S John Williams Professor Civil and Environmental Engineering Thesis Reader Accepted by I. "."................... Oral Buyukozturk Chairman, Departmental Committee on Graduate Students Scalable and Extensible Infrastructures for Distributing Interoperable Geographic Information Services on the Internet by Nadine S. Alameh Submitted to the Department of Civil and Environmental Engineering on January 19, 2001, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer and Information Systems Engineering Abstract The explosive growth in Internet-powered services has fueled the quest for finding new killer Internet-based applications. This quest has often led to applications based on Geographic Informa- tion Systems (GIS), especially in the emerging field of the Mobile Internet. Unfortunately, the tra- ditional GIS model falls short of accommodating the requirements and needs of the Internet environment. A more flexible GIS model is required to support the growing need for sharing increasingly avail- able yet distributed geographic data, and for facilitating the integration of GIS with other informa- tion systems. Such a model will be especially beneficial for scientific research and engineering modeling as well as state and federal government settings, where tightly coupled hierarchical sys- tems are unlikely to have the desired breadth and flexibility. This next generation flexible GIS model is seen to deliver GIS functionalities as independently-provided, yet interoperable, services over the Internet. Such services can then be dynamically chained to construct customized applica- tions. The goal of this thesis is to develop a framework for building a scalable and extensible infrastruc- ture that can support and facilitate the dynamic chaining of distributed services. Towards that goal, the thesis evaluates and contrasts a set of alternative architectures. In doing so, it identifies the key elements and players, and focuses on issues pertaining to error handling, back-tracing of data and services in transactions, as well as service discovery and network management. A detailed analysis of a typical use case shows that a federated architecture is the most promising in terms of meeting the scalability, extensibility and flexibility requirements of the infrastructure. In this context, the thesis stresses the necessity of service and catalog interoperability, the need for GIS metadata standards which comply with general IT standards, and the usefulness of XML in defining extensible GIS data exchange standards. The thesis argues that the sustainability of a dis- tributed infrastructure also depends on successful organizational partnerships, scalable schemes for network management, as well as technical enhancements of GIS services in terms of data streaming techniques and effective compression standards for GIS data on the Internet. Thesis Supervisor: Joseph Ferreira Title: Professor of Urban Planning and Operations Research Acknowledgments Thank God it's finally over! The Ph.D. process has been such an extremely demanding experience, sometimes more on the emotional level than the intellectual one. And truth be told, I could never have gone through it without the help and support of several people around me. I would like to thank Professor J. Ferreira, my research advisor for six years, for his support and guidance throughout this study and my stay at MIT. He has been a great inspiration. I have gained a lot from his expertise, his enthusiasm and his interest in how technologies can shape our lives. My sincere thanks also go to Professor K. Amaratunga for his patience and his time, and to Profes- sor J. Williams for his help throughout my graduate studies. My most sincere thanks also go to Cynthia Stewart for her patience and support, especially during the last few months. I consider myself very lucky to have had John Evans as my office-mate for the last three years. I thank him for his help, sense of humor and most of all his friendship. Thanks for having the patience to listen to me nagging about this thesis on a daily basis! Many special thanks to the CRL staff for making me feel right at home, especially Tom Grayson who always knew how to cheer me up! And of course, the PSS alums for their support and friendship, especially Raj Singh, Matt Gen- tile, and Ayman Ismail. Throughout my years at MIT, I have made very special friends who have made my stay here very enjoyable! I thank them dearly, especially Fadi Karameh, Saad Mneimneh and Mazen Wehbeh from the lebanese gang, and Petros Komodoros, Salal Humair and Terry Vendlins from the 1.00 gang! I would also like to thank my Jazzercise buddies and instructors for making me look forward to that one energy-boosting hour every day! I can never thank enough my husband and best friend, Hisham Kassab, for his love and patience, his endless attempts at motivating me and for accommodating my weird mood swings! At some level, this experience has tremendously strengthened our relationship and I am thankful for that. I feel very lucky to have someone as nice, so caring and so smart by my side, now and in the future. Finally, I thank my family for the unconditional support they provided me! I especially thank my mother for her endless prayers and her daily support whether on the phone or through emails. My thanks to my sister, my "baby" and great friend Rola (aka Roro), for enriching my life in ways I could never describe. And for my brother Rani for his support and encouragement and for teaching me so much about patience, perseverance and hope. I dedicate this thesis to him. Table of Contents 1 Introduction ............................................................................................................................ 9 1.1 Overview ....................................................................................................................... 9 1.2 M otivation ................................................................................................................... 10 * 1.2.1 Benefits of A D istributed GIS Infrastructure............................................. 11 * 1.2.2 The Significance of Scalability and Interoperability .................................. 13 * 1.2.3 The Sources of Com plexity ...................................................................... 15 1.3 Objectives and Contributions .................................................................................. 18 1.4 Research M ethodology........................................................................................... 19 * 1.4.1 Looking at Existing Technologies and Efforts .......................................... 20 * 1.4.2 Learning by D oing: A Prototyping Experim ent......................................... 20 * 1.4.3 Identifying Basic Architectural Elements and Setups ............................... 20 1.5 Thesis Organization................................................................................................ 21 2 Background...........................................................................................................................22 2.1 The Evolution of GIS ............................................................................................. 23 - 2.1.1 Legacy GIS System s .................................................................................. 23 * 2.1.2 Influences of Em erging Technologies ...................................................... 23 * 2.1.3 A vailability of Spatial D ata ...................................................................... 25 - 2.1.4 Im pact of the Internet................................................................................ 26 * 2.1.5 Em erging Role of GIS in Today's Enterprises ........................................... 26 - 2.1.6 M obile and W ireless Technologies........................................................... 27 2.2 Interoperability and Standards ............................................................................... 27 * 2.2.1 Interoperability........................................................................................... 28 * 2.2.2 Standards...................................................................................................