The Open Grid Services Architecture (OGSA) is a specification for a grid computing environment for business and scientific use. OGSA is based on several other web service technologies, notably WSDL and SOAP. The OGSA specification is implemented in the Globus Toolkit 3 framework. You can download it for free from the The Globus Alliance.

The OGSA specification is given in the paper "The Physiology of the Grid" by Ian Foster, Carl Kesselman, Jeffrey M. Nick, and Steven Tuecke.