GIS System Architecture Evolution
GIS implementations grew in size and complexity throughout the 1990s.
Organizational GIS Evolution
GIS started on the user desktops and evolved to support GIS workgroup operations with department-level file servers. A majority of the GIS community is currently supported by department-level GIS operations. Figure 2a-1 provides an overview of department-level GIS architecture.
As GIS evolved within a typical organization, several departments had local GIS operations that required data resources from other departments. The organization's wide area network (WAN) became a way of sharing data between department servers. Data standardization and integrity issues surfaced within the organization since data was developed and managed from different department-level sources.
The initial Spatial Database Engine (ArcSDE) release in the mid 1990s supported the first GIS enterprise data warehouse operations, and many organizations shared GIS data resources from a central ArcSDE data warehouse. GIS responsibilities were assigned within IT departments to consolidate enterprise-wide GIS data and establish common data standards across the organization. The enterprise data warehouse provided a reliable shared GIS data source for departments throughout the organization. This was a very common migration path taken by most local government GIS operations.
Figure 2-3 provides an overview of the organizational architecture alternatives.
The electric and gas utilities started using GIS in the early 1990s to support management of their power distribution facilities. Most implementations were supported by a central database. Remote users were supported with terminal access to application compute servers (terminal servers) located in the central computer facility with the GIS database.
Many organizations today are moving their geospatial data from department file-based GIS database environments to a common central enterprise geodatabase and providing terminal client access to centrally managed server environments. Departments retain responsibility for their data resources, updating and maintaining data through terminal access to central ArcGIS Desktop applications. The central IT computer center supports the general administration tasks of data backups, operating system upgrades, platform administration, and so forth. Users throughout the organization enjoy browser access to published Web services over the intranet. The complexity and sophistication of the geodatabase for central administration and support make centralized servers the most productive alternative for most organizations.
Community GIS Evolution
Year 2000 introduced a growing Internet awareness, demonstrating the tremendous value of sharing information between organizations and nations. Internet access was extended from the workplace to the home, rapidly expanding the user community. Figure 2-4 shows how communities and companies developed and deployed services to customers over the Internet. The Internet provided opportunities for organizations to share data and services between organizations. Users had access to data and services from a multitude of organizations through the Internet.
ESRI introduced the Geography Network, providing a metadata search engine that published information about GIS data services and provided direct Internet links between the ArcGIS Desktop application and the data or service provider. ArcIMS introduced a way for organizations throughout the world to share GIS data and services. The Geography Network established a framework to bring GIS data and services together, supporting a rapidly expanding infrastructure of worldwide communities sharing information about the world we all live in. Promotion of data standards and improved data collection technologies unlock enormous possibilities for sharing geospatial information and help us better understand and improve our world.
GIS data resources are expanding exponentially. In the 1990s, GIS data servers seldom required a database that was more than 25 to 50 gigabytes in size. Today it is common for organizations to operate geodatabase servers supporting several terabytes to petabytes of GIS data (one petabyte is equal to eight quadrillion bits of data).
State-level agencies are consolidating data to support municipalities and commercial activities throughout their states. National agencies are consolidating data to support their user requirements and sharing data between state and national communities. Community-level data marts are being established to consolidate GIS data resources and support Internet data sharing to organizations throughout county and state regional areas.
Many organizations are outsourcing their IT operations to commercial Internet service providers (ISPs). Application service providers (ASPs) support organizations with IT administration, providing opportunities for smaller organizations to take advantage of high-end GIS database and application solutions to support their business needs. State governments are hosting applications and data for smaller municipalities throughout their states so the smaller communities can take advantage of GIS technology to support their local operations.
Regional geography network sites support sharing data throughout the region and within large state and federal agencies. ArcIMS software provides a metadata search engine that can be used by organizations to share their data and support their community operations. Cities can establish metadata sites to promote local commercial and public interests. States can consolidate metadata search engines for sharing data and services with municipalities throughout the state. Law enforcement can establish search engines to support national datasets. Businesses can establish metadata search engines to support distributed operational environments. Web services support community data sharing and integrated workflows.
Deployment of ArcGIS Server with ArcGIS 9 expanded Web services technology to include geoprocessing and a broad range of service-oriented Web operations. GIS technology, in conjunction with Web standards and open systems architecture, has opened new opportunities for more improved business operations. As GIS data and services are shared among a growing number of organizations and technology provides real-time access to geographic information products, GIS becomes an integral part of community operations. GIS is rapidly expanding as a primary technology for understanding our world and related geospatial business opportunities. ArcGIS 9.3 opens GIS to enable an Internet technology revolution, new opportunities for business and communities alike through GIS services deployed on ESRI, Google, and Microsoft geospatial Web 2.0 platform environments.