At Your Service: The Commonwealth of Massachussetts Embraces GIS Web Services

Say "MassGIS" in at any gathering of GIS professionals in Massachusetts and they think of one thing: data. But that's changing. MassGIS is rolling out new data delivery tools and a variety of geospatial Web services that take advantage of OpenGIS® Specifications to help maximize information sharing and delivery. As a result, in time, MassGIS may also be thought of as a provider of Web services that power the Commonwealth's agencies' and partners' map-enabled websites.

For years MassGIS, officially part of the Executive Office of Environmental Affairs has been the place to go for statewide data. Zoning, open space and orthophotos continue to be the most popular requests. In the early days of GIS, MassGIS distributed CDs of ESRI coverages. In time, those evolved into CDs of shape files coupled with a custom version of ArcView 3.x called the MassGIS Data Viewer. Until the beginning of 2003, downloading data tiles from the MassGIS website was the quickest and easiest way to access data, but it was still confusing and time consuming.

Starting in Spring 2003 MassGIS is rolling out its latest technology offering for data hungry citizens and professionals. At the same time, the organization is offering GIS Web services for use by the state's agencies, towns and partners. The move to a Web services framework began some two years ago with studies that identified key government functions that should be packaged as services. Among them were e-payment services, security services, customer relationship management services and spatial services.

MassGIS as GIS Data Distributor

As "keeper" of the Commonwealth's data, MassGIS quickly became busy with queries for digital data, as early as 1989. "One of the things we learned early on is that providing data, raw data, was not enough. It had to look nice and immediately provide information," says Jacqz. This realization inspired the ArcView-based GIS Data Viewer. The Data Viewer not only provided access to MassGIS data provided with the Data Viewer, but also provided the tools necessary to look at and make sense of this data. The Data Viewer provides two key functions beyond the basic GIS tools provided in ArcView. The first provided access to the MassGIS data, organized into a hierarchical tree structure. A second new feature allowed the user to immediately jump to the geographic extent of a particular town, city or other area of interest … functionality known as a gazetteer. Behind the scenes, the staff of MassGIS provided meta data, standard legends and well-defined scale dependencies - elements that helped make the application more accessible to casual and experienced users, alike.

As MassGIS moved that data to the Web in the mid-90's it was clear that the tree structure and the symbology from the Data Viewer needed to come along, too. The other challenge was managing hundreds of data layers in an online GIS. Said Jacqz, "we saw the Web as simply the next technology for data distribution. As Web services matured we realized we could make our data delivery less proprietary."

The challenge of creating the middleware to realize MassGIS' vision fell to Syncline, Inc. - a Boston-based firm specializing in Web-based GIS applications and Web services and a member of the Open GIS Consortium.

Building Services and Interoperability at the Same Time

Syncline realized the best way to tackle the idea of services was to follow both Web standards and OpenGIS® specifications. Together, these would provide an open, documented interface for both GIS and Web developers to work with the system. One of those developers would be Syncline itself. The company used Java to build some of the first real applications against the new services. The interactive nature of the products MassGIS needed demanded Java (over a thinner, HTML-based application), but as Aleda Freeman, a programmer at MassGIS, points out Syncline technical staff, like other developers, are free to use whatever language they feel is most appropriate.

To provide MassGIS with the required services, Syncline outlined a plan with four main services. Each service supports many different requests thus providing developers a list of a dozen odd service requests from which they can build their custom applications.

Drawing maps is the most basic service focuses. Syncline and MassGIS turned to the OGC's Web Map Service Interface Specification (WMS), which has been available since 1997. The WMS specification details how to ask a server for listings of what map data is available, how to ask the service to deliver that data as a picture, how to ask a service for information about a particular feature and how to ask for an extract of the raw data to be delivered. The queries are all delivered via a URL; the one above requests a particular area of map. Syncline built the specification into MassGIS' Web Mapping Service built on ESRI's ArcIMS. Then, the company built a client in Java to use the interface to ask the server for a list of data layers, to zoom in or out, and identify features. To an end user the browser client (below) doesn't look or act any differently than any other Web application. However, underneath, it's using the standard interfaces defined in the WMS Specification.

The second service, a Web Gazetteer Service, aims to link the name of a place, say a town like Winchester, with its geographic boundary. That's very useful for displaying the appropriate area of a map. This service draws on an OpenGIS draft specification, the Gazetteer Service Draft Specification and the OGC approved Filter Encoding Specification.

A geocoding service, basically a tool that given an address returns the x,y location of the point, was third on the list of required services. MassGIS selected MapInfo's MapMarker geocoder to power the service, but to keep things open, Syncline placed an OpenGIS Interface in front of it. In this case, Syncline implemented the Geocoder Draft Implementation Specification, which at some point will be approved by the OGC as part of a suite of interfaces developed in the OGC's Location Services initiative.

One other service, still under development, allows a user to add or edit a data point and its attributes in a database. The service relies on the Web Feature Service/Transaction Draft Interface Specification. MassGIS is prototyping an application using this interface for Massachusetts' Division of Capital Asset Management which will allow site managers to map and identify individual building footprints through a Web interface. A similar Web application for the Bureau of Waste Site Cleanup will allow private sector cleanup specialists (Licensed Site Professionals, LSPs) to capture x,y coordinates for hazardous material releases through a map window.

Josh Lieberman, Syncline's Vice President of Information Architecture, describes the company's addition to the server as the "interoperability" layer. This layer essentially presents standard interfaces to developers although they need not know exactly what's going on behind the scenes. For example if an application calls for geocoding an address, the programmer would simply follow the interface for geocoding, which basically involves sending specific XML code to the geocoding service. The service would then send an XML reply containing the geographic coordinates of the requested address, which the developer could parse and use.

Client Software: How Casual Users Tap Into MassGIS Resources

Syncline built the Web-based MassGIS Data Viewer to the organization's specifications as the next generation of its desktop counterpart. Syncline chose to develop the client using Java or, more specifically, as a Java Web Start application, because this technology best met the application requirements. The browser, sometimes referred to as "ArcExplorer on steroids," relies on a WMS to provide online maps for exploration or printing. But in addition to that functionality MassGIS wanted one more thing from the Data Viewer: the ability to act as the interface for data downloads.

Development Interface: How Developers Tap Into MassGIS Resources

State agency or municipal Software developers who want to use MassGIS' Web Services start with a 100-page document, the GIS Web Services Handbook, that describes all of the services and interfaces. >From the detailed notes and examples, Aleda Freeman, who authored the handbook says, "It's fairly easy to get started. However, the best way to create an application is to find one that looks similar to the one required and tweak it." After studying some samples, she was able to develop her first online application built against the services in a few weeks.

MassGIS has been developing a handful of applications to test the system even as it continues to add data layers to the Viewer. Some are rather simple, such as the "Shoreline Change Viewer" (left) which displays data about the extent of the state shoreline over time. Others are more complex such as an application to find a resident's legislative district. Visitors can search by town or city representative name (if there are multiple matches a list pops up to clarify the request further).

Issues and Challenges

While quite pleased with the success to date, both Jacqz and MacGaffey have questions that have yet to be answered. One issue is the need to manage those who have access to the services to be sure that throughput is high enough. Most likely, says Jacqz casual users will be granted free access to use the Java Data Viewer. Developers will require password access. Jacqz is concerned that some companies or individuals may want to access the services, then resell them. He feels that since developers will need to get access to the services, it will be relatively easy to monitor that type of behavior. As for examining the cost benefit of the decision to move to services, both Jacqz and McGaffey make it clear, it's fairly hard to pin down. They do note that by providing these robust services, state agencies can dramatically cut their costs in adding mapping tools. The other benefits are those that accrue from services that simply would not be available! Some benefits are not easily quantified, such as the goodwill created when a citizen can easily interact with the Web to find information. Jacqz points to the LSP application noted above. Using the forthcoming application to locate environmental incidents, LSPs can more quickly and accurately provide their reports.

Still, the general feeling of the MassGIS staff is one of "technology security." The organization, like many others, has made some difficult technology transitions over the years as software platforms, languages and capabilities changed. Now, with the spatial data and some key services independent from vendor specific implementations , Jacqz feels confident he's insulated his assets for the future. "The Web, he argues "is not going away, nor is Java. The Web and OpenGIS standards may be tweaked, and we may want to add more services, or change some, but that's much easier done today than any changes we've made in the past."