Introduction to Web Services Instructor: Dr. M. Anwar Hossain

Agenda o What is a Web service? o Technologies used o XML, SOAP, WSDL and UDDI o Walkthrough creating a Web service o Walkthrough creating a Web service client o References o Q&A

What is a Web Service o A programmable application component that is accessible via standard Internet protocols o Web page with functions o Communicate using open protocols o Self-contained and self-describing o Can be discovered using UDDI o Web services can be used by other applications o XML is the basis for Web services o Examples: stock quotes, traffic conditions, calculators, news, weather, et cetera By Web Service application can publish its function or message to the rest of the world.

Technologies used o Standard way to represent data o XML (and XML schemas) o Common, extensible message format o SOAP o Common, extensible contract language o Web Services Description Language (WSDL) o Way to discover service providers o Universal Description, Discovery, and Integration (UDDI)

XML o Extensible Markup Language o Describing documents with structured data o Industry standard o XML Schemas – XSD o XML based o Language for describing data types

SOAP o A simple, XML-based protocol for exchanging structured and type information on the Web o Industry standard o Lightweight and XML-based protocol o SOAP is a communication protocol o SOAP is a format for sending messages o Can support different protocols and formats: HTTP, SMTP, and MIME o SOAP message

WSDL o WSDL stands for Web Services Description Language o Used to describe Web services o Used to locate Web services o WSDL is a W3C standard o WSDL describes o Define data types (XSD) o Define messages in terms of types o Define bindings to transport protocol, message format o SOAP 1.1, HTTP Get/Post, MIME

UDDI o Universal Description, Discovery, and Integration o Enables businesses to publish and discover information about who provides what services o UDDI is a directory for storing information about web services o Builds on HTTP, XML, and SOAP o UDDI is built into the Microsoft.NET platform

Example Web Service Imports System Imports System.Web.Services Public Class TempConvert :Inherits WebService ** VBScript code

Example Web Service Public Function FahrenheitToCelsius (ByVal Fahrenheit As String) As String dim fahr fahr=trim(replace(Fahrenheit,",",".")) if fahr="" or IsNumeric(fahr)=false then return "Error" return ((((fahr) - 32) / 9) * 5) end function ** VBScript code

Example Web Service Public Function CelsiusToFahrenheit (ByVal Celsius As String) As String dim cel cel=trim(replace(Celsius,",",".")) if cel="" or IsNumeric(cel)=false then return "Error" return ((((cel) * 9) / 5) + 32) end function end class ** VBScript code

Example Web Service