In addition to development of custom GIS web applications, Azavea has been developing web services for the past few years. What exactly are web services? They are a standards-based way to provide software building blocks over a network. They are not complete web applications on their own. Rather, they are small pieces of capability that can be combined to build new applications. A web service is also sometimes called a Web API (Application Programming Interface).

One web service that Azavea developed and hosts is Cicero. Cicero is a legislative district locator, elected official database, and legislative mapping service that provides data on local, state, and national legislatures. It is being used to support political advocacy campaigns and data integration.

ESRI also offers a suite of web services known as ArcWeb Services that provides geocoding, spatial query, and map generation capabilities that can be integrated into any application with access to the web. Several of Azavea’s web applications use ArcWeb Services, including Delaware Valley Association for the Education of Young Children’s (DVAEYC) CONNECT Services. This application uses ArcWeb for routing and geocoding. The key advantage is that the service provider (ESRI) takes responsibility for providing up-to-date street data, and we can focus on how we want the application to use the data instead of managing it ourselves.

Web services can also be chained together so that one building block is used by another to provide a new capability. For example, in Cicero, we use ArcWeb Services for locating addresses, but then we use the Cicero data for looking up the legislative districts, creating maps or finding data about legislators for the location. When web services are linked together like this into a more complex system, it is sometimes known as a Service-Oriented Architecture (SOA).

Web services are a fundamental part of the Web 2.0 revolution that focuses on making data open and easily sharable. There are several web sites that facilitate working with web services. Programmable Web is sort of like a phone book for public web API’s. OpenKapow enables users to develop their own web services that consist of sequences of actions one would take on a web site to view data or perform an activity. And Yahoo! Pipes enables users to combine sequences of RSS feeds into customized data streams.