Writing RPC Services

Writing an RPC-based SOAP service is a very trivial undertaking, and really only involves the following two basic steps:

1. Create a code artifact which is supported by one of the Apache SOAP providers; either a standard Java class (including Java Beans,) an EJB, or a BSF supported script. The code artifact does not have to know anything about Apache SOAP, as you will simply be exposing either a method or a script function that exists within the artifact. For example, if you create a Java class that has a method called add(), then you could expose that method as a SOAP service. Multiple methods may be exposed for a single service, as is described in the next section.
   Note that parameters to your method/function must be serializable by SOAP, and so must exist within the SOAP mapping registry. For information on creating type mappings, look here.
   
   
2. Create an Apache SOAP deployment descriptor for your service. The deployment descriptor provides the implementation with the information necessary to handle requests for an offered service. For a Java service implementation, this will include such information as the name of the class which is providing the implementation, as well as the name of the methods which are to be exposed. More information about the deployment descriptors may be found here.
   

In a Java based service implementation, you may throw a SOAPException to indicate that some error has occurred when processing the request. Throwing a SOAPException(FAULT_CODE_CLIENT, ...) will allow your service implementation to indicate that the failure was due to a client error, whereas throwing a SOAPException(FAULT_CODE_SERVER, ...) will indicate that your service implementation was at fault. (If you throw any other type of exception, the server will catch it, and will pass it on as a SOAPException(FAULT_CODE_SERVER, ...)) See the SOAP v1.1 specification for more information on SOAP Faults.

Last updated 5/18/2001 by Bill Nagy <nagy@watson.ibm.com>.