Web Services, SOAP, and Web Services, SOAP, and WSDLWSDLCSCI 4300CSCI 4300

Web Services for B2B Web Services for B2B communicationcommunication

Technology involved for remote Technology involved for remote procedure callprocedure call

• Web Service Description Language is the API

• SOAP is the message envelope

• HTTP is the transport layer

Remote Method InvocationRemote Method Invocation

• Low-level• Requires all parts

written in Java• CORBA is one

attempt to get around this issue

JAX RPC layered over RMIJAX RPC layered over RMI

Simple SOAP messageSimple SOAP message

SOAP headers and bodySOAP headers and body

Headers:• Security credentials• Transaction IDS• Routing instructions• Payment tokens• Etc. etc. Body:• Actual message

content

Application-specific header Application-specific header exampleexample

A security headerA security header

Processing SOAP messagesProcessing SOAP messages

• In particular, JAX-RPC implements remote procedure calls by exchanging SOAP messages

Modular processingModular processing

Message passing: multiple actorsMessage passing: multiple actors

Who processes the headers?Who processes the headers?

• A node which has identified itself with this processing role will process this header.

SOAP use caseSOAP use case

Sequential processingSequential processing

• Processing nodes can add and remove headers• The Inventory node can add an authentication

header and force the next node to process it

Web Services Description Web Services Description LanguageLanguage

““portType”: a service access pointportType”: a service access point

Operation typesOperation types

WSDL – SOAP bindingWSDL – SOAP binding

• The binding determines the format of the SOAP message that will transport a service

UDDI: the Yellow PagesUDDI: the Yellow Pages

AcknowledgementsAcknowledgements

• Auto parts example: http://www.info.gov.hk/digital21/eng/knowledge/webservice_appexample.html

• http://today.java.net/today/2003/11/05/ch4SOAP.pdf• http://java.sun.com/developer/technicalArticles/xml/webservices/• http://www.w3schools.com/wsdl/wsdl_documents.asp