Although initiatives like the Geography Network and the advent of mobile GIS applications such as ArcPad will garner significant long-term attention from the ESRI user community, perhaps the most immediate impact for users leaving the 2000 ESRI User Conference is the announcement of the unification of the ESRI product line, called ArcGIS. Pieces of ArcGIS as envisioned by ESRI already exist today and are depicted in the figure below.
Simplified ArcGIS Product Schema
At a high level, the ArcGIS family of products aims to separate the strong coupling that has traditionally existed between spatial data and the software that operates on that data. In the past, the only alternative to spatial data storage was file-based. This approach suffered from severe scalability problems because users were required to invest large amounts of resources to ensure that data was not accidentally corrupted during the course of daily editing and manipulation. Furthermore, the existing cache of spatial data could not be easily integrated with other non-spatial data stored in large-scale, enterprise relational databases. Today, the alternative to file-based GIS is to store spatial data in a database management system (DBMS), such as ArcSDE, Oracle, Informix, DB2, or SQL Server, and rely on the software to provide varying levels of interaction and functionality. In the absence of the use of ArcSDE as the primary database store, there is an additional layer of technology provided at no cost by ESRI, ArcSDE database gateway, that mediates between the database and the client product. From the end-user’s perspective there are several clients available for interacting with the data in the database. Users who are only interested in simple feature display may settle for a thin browser-based HTML client delivered by an ArcIMS server. For data interaction that requires, among other things, complex feature selection or high-quality cartographic production, ArcView is the client of choice. Finally, the ArcInfo client is for the power user who must maintain and develop new spatial databases. In essence, each user accesses the same data using a different front-end application, ArcIMS, ArcView, and ArcInfo, simplifying the task of keeping the organization’s data current and correct.
In comparison to database technology, the development of component technology to facilitate the interoperabilty of software has been a relatively recent phenomenon. ESRI has taken advantage of this development to craft a robust suite of software components, known as ArcObjects, centered around the functionality that had been present in their two main-line products, ArcView and Arc/INFO. Despite the initial high cost of re-architecturing the ESRI product line, component technology presents a significant advantage to the software company because products can be developed and sold at incremental aggregate units of functionality not possible using other means. For the end-user, this means that ESRI can offer a broader range of products, from simple data viewers to complex analytical engines, which are all built upon the same foundation of compiled binary objects. For the developer, this means that the entire ESRI product line is exposed by the same set of application programming interfaces (API). The scope of the project dictates the depth to which the APIs must be exploited, as well as the added cost of licensing the increasingly more functional components.
The most basic non browser-based ArcGIS client is ArcView 8.1. Unlike the current release of ArcView, version 3.x, the ArcView 8 product line is built using the same COM (Component Object Model) components, ArcObjects, used to build the recently released ArcInfo 8. What this means for the user is that the project, view, and layout documents in ArcView are being replaced by the ArcCatalog and ArcMap user interfaces already present in ArcInfo 8. This change benefits the user because there is no longer a distinction between users with the ability to use the command-line version of workstation Arc/INFO and the point-and-click interface of ArcView. Instead, the rich functionality available from the command-line has migrated into the widgets and controls present in ArcCatalog and ArcMap. This will make it easier for those who learn ArcView 8.1 to translate their skills to ArcInfo 8.1. In addition, users of ArcView 3.x should not despair about losing their valuable project files (.apr). One of the feature demonstrations of ArcMap given during the first day of the conference included an ArcView project import utility distributed with ArcInfo and ArcView 8.1. The most significant change to the ArcInfo product line is the creation of two versions: ArcInfo Editor and ArcInfo Professional. The ArcInfo Editor product is new and includes the same functionality from ArcMap and ArcCatalog that is included with ArcView 8.1. In addition to the ability to edit shapefiles that is included with the current versions of ArcView, ArcInfo Editor also provides the ability to edit coverages and vector geodatabases stored in ArcSDE, Oracle, Informix, DB2, or SQL Server. ArcInfo Professional is the most sophisticated product in the ArcGIS product line and provides the full complement of functionality available from the ArcCatalog, ArcMap, and ArcToolbox applications as well as the traditional command-line interface familiar to users of Arc/INFO.
In summary, this article has described the new ArcGIS product family which incorporates advances in the areas of database, software component, and user interface technology. The weaknesses of file-based GIS for anything other than single projects has long been recognized and is seriously addressed by the added support for DBMS-based GIS in the ArcGIS product line. The array of choices now available, ArcIMS, ArcView 8.1, and ArcInfo 8, would not be possible were it not for the ability to package and sell software in incremental aggregate units constructed from component technology. Finally, the single unified user-interface that is common to all the non-browser based clients, ArcView 8.1 and ArcInfo, will substantially improve the ability of ESRI users to translate skills learned in one software product to the other products. Whatever your application, local government, facilities, transportation, or conservation, these developments will help you.
Realizing the Benefits of an N-Tiered Enterprise GIS
This year’s ESRI User Conference is an especially significant event in the history of the GIS industry because of several concurrent developments in technology. One of these, the advent of the N-tiered enterprise GIS, is discussed in this article.
The Geography Network
The Geography Network is the newly unveiled effort by ESRI to bring GIS data and services to the Internet.
By Marco Morais