The Programming Consultant Newsletter

ntroduction to OGC WMS and WFS

OK, that's a lot of acronyms. OGC is the Open Geospatial Consortium. They're a group that creates voluntary standards for geospatial and location based services. WMS stands for Web Map Service and specifies a standard for sharing images of geospatial information over the Internet through three extended URL operations – GetCapabilities, GetMap, and GetFeatureInfo. WFS stands for Web Feature Service, which is similar to WMS but rather than an image of geospatial data it serves geospatial data directly.

WMS and WFS are open standards, meaning they are publicly available specifications for achieving a specific task. By allowing anyone to obtain and implement the standard, they increase compatibility between various software components. In other words, it shouldn't matter what software you use – ESRI, GRASS, AutoCAD, MapInfo, etc. - if it supports the standard, you will be able to use the software to view and manipulate the data.

Why is this important? Data sharing, whether inter-departmental, inter-organizational, or extra-organizational (i.e. an external public or private agency), has long been a bugaboo in our field. SDE servers are nice, but they're very expensive and limited by internal network access. They're also proprietary solutions – only one brand of software will work, which can be especially limiting when trying to share data to other non-Mecklenburg agencies. Open standards like WMS and WFS will in all likelihood replace SDE and file servers as the primary means we share geospatial information.

Next month I'll show you how to be a WMS client and a server. In the mean time, check out NC OneMap. It uses OGC standards to pull data together from a number of different sources across the state.