Traditional Web-based GIS tools allow governments to publish interactive mapping applications on a Web site, allowing citizens to use the maps for their own purposes while simultaneously providing a way for agencies and jurisdictions to share geographic data.

Web-based systems are popular because users can access them from any computer with an Internet browser. They are also easily and inexpensively maintained since all the software resides on a central server -- IT staff needn't visit users' machines to troubleshoot software problems or install upgrades.

Though the public sector uses Web-based GIS in many ways, the approach is not without drawbacks.

One problem is that Web-based GIS applications aren't as powerful or versatile as the systems GIS professionals run on their desktops.

Historically software developers took a small number of desktop GIS functions -- mapping, geocoding and point-to-point routing -- and turned them into an Internet service designed with an Internet-based architecture, said David Maguire, director of products and international at GIS developer ESRI in Redlands, Calif.

"It fit nicely into the Internet, but it didn't have all the functional capabilities high-end GIS users had come to expect and require," Maguire said.

Enterprise GIS Servers

Maguire said ESRI saw a market for an alternative to both desktop-based GIS solutions and the less-functional, Web-based GIS applications created with tools such as its own ArcIMS.

That alternative is what ESRI calls an enterprise geographic information server (EGIS). ESRI debuted its first EGIS product, ArcGIS Server, last year. As with any new product offering, it's too early to tell whether the EGIS product line (or other competing efforts by GIS vendors) will gain a foothold in the government marketplace.

One thing is clear: Many governments and government agencies realize the value of pursuing an enterprise GIS architecture. In part, it allows governments to make better use of GIS data and investments into hardware and GIS software.

Perhaps more importantly, an enterprise GIS architecture could create an environment more conducive to information sharing.

GIS Utility

Oregon's Geospatial Enterprise Office (GEO) is pursuing an enterprise GIS architecture to improve information sharing, and plans to implement ArcGIS server to support a "GIS utility" the state is currently developing.

The utility project is in its early stages, said Cy Smith, Oregon's statewide GIS coordinator. Under the first portion of the three-part development program, Oregon is assembling data sets -- for use by state, local, federal and tribal agencies in Oregon -- covering 14 "themes," such as transportation, hydrography, elevation, tax lots and administrative boundaries.

The second component is creating a central architecture allowing the state to deliver GIS data and functions over the Web. Oregon already uses ESRI's ArcIMS and ArcSDE products with an Oracle database manager to distribute data and maps via a Web server.

"We need a central enterprise server that has some tools that will allow us to make the data more accessible in real time," Smith said. "Right now, our ArcIMS application is very simple. You can view the data. You can zoom around and do some simple queries, but you're not really making full use of the data -- as you would in desktop GIS software with full-blown functionality."

For the third component of the program, Oregon will create an engine allowing GIS applications to draw data from multiple sources -- some of it housed in a central server, and some housed in servers owned by agencies that need to maintain their own data.

Data that falls under the transportation theme -- information on street center lines, address ranges, highway attributes, etc. -- might reside with any number of agencies at different levels of government, Smith said, and Oregon's data clearing-house combined with the GIS utility

Merrill Douglas  |  Contributing Writer