Volume 26 • No 01 • 2003
ISSN 0742-468X • Since 1978
On-line Since 2000
Web Services and GIS
Just when you thought you had the web figured out, along comes another standard that promises to be the next killer app. The latest and greatest is the idea of something called Web Services.
The concept of Web services is relatively simply to understand. Business use information technology because it helps them function more efficiently. As the technology matured businesses began to exchange information electronically. With the advent of the Web, this idea of electronic information sharing became obvious, even as the requirements became more onerous. This need for information exchange brings in another need to make this information selectively visible and its visibility to be changed on the fly.
Imagine a world with telephones but no directory services, or television without channel and programming listings. The information would be there, but getting to it would be a nightmare. Now consider the world of information technology.
At first it was rather simple: each company had its own computer for its own use. Over time mergers and acquisitions and sheer growth made it necessary to share information among the central and remote locations. True the Internet did help this cross-communications, but often at the cost of security and exhaustive research to find the right data.
As developers continue to use the World Wide for business to business communication, a standards and interfaces are needed. The programmatic interfaces made available are referred to as Web Services. Web Services is based on the already existing and well-known HTTP protocol, and uses XML as the base language. This makes it a very developer-friendly service system. This is contrasted to other attempts at solving the B2B market such as RMI, COM, CORBA, EDI, and ebXML. However, most of these involve a whole learning curve. New technologies and languages have to be learned to implement these services.
A simple view of Web Services as it pertains to business is that it provides a means of communication between two remote systems, connected through the network of the Web Services. When a merger or acquisition takes place, vast sums of money are often spent to integrate the different computer systems. But, with Web Services technology companies don’t have to invest large sums of money developing software to bring the systems of the different companies together. By extending the business applications as Web Services, the information systems of different companies can be linked. Using simple SOAP (Simple Object Access Protocol) messages over the normal HTTP Web protocol then can access these business systems. For example, a utility requires transformers to be supplied when the material in stock reaches the threshold levels. These levels can be constantly monitored by the business system of a trusted supplier, and promptly replenished, without having to wait for a supervisor to notice it and generate a work order. The key is that the supplier’s system and the utility’s system are not the same, nor were they originally developed to do this task. Note also that the systems are “trusted” — a security concept meaning that both systems are secure and are authenticated to one another.
Web Services, as it is developing becomes more that another yellow pages directory, more than a standard, and more than a web page. If I had some data that I wanted to share with you, or to sell to you, I would create a Web Services compliant metadata and locate in the root directory of my web server. When you were in need of such data, you would seek this type of data, but would only need to look in the root directory of web services for the specific page that described the data. You would then see the data that was available, how to use it, etc., all on your web browser. Once you acquired the data, Web Services technology would then take over again to bind the data sets so you could share the information.
That is a very short introduction to Web Services.
For all the gory details, visit www.webservices.org, the site of WebServices Org.
Web Services and GIS
Recently, Tom Harrington of Applied Geographics (www.appgeo.com) told us about a recent project his company completed that used Web Services for GIS.
The Boston, Massachusetts company completed the development of a Web-services based online mapping capability for the Town of Plymouth, Massachusetts. The AGI application is a good example of applying Web Services to GIS: real-time data integration from a variety of sources in different locations. Three servers combine to present the information accessed by the Plymouth application — Tax Assessors data served by Patriot Properties, Orthophotography served by MassGIS, and Parcel, Zoning, Census, and Precinct GIS Data Layers served by AGI. The application is one of the first in the Commonwealth to utilize MassGIS’ new Web services that enable GIS data layers and orthophotography to be served directly from MassGIS to Internet applications.
“This Web-based application represents a milestone in AGI’s work to provide state-of-the-art Web GIS services that are tailored to the specific needs and situation of each municipality”, said Michael Terner, Executive Vice President of AGI, “Rather than creating a parallel mapping system, we provided a mapping solution that fits seamlessly with the Town’s existing investment in online property information retrieval. In addition, we are proud to be one of the first firms to put MassGIS Web services to work for the benefit of our municipal clients.”
Conclusion
Web Services is a technology to watch. End-users and developers are pushing it, always a good sign. There is still a long way to go, particularly in the area of security. Even with trusted relationships, it is hard to justify allowing a third party computer system behind your firewall. This is a problem that will be solved.
Some industry experts that I have spoken with suggest that until the security issue is solved Web Services will be used by companies internally to access data across the enterprise. This will give the developers time to improve the technology and close some of the security holes. Then in the next five years, we may begin to see Web Services as ubiquitous as the Web itself.
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