Evolving Computing Architectures

The notion of GIS as a closed, proprietary system is no longer true. Geographic information is now widely distributed on the Web and routinely integrated into thousands of applications and services. The ArcGIS platform conforms to open standards and enterprise IT frameworks so users can incorporate GIS in any application, on a variety of computing and mobile devices, and use geographic information accessed from databases and Web services kept in almost any format.

Historically, client/server GIS applications that focused on data compilation and application projects have proven invaluable. With nearly 200,000 organizations worldwide using GIS in this way, this model has been so successful that many think of GIS only in this context. As other frameworks for GIS emerge, this will continue to be a vital strategy for using GIS and will probably remain the way GIS is most often implemented.

Client/Server GIS applications have proven invaluable and will continue to be an important implementation strategy.

However, GIS is used not only in the familiar client/server setting but also in centralized database management system (DBMS) environments that support multiple GIS users; in federated GIS networks of many distributed, heterogeneous GIS computing nodes; and in services-oriented architectures that use Web services. ArcGIS is engineered to support GIS use in each of these settings.

In the 1990s, GIS users began exploiting relational DBMS for building centralized information systems. Information was centrally managed and maintained using relational DBMS technology and accessed and edited by multiple users. This enterprise model, widely implemented in the public and private sectors, takes advantage of the robust data management capabilities afforded by relational database technology. It is and will remain a viable framework for GIS.

Central GIS takes advantage of the shared data management capabilities of DBMS technology.

Some GIS users need more than centralized systems for information sharing and collaboration. Recently, users have begun using GIS Web services for data sharing and Web publishing. Many user communities have established formal frameworks and participate in National and Global Spatial Data Infrastructures (NSDIs and GSDIs). These loose federations share GIS content and processing logic through GIS portals on the Web.

The need for greater collaboration has led to the growth of federated GIS.

Federated GIS is based on a distributed collection of GIS nodes that share and use each other's geographic information and services. Catalog portals provide access through a registry of available geographic information services and data sets. GIS users register their information services with the portal where other users can search for and discover available information. Each catalog entry contains a URL or access location for the registered information sets and services, enabling information from multiple users to be combined across the Web through the use of Web services.

A new trend is now underway to integrate heterogeneous application logic using services-based architectures developed originally for Web computing. This concept is referred to as a Services-Oriented Architecture (SOA) and will be used to integrate existing information systems in order to automate business practices, workflows, and information flows both within and across organizations. SOA was developed by IBM, Microsoft, and other leading IT industry organizations to support the building of applications that integrate existing computing technologies into solutions-based systems. GIS will be a key part of these implementations.

For example, using an SOA, a utility could assemble a trouble call system that integrates its existing customer database, command and control system, and fleet management system with a GIS server to locate an affected customer based on a phone number. The system would then find the affected service, perform network tracing and analysis, identify the potential remedy and, finally, route the closest service technicians to the proper location with detailed instructions on the work to be performed.

ArcGIS uses IT and Web services interfaces for managing and exploiting spatial information using messaging. In SOAs, GIS and other IT services are delivered via the same standards-based Web services and messaging protocols, such as XML and Simple Object Access Protocol (SOAP), used in mainstream business and enterprise computing frameworks.

GIS services are delivered via the same standards-based Web services protocols (e.g., XML and SOAP) used in mainstream business and enterprise computing frameworks that incorporate enterprise resource planning (ERP), customer relationship management (CRM), and supply chain management (SCM) systems.