ArcIMS and Open Source Software Help Town Go Online
Continued...
Web Site From Scratch
The next step was choosing the data format and developing the Web site. ArcIMS cannot read geodatabase files directly, and West Springfield did not have ArcSDE. Only the layers needed for the system were exported as shapefiles and saved on the server. This also improved performance because ArcIMS was reading the shapefiles off a local drive rather than over a network connection.
To accommodate members of the public with limited computer experience and slow Internet connections, the author developed a simple Web site that is small in size and has easy-to-use search options. Although the wizard-based AIMS Designer could have been used to create a Web site instantly, this Web site is a general purpose one that is huge. This general site is referred to as the "kitchen sink" Web site by Esri instructors as the author learned when he took training. In addition to its large size, only a small portion of the code would be useful for this project, and the Web site would not be able to search an external database.
Instead of using the wizard, the entire Web site was created from scratch using HTML, cascading style sheets (CSS), and JavaScript. Scripts were written, grouped in different files, and saved in a separate folder so they could be shared by different map services. It is notable that this Web site is about 35 KB as compared with the 450 KB Web site created by ArcIMS Designer. The custom site downloads and refreshes more rapidly even with slow dial-up Internet connections. To reduce initial requests to the server and speed the download time when a user visits the site for the first time, a pregenerated map is passed to the client rather than having ArcIMS generate an image of the same initial town extent every time. This is one of many tricks the author learned from Esri training.
Linking With Tax Database
Searching the tax database and selecting a parcel using ArcIMS was the next, and biggest, hurdle. If ArcIMS could search the external database, it would have been easier. What made things more difficult was that Oracle was running on a Windows 2000 server and the Web server was on a Linux server, necessitating a cross platform solution.
While researching this solution, the author learned that JSP can be used on the Linux OS to search any relational database on Windows via Sun's JDBC and generate dynamic Web pages based on the database. Apache Tomcat, the official implementation of JSP technology, was already installed with J2SDK. Two JSPs were written and incorporated into the Web site to search the database and retrieve property information as well as PINs.
This information was used to send a request to the ArcIMS application server that generates the map for the selected parcel. These maps are generated in 8-bit PNG format at 500 x 500 pixels resolution. This smaller file size preserved sufficient image quality. The mapping portion of the site and JSPs were designed to communicate with each other so a parcel could be searched by address or PIN or by clicking on the map to get property information from the tax database.
Because a picture is worth a thousand words, these Web pages are now very lively. In VISION, photographs for each parcel are saved in JPEG format in a folder and paths are stored in the database on the Windows server. LinNeighborhood, another free Linux application, was used to mount the Windows shared folder containing pictures to Linux server. The JSP page uses that mounted drive to read JPEG files off the Windows server and passes them to the client via the Internet. A link that is changed dynamically based on the PIN opens the relevant pregenerated 11" x 17" tax map in PDF format so it can be printed to supply details such as parcel dimensions.
Looking Toward the Future
Parcel information is very important to most of West Springfield's departments for daily tasks. Staff members in these departments who need GIS all the time use ArcGIS 8.3 to access tax information. Those who don't need GIS constantly use the Web site to get property information. The site, available at gis.west-springfield.ma.us, has been up for several months and has already proved very useful for town employees, residents, and businesses. When the site was developed, provisions were made for future improvements. The town looks forward to making other GIS-related information, such as building permits data, available to the public using its ArcIMS site.
For more information, contact
Mohammed A. Hoque, GIS Coordinator
Town of West Springfield, Massachusetts
Tel.: 413-263-3070
E-mail: thoque@west-springfield.ma.us
Web: gis.west-springfield.ma.us
About the Author
Mohammed A. Hoque received bachelor's and master's degrees in urban planning with an emphasis on GIS in Bangladesh and the United States. He worked for years at the Surface Water Modelling Centre (SWMC) in Bangladesh on GIS analysis and GIS customization before moving to the United States for further education. He now works as the GIS coordinator for the town of West Springfield, Massachusetts.
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