copyright ©2004 virtusa corporation | confidential introduction to windows communication foundation...

Copyright ©2004 Virtusa Corporation | CONFIDENTIAL

Introduction toWindows Communication Foundation

Ruwan Wijesinghe

2Copyright ©2004 Virtusa Corporation | CONFIDENTIAL

Windows Communication Foundation

• Provide a unified communication model for all windows based distributed application development technologies (ASMX web services, .Net Remoting, Enterprise Services, MSMQ)

• Fully Support WS-I and hence interoperable with applications developed in other platforms

• Support transport mediums like • TCP – Efficient intranet communication• HTTP – For communication over the fire walls (Internet) • Named Pipes – For efficient inter process communication• MSMQ – Reliable messaging

• Support three messaging patterns• Simplex – Send a message and do not expect a reply• Duplex – Send a message with a callback interface. Service can replies

asynchronously using this callback interface, if required.• Request Reply – Send a message and expect a reply


Hosting Services

• Internet Information Server (IIS) – • Supports, clustering, domain recycling, etc.

• IIS 6 supports only HTTP

• IIS7 (WAS) supports any communication protocol

• Windows Executables – Windows and Console applications can host services as s means of inter-process communication

• Windows Services – Windows services can be used to host WCF services. This can be used as a means of inter-process communication as well as for distributed application development


Service Endpoint

ServiceEndpoints contain the ABCs of a service.

• EndpointAddress (A): A WCF service endpoint has a URI. EndpointAddress contains the URI, optional Address Headers and an optional Identity field (only useful when having multiple end points that shares the same URI)

• Binding (B): Bindings are a portion of the Policy that a service and consumer have to agree on if they want to exchange messages. This binding will contain the information to support the features being exposed by the service.

• ContractDescription (C): There are a number of different types of contracts with WCF. The primary contract that defines service is the service contract. This is analogous to the portType within WSDL today.


Binding

• Binding contains following information

• Name – Name of the binding

• Namespace – The namespace that makes the binding name unique

• BindingElements – A list of binding elements that defines different aspects of the expected binding


Exactly what does the binding tell us?

Bindings are capable of answering a number of questions about how a client and a service will communicate. Here are the key questions that are answered.

•What level of interoperability does this service have? • .NET to .NET or WS* specifications.

•What type of encoding is used? • Text, MTOM or Binary

•What type of transports can be used? • TCP, HTTP, Named Pipe, or MSMQ.

•What type of messaging patterns can be used? • Simplex, duplex, or request-reply.

•What type of security is supported? • Windows security, WS-Security, or transport level security.

•Is transaction flow supported? •Are reliable sessions supported?


Binding Elements

• A binding is a set of Binding Elements

• Types of Binding Elements• Transport Bindings – Binding which determines the transport

type (e.g. TCP, HTTP, MSMQ, etc.)

• Protocol Binding – The binding which process SOAP headers and implement protocols like (WS-Security, etc.)

• Example Bindings

Security Binding Element

ReliableSession Binding Element

TcpTransport Binding Element


Contract Description

• ContractDescription contains the following parts

• Name – Name of the service

• Namespace – The namespace that makes the service name unique

• OperationDescription – Descriptions of the operations (methods) of the service

• Message Description – Descriptions of the input and output messages of the service

• ContractBehavior – ContractBehaviors modifies or extend the behavior of the service contract


Service Description

• Services are described using ServiceDescriptions

• ServiceDescripion contsins

• ServiceType – The type that provide the service

• IServiceBehavior – The modifications or extensions to the service

• E.g. ServiceMetadataBehavior determines if the service publishes its metadata

• ServiceEndpoint – A set of ServiceEndpoints as discussed in previous slides (EndpointAddress, Binding and Contract)


Channels

• Channels are used by clients to communicate with services

• There are two types of channels• Transport Channels – Channels used to support transport mediums like TCP

• Protocol Channels – Channles used to support SOAP based protocols like WS-Security

• Generally a set of channels are used to access a given service endpoint

• Channels are described by ChannelDescriptions which contains,

• IChannelBehavior – Set of modifications or extensions to the channel behavior

• ServiceEndpoint – Service endpoints as discussed earlier


Service Configuration

• A configuration file entry of a service hosted in IIS or WAS is given below

<configuration> <system.serviceModel> <services> <service type="ServiceLibrary.EchoService"> <endpoint address="svc" binding="basicHttpBinding" contract="ServiceLibrary.IEchoService"/> <endpoint address="net.tcp://localhost:8081/echo/svc" binding="netTcpBinding" contract="ServiceLibrary.IEchoService"/> </service> </services> </system.serviceModel> </configuration>


Predefined Bindings

.Binding

Interop Encoding Transport Messaging Security Transaction Reliable

BasicProfile Basic Text HTTP, HTTPS

Request-reply, Simplex

Transport No No

WSProfile WS* Text, MTOM HTTP, HTTPS

Request-reply, Simplex

Transport, WS-Security

Yes Yes

WSProfileDualHTTP

WS* Text, MTOM HTTP Request-reply,

Simplex, Duplex

WS-Security Yes Yes

NETProfileTcp .NET Binary TCP Request-reply, Simplex

Transport, WS-Security

Yes Yes

NetProfileDualTcp .NET Binary TCP Request-reply,

Simplex, Duplex

WS-Security Yes Yes

NetProfileNamedPipe

.NET Binary Named pipe Request-reply,

Simplex, Duplex

Transport Yes No

NetProfileMsmq .NET Binary MSMQ Simplex Transport, WS-Security

Yes No

MsmqIntegration MSMQ Text MSMQ Simplex - Yes Yes

Intermediary - - HTTP, TCP, named pipe

- - - -


Instance Modes

• Single – Use a single instance to serve all the requests

• PerSession – New instance will be created per session

• PerCall – New instance will be created per request (method call)

• Shared – Instances will be pooled and shared


Service Interface

[ServiceContract(Name="EventsService)]

public interface IEventsService

{

[OperationContract(Name = "SaveEvent")]

void SaveEvent(LinkItem item);

[OperationContract(Name = "GetEvent")]

LinkItem GetEvent();

}


Implementing Interface

public class EventsService: IEventsService{ private LinkItem m_linkItem;

public void SaveEvent(LinkItem item) {

m_linkItem = item; }

public LinkItem GetEvent() {

return m_linkItem; }}


Data Contracts

[DataContract(Name="LinkItem")]public class LinkItem { [DataMember(Name="Id", IsRequired=false, Order=0)] private long m_id; [DataMember(Name = "Title", IsRequired = true, Order = 1)] private string m_title; [DataMember(Name="Desc", IsRequired = false, Order = 2)] private string m_desc;

public long Id { get { return m_id; }set { m_id = value; }

} public string Title { get { return m_title; } set { m_title = value; } } public string Description { get { return m_description; } set { m_description = value; } }}


Message Contracts

[MessageContract]public class SaveEventRequest{ private string m_licenseKey; private LinkItem m_linkItem;

[MessageHeader(MustUnderstand=true)] public string LicenseKey { get { return m_licenseKey; } set { m_licenseKey = value; } }

[MessageBody(Order=0)] public LinkItem LinkItem { get { return m_linkItem; } set { m_linkItem = value; } }}


Service Interface with Messages

[ServiceContract(Name="EventsService")]

public interface IEventsService

{

[OperationContract(Name = "SaveEvent")]

SaveEventResponse SaveEvent(SaveEventRequest message);

[OperationContract(Name = "GetEvent")]

GetEventResponse GetEvent(GetEventRequest message);

}


Hosting a Service in an Executable

• Services can be hosted in any executable

• These services can be configured• Directly by code• Using a configuration file (recommended)

• Configuring using code

ServiceHost sh = new ServiceHost(typeof(MathService)); sh.AddServiceEndpoint(

typeof(IMath), //contract type

new WSHttpBinding(), //one of the built-in bindings "http://localhost/MathService/Ep1" //the endpoint's address);

sh.Open(); //create and open the service runtime


WCF Clients

WCF can be written by using two techniques

• Direct CodeChannelFactory<IMath> factory = new ChannelFactory<IMath>(

new WSHttpBinding(),new

EndpointAddress("http://localhost/MathService/Ep1"));IMath channel = factory.CreateChannel();int result = channel.Add(35,7);factory.Close();

• Using ProxyMathProxy proxy = new MathProxy();int result = proxy.Add(35, 7);


Loggin Messages

• WCF can be configured to log its incoming and outgoing messages

• SvcTraceViewer tools can be used to analyze this data

copyright ©2004 virtusa corporation | confidential introduction to windows communication foundation...

Documents

windows security

service contract

expected binding slide

binding namespace

reply slide

wcf services

wcf service endpoint

uri binding b