A Web Processing Service is little without a client. We have developed various clients ourselves in the past, but most of the projects have been discontinued. We developed a prototypical WPS client for ArcMap, however this was never deemed ready to be released. Another open source client we came across is the Quantum GIS WPS client. It works with several WPS implementations and also supports data streaming (see this post). Last year the Ordnance Survey of the U.K. approached us. They use WPS for web-based generalization of vector data. On the client side they use a plugin for OpenJUMP. They then wanted to make the Web Gen WPS accessible from additional GIS platforms and chose ArcGIS as the next target platform. Our mission was to mature our existing prototypical ArcMap WPS client and enable it to work with the WebGen WPS. The existing OpenJUMP client for WebGen WPS is limited to WebGen WPS. It is common that WPS clients can only connect to specific WPS instances, due to the openness of the WPS standard regarding input and output data types. There is practically no limit to what a complex input/output can be. Therefore, a client that needs to handle these inputs and outputs can not support all possible data types. The idea for an Extensible WPS ArcMap client was born.