CSC8530 Distributed Systems XML Web Services David Vaglia

XML Web Service Expose useful functionality to Web users through a standard Web protocol. Describe their interfaces in enough detail to allow user to build a client application. Usually provided in a Web Services Description Language (WSDL) document. Registered so that users can find them. Universal Discovery Description and Integration (UDDI) Standard Data Format

SOAP Simple Object Access Protocol Specification that defines XML format for messages Optional – Represent Program Data, do RPC HTTP message Many Implementations Implemented on many hardware and software platforms Security?

WSDL XML Web Services Description Language Describes a set of SOAP messages and how they are exchanged Describes location of Service and Communication protocol Specification is at

UDDI Universal Discovery Description and Integration UDDI directory entry is a XML files that describes a business and services it offers White pages, Yellow Pages, Green Pages Type Model or tModel contains WSDL file that describes a SOAP interface to a XML Web Service Searchable

Calculator App

XML Request

XML Response

SOAP Message Format <soap:Envelope xmlns:soap="...">

SOAP Request POST /mortgagecalc/mc.asmx HTTP/1.1 Host: example.org Content-Type: text/xml; charset=utf-8 Content-Length: 323 SOAPAction: " <soap:Envelope xmlns:soap=" billy yllib <m:CalculateMortgage xmlns:m="

Web Services Platform

Dist Application Missing Features Security Routing Transactions Reliable Messaging Add-Ons Available

OPC XML DA DCOM Replacement

OPC XML DA Subscription

OPC XML Performance Evaluation Much slower on Internet than Intranet Data must pass through Firewall and Web Server Security again is a concern Progression to web services is not straight forward OPC Technology is now available on Internet