Scalable and extensible infrastructures for distributing interoperable Geographic Information Services on the Internet

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 Information Systems (GIS), especially in the emerging field of the Mobile Internet. Unfortunately, the traditional 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 available yet distributed geographic data, and for facilitating the integration of GIS with other information 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 systems 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 applications. The goal of this thesis is to develop a framework for building a scalable and extensible infrastructure 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 distributed 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.