Figure 1.

The most basic SADI service transaction. In (A) the client calls HTTP GET on the service endpoint. This results in the retrieval of a service interface document (B) containing references to OWL classes (defined anywhere on the Web) that describe the input and output datatypes of that service. The client finds RDF data matching the service's input OWL class (based on the property restrictions of that class) and passes that data to the service endpoint using simple HTTP POST (C). The service strips the properties from the input RDF node, uses that information to execute its analysis, and adds the results as new properties of the input node before returning it to the client as appropriately typed output (D).