URL to USL or web enabled GIS

Overview
The emergence of distributed technologies known as CORBA or EJB, Universal Database Servers such as Oracle8I or DB2 Universal Server and the Internet has enabled many new and exciting end-user experiences over the WWW. Examples of such are video-on-demand, realaudio, music-on-demand, and the many flavors of e-commerce. The birth of the WWW came about as a need for researchers around the world to share information in a way that eliminated the barriers of space and time. The next generation of the WWW now includes e-commerce and the “dot com” businesses, such as Amazon.com. In very little time the amount of information accessible from a simple browser has grown exponentially to the point now that the search engines have trouble indexing everything in a timely manner and keeping the information up-todate. Just as published directories, such as yellow pages, became difficult to use the more information they had, so has the information on the WWW. Try a simple example, look for the five Italian restaurants closest to where you currently are, this conference hall, so that you can make a reservation for this evening. Now most of you will not be familiar with the locale so you turn to the yellow pages, either hard copy or published on-line and look for the listings of Italian restaurants. Maybe there are 20 or more entries, maybe they are all lumped together under restaurants, but for sure they will not be sorted relative to where you currently are. What this paper is going to explore is the possibility that we can add to the WWW the very thing that it was initially designed to eliminate that is space and time.

OpenGIS Corba specfication and web based GIS
The OpenGIS CORBA Specification [1] states:

“ The purpose of OpenGIS CORBA specification is to provide interfaces to allow GIS software engineers to develop applications that expose functionality required to access and manipulate geospatial information comprising features with ‘simple’ geometry using OMG’s CORBA technology. CORBA (Common Object Request Broker Architecture) provides a specification for the object-oriented distributed systems in a language, operating system, platform and vendor independent way. CORBA consists of a core implemented by the various commercially available ORBs (Object Request Brokers) and a number of specified object services and application facilities (CORBAservices and CORBAfacilities). Facilities may be horizontal (provide services of a general nature to applications such as a graphic user interface or task management) or vertical (provide services targeted to a particular industry or domain). It is envisaged that this specification will become a candidate for inclusion in the OMG’s work as a vertical CORBAfacility covering geospatial information management.”

In the past three years web based mapping has progressed from being simply a dumb raster image of a map to where we now have three-tier architectures being implemented using AutoDesk’s Mapguide Author, Server and Viewer tools [2]. This evolution of web based mapping has been clearly articulated in the articles by W. Frederick Limp [3], [4] and is not covered further in this paper. Although such an evolution was inevitable, vendors of GIS software have to have offer their existing customers some capabilities for their intranets and the visual aspect of the web makes maps appealing, it is not the same as spatially enabling the WWW or providing the location aspect to e-commerce.

In a recent article in Scientific American [5], David Clark states:
“Within a decade, most people in developed countries will have access to Internet connections that are tens if not hundreds of times faster than the ones in common use today. Although that development may not sound exactly earth-shaking, it will in fact herald an entirely new stage in the evolution of that global network. … Those high-speed connections to the home--whether they take the physical form of a telephone wire, a cable television line or a satellite link--will give rise to an entirely new set of applications. “

Many other technologies have emerged in the last few years that can be considered ancillary to the WWW but which when taken together are redefining software architectures today in much the same way client/server and RDBMS transformed them in the 80’s and early 90s. These technologies are Java, web browsers, CORBA, EJB, DCOM, and universal database servers, such as Oracle8. In two white papers [6], [7], the author has discussed at great length the emergence of these technologies. In particular these papers discuss how they can enable not only the storage of spatial data in a database but also how they can help to deliver the “Simple Features” as defined by the OGC [1].

Industry uptake of these technologies has been varied, an article in Utilities it [8] suggests that: “if spatial data technologies are to become the next de-facto standard in utility GIS, their next generation must address the limitations of current spatial engine products.” Others [9] see that it is time to move these new spatial engines into the heart of the enterprise to spatially enable legacy applications and datastores.

If we were to build a web-enabled GIS, what would it look like using these new technologies? The following graphic, titled “Web Centric Architecture for Distributed GIS” shows that it could have the look and feel of an n-tiered architecture [10], Clients/Web-Servers/Distributed- Components/Data-Stores.