WPS enables us to issue, find and put together to processes in a uniform fashion. It is best identified as a non-REST RPC type service even if it does conform with most of the REST properties. It defines three operations: GetCapabilities (which gives back service-level metadata), DescribeProcess (which returns an overview of a process along with inputs and outputs) and Execute (returns output of a process).
Its operations can be brought up using a definite web browser by giving in queries and requests in the form of URLs via HTTP GET, or XML files through HTTP POST, of which contents are dependent on requested operations.