Web ServicesWeb Services

ASP.NET Web ServicesASP.NET Web Services Goals of ASP.NET Web services:Goals of ASP.NET Web services:

To enable cross-platform, cross-To enable cross-platform, cross-business computingbusiness computing

Great for “service” based operations Great for “service” based operations that have few methods: Google that have few methods: Google searches, Amazon integration, etc.searches, Amazon integration, etc.

ASP.NET Web services are ASP.NET Web services are “method-oriented”, not object-“method-oriented”, not object-orientedoriented Everything is passed by value: no Everything is passed by value: no

references to server objectsreferences to server objects

ASP.NET Web ServicesASP.NET Web Services Usually uses SOAP over HTTP POST – Usually uses SOAP over HTTP POST –

platform independent messagesplatform independent messages Hosted in IISHosted in IIS

Can use built-in authentication and Can use built-in authentication and encryption via IISencryption via IIS

Technically stateless, but can use regular Technically stateless, but can use regular ASP.NET Session variablesASP.NET Session variables

Very easy to use, with good support in Visual Very easy to use, with good support in Visual Studio.NETStudio.NET

Doesn’t support:Doesn’t support: Events / callbacksEvents / callbacks Object referencesObject references

Standards-BasedStandards-Based

SOAP (Simple Object Access Protocol)SOAP (Simple Object Access Protocol) XML-based protocol for messagingXML-based protocol for messaging

WSDL (Web Service Description Language)WSDL (Web Service Description Language) Document describing the message Document describing the message

exchange contractexchange contract

DISCO (Discovery)DISCO (Discovery) Simple protocol for publishing available services Simple protocol for publishing available services

UDDI (Universal Description Discovery and UDDI (Universal Description Discovery and Integration)Integration) Yellow pages directory for servicesYellow pages directory for services

SOAPSOAP Simple Object Access ProtocolSimple Object Access Protocol

XML based protocol to exchange XML based protocol to exchange structured and typed informationstructured and typed information

Remote Procedure Calls (RPC)Remote Procedure Calls (RPC) Serialization Rules (XSD)Serialization Rules (XSD) ExtensibleExtensible

WSDLWSDLWeb Service Definition LanguageWeb Service Definition Language

An XML-based grammar for describing An XML-based grammar for describing the capabilities of Web Servicesthe capabilities of Web Services

ExtensibleExtensible Jointly developed by Microsoft and IBMJointly developed by Microsoft and IBM Similar in concept to IDL, but it’s not IDLSimilar in concept to IDL, but it’s not IDL

To parse WSDL you need XML parserTo parse WSDL you need XML parser

UDDIUDDIUniversal Description, Discovery and IntegrationUniversal Description, Discovery and Integration

A project to speed interoperability A project to speed interoperability and adoption for web servicesand adoption for web services Standards-based specifications for Standards-based specifications for

service description and discoveryservice description and discovery Shared operation of a business registry Shared operation of a business registry

on the webon the web Partnership among industry and Partnership among industry and

business leadersbusiness leaders Open process with clear roadmap to Open process with clear roadmap to

a standards bodya standards body

Publ

ish Find

Bind

Internet

Overview of XML Web Service Overview of XML Web Service ArchitecturesArchitectures

XML Web Service Provider

XML Web Service Consumer

UDDI(XML Web Service Broker)

Web Services As an Implementation of a Web Services As an Implementation of a Service-Oriented ArchitectureService-Oriented Architecture

UDDI

AnyClient

SOAP

SOAP

.NET Web Service

SOAP

IIS

DiscoveryDiscovery

Let me talk to you (SOAP)Let me talk to you (SOAP)

Web Services (In Practice)Web Services (In Practice)

Design-Time or DynamicDesign-Time or Dynamic RuntimeRuntime

http://yourservice.comhttp://yourservice.com

HTML or XML with link to WSDLHTML or XML with link to WSDL

How do we talk? (WSDL)How do we talk? (WSDL)http://yourservice.com/?WSDLhttp://yourservice.com/?WSDL

XML with service descriptionsXML with service descriptions

http://yourservice.com/svc1http://yourservice.com/svc1

XML/SOAP BODYXML/SOAP BODY

Web Web ServiceService

WebWebService Service

ConsumerConsumer

UDDIUDDI

Find a ServiceFind a Servicehttp://www.uddi.orghttp://www.uddi.org

Link to DISCO or WSDL documentLink to DISCO or WSDL document

XML Web Services MappingXML Web Services Mapping

DataData

SchemaSchema

ServicesServices

InvocationInvocation

WebWeb

XMLXML

XSDXSD

WSDLWSDL

SOAPSOAP

ApplicationApplicationConceptsConcepts FrameworkFramework

ObjectsObjects

ClassesClasses

MethodsMethods

CallsCalls

The .NET Framework providesThe .NET Framework providesa bi-directional mappinga bi-directional mapping

Simple ExampleSimple Example

<%@ WebService Language="C#" Class="HelloWorld" %>

using System;

using System.Web.Services;

public class HelloWorld : WebService {

  [WebMethod]

public String SayHelloWorld() {

return "Hello World";

}

}

SOAPSOAP

Simple Object Access ProtocolSimple Object Access Protocol

XML-based standard that defines how XML-based standard that defines how method calls can be made over HTTP, method calls can be made over HTTP, and how the server’s response should and how the server’s response should be formattedbe formatted

You need to know it becauseYou need to know it because in certain circumstances where you might in certain circumstances where you might

want to use SOAP to exchange special want to use SOAP to exchange special “meta” information along with each “meta” information along with each method callmethod call

SOAP ElementsSOAP Elements

Envelope (mandatory)Envelope (mandatory) Top element of the XML document representing the Top element of the XML document representing the

messagemessage Header (optional)Header (optional)

Determines how a recipient of a SOAP message Determines how a recipient of a SOAP message should process the messageshould process the message

Adds features to the SOAP message such as Adds features to the SOAP message such as authentication, transaction management, message authentication, transaction management, message routes, etc…routes, etc…

Body (mandatory)Body (mandatory) Exchanges information intended for the recipient of Exchanges information intended for the recipient of

the message. the message. Typical use is for RPC calls and error reporting.Typical use is for RPC calls and error reporting.

<?xml version="1.0" encoding="utf-8"?> <?xml version="1.0" encoding="utf-8"?> <soap:Envelope …> <soap:Envelope …>

<soap:Header> <soap:Header> <AuthHeader xmlns="http://tempuri.org/"> <AuthHeader xmlns="http://tempuri.org/">

<Username>avi</Username> <Username>avi</Username> <Password>xM76w@</Password> <Password>xM76w@</Password>

</AuthHeader> </AuthHeader> </soap:Header> </soap:Header> <soap:Body> <soap:Body>

<Add xmlns="http://tempuri.org/"> <Add xmlns="http://tempuri.org/"> <a>23</a> <a>23</a> <b>44</b> <b>44</b>

</Add> </Add> </soap:Body> </soap:Body>

</soap:Envelope> </soap:Envelope>

POST /HelloWorld/Hello.asmx HTTP/1.1 Host: localhost Content-Type: text/xml; charset=utf-8 Content-Length: length SOAPAction: "http://tempuri.org/Add"

SOAP FaultSOAP Fault

Used to carry error and/or status information Used to carry error and/or status information within a SOAP messagewithin a SOAP message

Appears within the SOAP bodyAppears within the SOAP body Defines the following:Defines the following:

faultcode (mandatory)faultcode (mandatory) Faultstring (mandatory)Faultstring (mandatory) faultactor (optional)faultactor (optional) DetailDetail

SOAP Fault ExampleSOAP Fault Example

<SOAP:Fault> <faultcode>SOAP:Server</faultcode> <faultstring>Internal Application Error</faultstring> <detail xmlns:f=“http://www.a.com/CalculatorFault”> <f:errorCode>794634</f:errorCode> <f:errorMsg>Divide by zero</f:errorMsg> </detail></SOAP:Fault>

Soap ExtensionsSoap ExtensionsCreatingCreating

Create a class derived from Create a class derived from SoapExtensionSoapExtension

Create a class derived from Create a class derived from SoapExtensionAttributeSoapExtensionAttributeOverload the constructor if necessaryOverload the constructor if necessaryDefine any custom propertiesDefine any custom propertiesOverload the ‘ExtensionType’ property to Overload the ‘ExtensionType’ property to

return the type of your derived return the type of your derived SoapExtension classSoapExtension class

Apply the attribute to a web method or Apply the attribute to a web method or web service classweb service class

Soap ExtensionsSoap ExtensionsUsesUses

Used for More Advanced FunctionalityUsed for More Advanced Functionality Intercept Calls to a Web ServiceIntercept Calls to a Web Service Intercept Calls to a Web MethodIntercept Calls to a Web Method Pre and Post ProcessingPre and Post Processing

TracingTracingEncryptionEncryptionCompressionCompression