Web Services Dr. Herbert Praehofer Institute for System Software Johannes Kepler University Linz Dr....

Web Services

Dr. Herbert PraehoferInstitute for System Software Johannes Kepler University Linz

Dr. Dietrich BirngruberSoftware Architect TechTalkwww.techtalk.at

© University of Linz, Institute for System Software, 2004published under the Microsoft Curriculum License

Web Services Introduction

Web Services in .NET

SOAP

SOAP and .NET

Service Description with WSDL

Discovery of Web Services: UDDI and DISCO

Preview of Web Services .NET 2.0

Summary

3

Motivation

• Integration of heterogonous, distributed systems– globally distributed

– different programming languages

– different APIs

• B2C and B2B applications

• Usage of globally distributed services

Example: Travel Agent Service

taken from: Web Services Architecture Usage Scenarios,W3C Working Group Note, 11 February 2004,http://www.w3.org/TR/2004/NOTE-ws-arch-scenarios-20040211/

4

What are Web Services?

• Middleware for distributed applications

• For remote procedure calls und data exchange

• Open standard based on XML

• For loosely coupled software services

• Independent of programming languages and operating systems

• Utilizing existing Internet protocols and server architectures

5

Definition Web Service (by W3C)

• Software application identified by URI

• interface description in XML

• with interaction on the basis of XML encoded messages

• and message exchange on the basis of Internet protocols

6

Independence and Integration through ...

• SOAP – XML standard for message encoding– independent of transport protocol– independent of client and server implementations: Java, .NET, Python, …

• Web Services Description Language - WSDL (1.1)– Interface description in XML

• communication on the basis of existing protocols and server architectures– HTTP and Web server– SMTP and mail server – FTP and FTP server

• Standardisation (W3C)– SOAP 1.2, WSDL 1.1 (1.2 und 2.0)– additional protocols based on SOAP and WSDL– protocol bindings (HTTP)

7

Web Services Scenario

IIS (.NET web service container)

WebService A

WebService B

web server + Javaweb service

container

Web-Service C

SOAPHTTP

e-mail server +SOAP processor

WebService

D.NET client

Java client

script client

SOAPSMTP

SOAPprotocol

remoteprocedure call

... client

SOAPHTTP

SOAPHTTP

SOAPHTTP

SOAPprotocol X

SOAPSMTP

8

Web Services in Comparison

Java RMI .NET Remoting CORBA Web services

Programming language

Java .NET languages (C#, VB.NET, ..)

independent independent

Interface definition

Java Interfaces C# Interfaces CORBA IDL WSDL (XML-based)

Data structures Java objects .NET objects IDL-specified objects

XML data

Transport protocol

RMI-IIOP binary or OAP GIOP/IIOP HTTP, HTTPS, SMTP, FTP

Packaging Java object serialisation

.NET object serialisation

ORB/CDR SOAP

Infrastructure Java RMI infrastructure

.NET remoting infrastructure

ORBs Web, Mail, FTP server

9

Pros and Cons

• Pros – independent of programming language, run time environment and

operating system

– Built on existing Internet infrastructure

– standardized

– promoted from important players (Microsoft, IBM, SAP, Sun)

• Cons – performance (XML)

10

Web Service Infrastructure

client(s)

E.g.: UDDI,DISCO

Discover ServicesWhat services do exist?Where are they? (URL)

Servide Description (in WSDL)What message does the serviceknow and how are those called?

Service CallsUsing services via

SOAP, HTTP, XML-RPC, ... Web Service+ container

11

Web Service Architecture

Client

Web servicecontainer

WebService

Discovery service

WSD1 URL1

WSD2 URL2

... ...

call

inquiry

12

Web Service Architecture (2)

ClientWeb service

container

Discovery service

WSD1 URI1

WSD2 URI2

... ...

Webservice

service inquiry (URI)

service description (WSD)

service inquiry

service description (WSD)

service call

result

service call (SOAP)

result: SOAP



SOAP

SOAP and .NET




Summary

14


• IIS and ASP.NET infrastructure support web services

• .NET Framework provides several– base classes

– attributes

– protocols

for the realization of web services

• Visual Studio.NET provides powerful tools for developing web services – implementation

– testing

– administration of IIS

– generation of proxy code (wsdl.exe)

15

.NET Namespaces

• System.Web.Services – for developing web services (e.g.: WebService, WebMethod)

• System.Web.Services.Configuration – for extending SOAP

• System.Web.Services.Description – for creating and manipulating WSDL descriptions

• System.Web.Services.Discovery – for using DISCO

• System.Web.Services.Protocols – for implementation of communication protocols (e.g. SOAP-

HTTP)

• System.Xml.Serialization– for XML serialization

16

Implementation of Web Services

public class MyWebService : WebService {

• deriving from base class System.Web.Services.WebService

[WebMethod(Description= “comment ")][…]public Returntype MyWebMethod( …) {

…

• Identification and settings by .NET attributes– identification of web service methods

– definition of format and encoding

– XML namespaces and element names to use

– etc.

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

• in asmx-file with @WebService directive

17

Example: TimeService

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

using System;using System.Web.Services;

public class TimeService : WebService {

[WebMethod(Description="Returns the current time")]public string GetTime(bool shortForm) {

if (shortform) return DateTime.Now.ToShortTimeString(); else return DateTime.Now.ToLongTimeString();

}}

TimeService.asmx

WebService directive

deriving from WebService

Attribute [WebMethod] identifies web service method

18

Example: Simple .NET Client

using System;using TimeClient; //Namespace des erzeugten Proxies

public class NetClient {public static void Main(string[] args) {

TimeService service = new TimeService();Console.WriteLine("Die Zeit am Server ist: ");string time = service.GetTime(true);Console.WriteLine(time);

}}

• Client program creates TimeService object and calls GetTime

> wsdl.exe /namespace:TimeClient /out:TimeServiceProxy.cs http://localhost/netsem-ws/MyFirstService.asmx

• wsdl.exe generated proxy for client (TimeClient.TimeService)

19

Example: Simple Java Client

• Using GLUE tool + Java libraries:– wsdl2Java create Java interface (ITimeServiceSoap) and proxy

(TimeServiceHelper)

import Kapitel7.GLUEProxy.*; // import generated GLUE proxy classes /** Simple XML web service client in Java using GLUE */public class JavaClientGLUE {

public static void main(String[] args) {try {

// Calling service using class and interface generated by wsdl2javaITimeServiceSoap service = TimeServiceHelper.bind();String time = service.GetTime(true);System.out.println(“The time on the server is: \n" + time);

} catch (Exception ex) { ex.printStackTrace(); }}

}



SOAP

SOAP and .NET




Summary

21

SOAP

• Simple message protocol in XML– for packaging arbitrary application data

– single messages only („one-way“)

– asynchronous

• Independent of transport protocol

• SOAP does not define: – distributed object model

– communication protocol

– distributed garbage collection

– distributed events (distributed callbacks)

22

Application of SOAP

• SOAP is extendable – method call protocol (RPC)– security – authentication – etc.

• Protocol realisation by combination of messages (message exchange patterns)– one-way, request-response, multicast, …

1: GetTime_Request

2: GetTime_ResponseClient Server

e.g.: request-response for RPC by 2 messages

23

SOAP Messages

<Envelope>

<Header>

<Body>

Data

Message Header

Message Header

<Fault> Fault Descriptions

• envelope (<Envelope>) as container

• letter head (<Header>) with meta information (Message Headers)

• letter (<Body>)

• with arbitrary XML data

• fault descriptions

SOAP messages comparable to letters with

24

XML Structure (simplified, SOAP 1.2)

<?xml version="1.0" ?> <soap:Envelope xmlns:soap="...">

<soap:Header>  <m:my xmlns:m="anURI" soap:mustUnderstand=“true" soap:role=“uri2" /> ...

</soap:Header>

<soap:Body> data (depends on encoding and format)<soap:Fault>

<soap:Code>...who is responsible?... </Code> <soap:Reason>...textual description...</soap:Reason> <soap:Detail>...more error details...</soap:Detail>

</soap:Fault> </soap:Body>

</soap:Envelope>

25

Data in <Body> Part

• Message format: – document structure defined by XML schema

– rpc structure defined by SOAP for RPC

• Data encoding:– literal encoding defined by XML schema

– encoded encoding defined by SOAP encoding rules

• Usual combinations: – document/literal standard in .NET

– rpc/encoded often used by Java servers

26

HTTP Binding

• HTTP-GET, HTTP-POST– call encoded in HTTP (URL encoded)

– response encoded in XML

Restricted to simple calls (no headers, no structured data)

• SOAP over HTTP-POST– data part of POST request contains SOAP encoded call

– response SOAP encoded

No restrictions

27

Example: HTTP-POST

Call of GetTime(bool shortForm) of web service http://localhost/time/TimeService.asmx

http://localhost/time/TimeService.asmx/GetTime?shortForm=true

• Call :

HTTP/1.1 200 OK Content-Type: text/xml; charset=utf-8 Content-Length: length <?xml version="1.0" encoding="utf-8"?> <string xmlns="http://tempuri.org/">string</string>

• HTTP response:

28

Example: SOAP over HTTP (1)

POST /time/TimeService.asmx HTTP/1.1Content-type: text/xml; charset=utf-8SOAPAction: http://dotnet.jku.at/GetTimeContent-length: 198User-Agent: Java1.4.0Host: localhostAccept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2Connection: keep-alive

<?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">

<soap:Body><GetTime xmlns="http://tempuri.org/"

<shortForm>true

</shortForm>< /GetTime>

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

• SOAP over HTTP-POST:

Web method

Parameter

HTTP-header SOAPAction identifies SOAP-request

29

Example: SOAP over HTTP (2)

• SOAP encoded response:

HTTP/1.1 200 OK Content-Type: text/xml; charset=utf-8 Content-Length: length <?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap=http://schemas.xmlsoap.org/soap/envelope/

xmlns:xsi=http://www.w3.org/2001/XMLSchema-instancexmlns:xsd="http://www.w3.org/2001/XMLSchema"><soap:Body>

<GetTimeResponse xmlns="http://tempuri.org/"><GetTimeResult>string</GetTimeResult>

</GetTimeResponse></soap:Body>

</soap:Envelope>

Return value



SOAP

SOAP and .NET




Summary

31

SOAP and .NET

.NET provides support for

– defining message format and encoding

– encoding of .NET data types

– development of message headers

– life cycle management

32

Message Format and Encoding (1)

• Attributes SoapRpcService and SoapRpcMethod for rpc format

• with parameters - Use: encoding (SoapBindingUse.Literal or SoapBindingUse.Encoded)

- Action: URI for SOAPAction-HTTP header

- RequestNamespace and RequestElementName: namespace and name of SOAP element for request

- ResponseNamespace and ResponseElementName: namespace and name of SOAP element for response

[SoapRpcMethod(Use=SoapBindingUse.Encoded

Action="http://dotnet.jku.at/Sample/AddAddressRpc“, // SOAP action RequestNamespace="http://dotnet.jku.at/Sample/Request",

RequestElementName="AddAddressRpcRequest", // SOAP element name ResponseNamespace="http://dotnet.jku.at/Sample/Response",ResponseElementName="AddAddressRpcResponse")] // SOAP element name

[WebMethod(Description="Adds an address DataSet for the specified user")]public void AddAddressRpc(long userID, Address address) { ... }

33

Message Format and Encoding (2)

• Attributes SoapDocumentService and SoapDocumentMethod for document format

[SoapDocumentMethod(Use=SoapBindingUse.Literal,Action="http://dotnet.jku.at/Sample/AddAddressDocLit", // SOAPActionRequestNamespace="http://dotnet.jku.at/Sample/Request", RequestElementName="AddAddressDocLitRequest", // SOAP element name ResponseNamespace="http://dotnet.jku.at/Sample/Response",ResponseElementName="AddAddressDocLitResponse")] // SOAP element name

[WebMethod(Description="Adds an address DataSet for the specified user")]public void AddAddressDocLit(long userID, Address address) { ... }

[SoapDocumentService(Use=SoapBindingUse.Encoded)]

public class TimeService : WebService { ... }

34

SOAP Encoding of .NET Data Types

• Serializing of .NET data types

– on the basis of SOAP encoding rules http://schemas.xmlsoap.org/soap/encoding

– adjusted by attributes (namespace System.Web.Serialization)

SoapAttributeAttribute Serializing field as XML attribute

SoapElementAttribute Serializing field as XML element

SoapIgnoreAttribute No serialization of field

SoapIncludeAttribute Including a type

SoapEnumAttribute Adapting name of enumeration

35

Example: Encoding of a Type (1)

• Web method GetTimeDesc uses type TimeDesc for return value

[WebMethod(Description="Returns the time description of the server")]public TimeDesc GetTimeDesc() {

TimeDesc td = new TimeDesc();// ...return td;

}

public struct TimeDesc {[SoapAttribute] public string TimeLong;[SoapAttribute] public string TimeShort;[SoapAttribute (AttributeName = "ZoneID")] public int TimeZone;

}

• Encoding of TimeDesc adjusted by attribute [SoapAttribute] fields encoded as XML attributes

36

Example: Encoding of a Type (2)

...<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" ...

<soap:Body soap:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><types:GetTimeDescResponse>

<GetTimeDescResult href="#id1" /></types:GetTimeDescResponse><types:TimeDesc id="id1" xsi:type="types:TimeDesc"

types:TimeLong="10:00:25" types:TimeShort="10:00" types:ZoneID="1" /></soap:Body>

</soap:Envelope>

• SOAP encoded response

37

Including Types

• SoapIncludeAttribute allows inclusion of types

important for specializations

Customer and Employee have to be included explicitly into web service description!

Example: PersonService

public class PersonService : WebService {

[WebMethod]…public Person[ ] GetAll() {…}

}

Web method with return value of type Person[]

Person

Customer Employee

Person has 2 specializations Customer and Employee

38

Example: PersonService (1)

• Classes Person, Customer and Employee

public abstract class Person { …}public class Customer : Person { …}public class Employee : Person {…}

<%@ WebService Language="C#" Class="PersonService" %>using System; … using System.Xml.Serialization;public class PersonService : WebService {

[WebMethod] [SoapRpcMethod][SoapInclude(typeof(Customer)), SoapInclude(typeof(Employee))]public Person[] GetAll() {

Person[] data = new Person[2];data[0] = new Customer("1“, "Max Customer", "EMP-33");data[1] = new Employee("EMP-33", "Tom Employee");return data;

}}

• PersonService defines web method GetAll with return type Person[]• SoapInclude attribute includes Customer and Employee types

39

Example: PersonService (2)

• SOAP encoded response<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" ... >

<soap:Body soap:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><tns:GetAllResponse>

<GetAllResult href="#id1" /></tns:GetAllResponse><soapenc:Array id="id1" soapenc:arrayType="types:Person[2]">

<Item href="#id2" /><Item href="#id3" />

</soapenc:Array><types:Customer id="id2" xsi:type="types:Customer">

<SSN xsi:type="xsd:string">1</SSN><Name xsi:type="xsd:string">Max Customer</Name><EmpSSN xsi:type="xsd:string">EMP-33</EmpSSN>

</types:Customer><types:Employee id="id3" xsi:type="types:Employee">

<SSN xsi:type="xsd:string">EMP-33</SSN><Name xsi:type="xsd:string">Tom Employee</Name>

</types:Employee></soap:Body>

</soap:Envelope>

40

SOAP Header Entries

• SOAP header entries are used for metainfos in messages

• Arbitrary header entries are possible

• All header entries have attributes – recipient of entry (Actor)

– if it must be handled by recipient (mustUnderstand)

• .NET supports header entries by:– Class SoapHeader: development of header entry classes

– Attribute SoapHeaderAttribute: Defining header entries for web methods

41

Classes SoapHeader and SoapHeaderAttribute

SoapHeader

//----- propertiespublic string Actor { get; set; }public bool MustUnderstand { get; set; }public bool DidUnderstand { get; set; }...

• Recipient

• Header must be handled

• Header handled successfully

public string Actor {get; set;}

public bool DidUnderstand {get; set;}

public bool MustUnderstand {get; set;}

SoapHeaderAttribute

//----- propertiespublic SoapHeaderDirection Direction {get; set;}public string MemberName {get; set;}...

• In-, Out-, InOut direction of headers

• Name of field of web service class for header entry

public SoapHeaderDirection Direction {get; set;}

public string MemberName {get; set;}

42

Example: AuthHeader (1) User indentification in TimeService

– Login returns identification code (cookie)

– GetTime sends back identification code in header entry

• Header class AuthHeader defines public field cookie

public class AuthHeader : SoapHeader { public string cookie; }

• Web service class defines field curUser to store AuthHeader object

[WebService(Namespace="http://dotnet.jku.at/time/")]public class HeaderTimeService : WebService {

public AuthHeader curUser;

• Login with user and password returns identification string

[WebMethod (Description="Authenticates the user")]public string Login(string user, string pwd) { ... create cookie ... }

bool ValidateCookie(string cookie) { ... validate cookie ... }

43

Example: AuthHeader (2)

• GetTime requires header entry of type AuthHeader which will be stored in field curUser

• Validates user based on login data

[WebMethod(Description="Returns the current time")][SoapHeader("curUser")]public string GetTime() {

if (curUser != null && ValidateCookie(curUser.cookie))return System.DateTime.Now.ToLongTimeString();else throw new SoapHeaderException("Access denied!",

SoapException.ClientFaultCode);}

44

Example: AuthHeader (3)

• Client – creates service proxy and AutHeader object

HeaderTimeService proxy = new HeaderTimeService();AuthHeader entry = new AuthHeader();

– receives cookie from call to Login

entry.cookie = proxy.Login(user, pwd);

– sets the AuthorHeader in proxy – calls GetTime with AuthHeader header entry

entry.cookie = proxy.Login(user, pwd);proxy.AuthHeaderValue = entry;Console.WriteLine(proxy.GetTime());

<?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap="http://..." ... >

<soap:Header><AuthHeader xmlns="http://dotnet.jku.at/time/">

<cookie>aewt12348cvNNgrt55</cookie></AuthHeader>

</soap:Header><soap:Body>

<GetTime xmlns="http://dotnet.jku.at/time/" /></soap:Body>

</soap:Envelope>

45

Life Cycle

• Web service objects are stateless

• Are created for each call

• Data can be stored in properties of– Application state object or

– Sesssion state object

public HttpApplicationState Application {get;}

public HttpApplicationState Session {get;}

public sealed class HttpSessionState : ICollection, IEnumerable {public object this[ string name ] {get; set;} public object this[ int index ] {get; set;} …

}

46

Example: StateDemo (1)

<%@ WebService Language="C#" Class="StateDemo" %>using System.Web.Services;[WebService(Namespace="http://dotnet.jku.at/StateDemo/")]public class StateDemo : WebService {

Web service StateDemo demonstrates storage of data

• IncApplication increases property "Hit" of Application state object

[WebMethod()]public int IncApplication() {

int hit = (Application["Hit"] == null) ? 0 : (int) Application["Hit"];hit++;Application["Hit"] = hit;return hit;

}

47

Example: StateDemo (2)

• Parameter EnableSession enables usage of Session object

• IncSeesion increases property "Hit" of Session state object

[WebMethod(EnableSession=true)]public int IncSession() {

int hit = (Session["Hit"] == null) ? 0 : (int) Session["Hit"];hit++;Session["Hit"] = hit;return hit;

}}



SOAP

SOAP and .NET




Summary

49

Web Service Description Language (WSDL)

• WSDL is an XML based IDL for web services

• a WSD describes: – used data types

– structure of messages

– operations (methods)

– protocols to call operations

– addresses of web service

current version in .NET: WSDL 1.1 (http://schemas.xmlsoap.org/wsdl/)

Working Draft: WSDL 2.0 (10/4/2004)

50

concrete part

abstract part

Structure of WSDL 1.1

<definitions><types></types><message>

<part> </part>

</message><portType>

<operation> <input><output>

</operation></portType><binding>

<operation></binding><service>

<port></service>

</definitions>

WSDL description of a web services types defined in <xsd:schema>

simple messages parts of messages

interface specification operations of an interface

input message output message

binding of interface to protocols and encoding description of the binding for each operation

service descriptionURI and binding to port

51

Example: WSDL for TimeService (1)

• WSDL description created by web container (IIS)http://localhost/WebProject1/TimeService.asmx?WSDL

<?xml version="1.0" encoding="utf-8"?><definitions xmlns:soap=http://schemas.xmlsoap.org/wsdl/soap/

xmlns:tns="http://dotnet.jku.at/time/" xmlns:s="http://www.w3.org/2001/XMLSchema“xmlns:http="http://schemas.xmlsoap.org/wsdl/http/“xmlns:mime="http://schemas.xmlsoap.org/wsdl/mime/“xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/“targetNamespace="http://dotnet.jku.at/time/" xmlns="http://schemas.xmlsoap.org/wsdl/">

<types /><message name="GetTimeSoapIn" /><message name="GetTimeSoapOut">

<part name="GetTimeResult" type="s:string" /></message><portType name="TimeServiceSoap">

<operation name="GetTime"><input message="tns:GetTimeSoapIn" /><output message="tns:GetTimeSoapOut" />

</operation></portType>…

abstract part

52

Example: WSDL for TimeService (2)

…<binding name="TimeServiceSoap" type="tns:TimeServiceSoap">

<soap:binding transport="http://schemas.xmlsoap.org/soap/http" style="rpc" /><operation name="GetTime">

<soap:operation soapAction="http://dotnet.jku.at/time/GetTime" style="rpc" /><input>

<soap:body use="encoded" namespace="http://dotnet.jku.at/time/“encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />

</input><output>

<soap:body use="encoded" namespace="http://dotnet.jku.at/time/“encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />

</output></operation>

</binding><service name="TimeService">

<documentation>Simple web service for querying the time</documentation><port name="TimeServiceSoap" binding="tns:TimeServiceSoap">

<soap:address location="http://localhost/time/TimeService.asmx" /></port>

</service></definitions>

concrete part



SOAP

SOAP and .NET




Summary

54

Universal, Description, Discovery and Integration (UDDI)

• Standardized protocol for searching for and using web services

• Provides web services interface

Directory(UDDI)

1.) register2.) search

3.) connect4.) call Client

Web Service A

Web Service B

http://www.uddi.org

55

DISCO

• Microsoft’s technique for dynamic usage of web services

• DISCO file

– contains XML document with URIs pointing to web services

– can be the result to a UDDI inquiry

• .NET support in namespace System.Web.Services.Discovery

56

DISCO Descriptions

• Creation of DISCO descriptions: – by command tool disco.exe

– by IIS

http://localhost/WebProject1/TimeService.asmx?DISCO

> disco.exe /out:WebProject1 WebProject1/TimeService.asmx

<?xml version="1.0" encoding="utf-8" ?> <discovery xmlns:xsd="http://www.w3.org/2001/XMLSchema„

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance„xmlns="http://schemas.xmlsoap.org/disco/"><contractRef ref="http://localhost/WebProject1/TimeService.asmx?wsdl„

docRef="http://localhost/WebProject1/TimeService.asmx„xmlns="http://schemas.xmlsoap.org/disco/scl/" />

<soap address="http://localhost/WebProject1/TimeService.asmx„xmlns:q1="http://tempuri.org/" binding="q1:TimeServiceSoap„xmlns="http://schemas.xmlsoap.org/disco/soap/" />

</discovery>

57

Example: TimeService Discovery (1)

<%@ WebService Language="C#" Class="TimeService1" %>using System.Web.Services;[WebService(Namespace="http://dotnet.jku.at/time/", Name="TimeService")]public class TimeService1 : WebService {

[WebMethod(Description="Returns the current server time")]public string GetTime() { return System.DateTime.Now.ToLongTimeString(); }

}

• 2 variants of TimeService – TimeService1

– TimeService2

<%@ WebService Language="C#" Class="TimeService2" %>using System.Web.Services;[WebService(Namespace="http://dotnet.jku.at/time/", Name="TimeService")]public class TimeService2 : WebService {

[WebMethod]public string GetTime() { return "I don’t know the time!"; }

}

58


using System; using System.Web.Services.Discovery; using System.Collections;public class DiscoSample {

public static void Main(string[] args) {

• Disco client with discovery of DISCO file

DiscoveryClientProtocol discoClient = new DiscoveryClientProtocol();foreach (string uri in args) {

discoClient.Discover(uri);}

– loading the DISCO files

discoClient.ResolveAll();TimeService proxy = new TimeService(); foreach (object obj in discoClient.Documents.Values) {

DiscoveryDocument dDoc = obj as DiscoveryDocument;

– iterating over all DISCO descriptions

59


ContractReference contr = null;IEnumerator it = dDoc.References.GetEnumerator();while (contr == null && it.MoveNext())

contr = it.Current as ContractReference;

– iterating over all <contactRef>-elements and retrieve URLs

– given URL connect to web service and call web method

if (contr != null) {proxy.Url = contr.DocRef;Print("Connecting proxy to " + proxy.Url);proxy.Discover();Print("Result of GetTime: " + proxy.GetTime());

}}

}}

static void Print(string msg) { System.Console.WriteLine(msg); }}



SOAP

SOAP and .NET




Summary

61

Indigo

• Web services in .NET 2.0 are integrated in Indigo

• Indigo unites – .NET remoting

– Web services

– .NET Enterprise Services

in one uniform programming model

• Indigo provides – transactions

– reliable communication

– secure communication and authentication

– independence of transport protocols

– host independence

– message-based server activation

62

Indigo Architecture

service

typed channel

untyped channel

port

formatter

transport

to destination

message flow

63

Indigo Web Service Example (1)

• Implementation of web service TimeService using System; using System.MessageBus.Services;[DatagramPortType(Name="TimeService", Namespace="http://dotnet.jku.at/WS")]public class TimeService {

[ServiceMethod]public DateTime GetTime() {

DateTime now = DateTime.Now;Console.WriteLine ("Time request at {0}", now); // output to monitor serverreturn now;

}}

• Compiling and creation of assembly

csc /target:library /reference:System.MessageBus.dll TimeService.cs

• Creating the WSDL description

wsdlgen TimeService.dll

64


• Implementation of the server application

using System; using System.MessageBus.Services; using System; using System.MessageBus;class Server {

static void Main () {ServiceEnvironment se = null;try {

se = ServiceEnvironment.Load();se.Open();Console.WriteLine("Press enter to stop the service ...");Console.ReadLine();

} finally { if (se != null) se.Close(); }}

}

65

Indigo Web Service Example (3)• Configuration of the server in file Server.exe.config

<configuration><system.messagebus>

<serviceEnvironments><serviceEnvironment name="main">

<port><identityRole>

soap.tcp://localhost:12345/TimeService/ </identityRole>

</port><remove name="securityManager"/> <policyManager>

<areUntrustedPolicyAttachmentsAccepted> true</areUntrustedPolicyAttachmentsAccepted><isPolicyReturned> true </isPolicyReturned>

</policyManager><serviceManager>

<activatableServices><add type="TimeService, TimeService" />

</activatableServices></serviceManager>

</serviceEnvironment></serviceEnvironments>

</system.messagebus></configuration>

66


• Compilation of the server application

csc /reference:System.MessageBus.dll Server.cs

• Creation of the proxy for the client

wsdlgen dotnet_jku_at.WS.wsdl dotnet_jku_at.WS.xsd

• Compilation of the proxy code

csc /target:library /reference:System.MessageBus.dll dotnet_jku_at.WS.cs

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• Implementation of the client application using System; using System.MessageBus.Services;public class Client {

public static void Main () {ServiceEnvironment se = null;try {

se = ServiceEnvironment.Load();ServiceManager sm = se[typeof(ServiceManager)] as ServiceManager;if (sm == null) throw new Exception("ServiceManager is not available.");se.Open();Uri uri = new Uri("soap.tcp://localhost:12345/TimeService/");// get a channel to the web service from the default service managerITimeServiceChannel channel = (ITimeServiceChannel)

sm.CreateChannel(typeof(ITimeServiceChannel), uri);Console.WriteLine(channel.GetTime());// invoke web service method

} catch (Exception e) { Console.WriteLine(e); } finally { if (se != null) se.Close(); }

}}

• Configuration of the client (analogous to the server) and compilation

csc /reference:System.MessageBus.dll,dotnet_jku_at.WS.dll Client.cs

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• Starting the server and the client

//----- Server> Host.exePress enter to stop the service ...

Time request at 1/29/2004 3:35:51 PM>

//----- Client

> Client.exeTime request at 1/29/2004 3:35:51 PM>



SOAP

SOAP and .NET




Summary

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Summary

• Web services are a middleware technology

• on the basis of XM and Internet protocols

• independent of programming language and run time system

• for the integration of heterogeneous, distributed systems

• .NET supports web services – development of web services

– development of web service clients

– discovery and dynamic connection to web services

• In .NET 2.0 Indigo unites the different remoting technologies

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Resources (apart from dotnet.jku.at)

• UDDI & Cowww.uddi.org: Homepage of UDDI initiative

www-3.ibm.com/services/uddi: Discovery service from IBM

uddi.microsoft.com: Discovery service from Microsoft

www.xmethods.com: Catalogue with UDDI- und DISCO entries

• For developers www.w3.org: Specifications

www.webservices.org: Articles and tutorials about web services

www.gotdotnet.com: Site for .NET technology, including web services

groups.yahoo.com/group/soapbuilders: Discussion group for SOAP

• Java implementations xml.apache.org/axis/: Web service server in Java based on Apache

www.themindelectric.com: GLUE: web service server in Java

Date post:	26-Mar-2015
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