The Java API for XML-based RPC (JAX-RPC) provides a programming interface for utilizing remote procedure calls for interacting with webservices via the SOAP protocol. This is a purely synchronous method. The client will block while waiting for a reply from the webservice. This also provides a more rigorous definition of the data types being used for the transaction/message. The SOAP with Attachments API for Java (SAAJ) is utilized for creating and returning the graphic file as an attachment.

Webservices designed utilizing this API also make use of Web Services Description Language (WSDL) files for describing the public interface to the webservice, so that clients can utilize this interface to determine the methods exposed for public consumption. This approach tends to be more verbose and also depends upon a variety of artifacts generated by either using the JWSDP ant tasks or the binaries.

Sval-JAXRPC-Service is implemented using the JAX-RPC and SAAJ APIs and the runtime implementations provided by the JWSDP.