Web Services (which are essentially standardized communication over SOAP) contain both a document-style and an rpc-style way of using web services. The RPC-style invocations are very similar to other RPC technologies. It's just based on (standard) XML, which is a lot easier from platform independence point of view. In other words, Web Services are in a way RPC. Plus some extra. So, RPC is (still) not going anywhere - in fact you could say the opposite. It's becoming more and more common. [ May 06, 2003: Message edited by: Lasse Koskela ]
Web services are : - Business functionalities exposed as services over internet. - A programmable application logic providing data and services to other applications over internet. - Based on Internet protocols and standards. - Based on XML standards and provides cross-platform and cross-language solution. There are two types Web-services communication styles: RPC-oriented Web services: Synchronous, point to point, not persistent Sends data formatted to a procedural call Document-oriented Web services: Data formatted as an XML document Asynchronous service interactions (like Messaging) SOAP facilitates communication in Web services. It establishes Wire protocol for communication �similar to� IIOP for CORBA and JRMP for RMI. But in case of SOAP, XML is used for data encoding as �text� based protocol. SOAP Supports XML-based RPC Web services and XML Messaging (Document oriented Web services. To add more clarity on SOAP, SOAP is NOT a component model like EJB, JavaBeans etc. SOAP is NOT a programming language like Java or C++. SOAP is NOT an alternative to distributed computing and does not replace RMI or CORBA. SOAP is NOT a solution for all ! In Java Web services, JAX-RPC facilitates RPC base Web services and JAXM/SAAJ facilitates Document oriented Web services. Send me an email: firstname.lastname@example.org, if you need a copy of my Web services presentation.
SOAP over HTTP differs from SOAP over SMTP (mail) on the transport level (which is kinda obvious from the names:) In other words, the two differ from each other in the way the SOAP Envelope is encoded into the wire protocol message for transportation.