WINDOWS COMMUNICATION FOUNDATION

WINDOWS COMMUNICATION FOUNDATION

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Agenda

Introduction to WCFWhat is it? Why use it?Architecture Fundamentals and the ABCs of WCFHosting

Tooling Support Handling faults

Introduction to WCF

What is WCF?

Stands for Windows Communication Foundation One of the 4 pillars of .NET 3.0 Microsoft’s unified programming model (the service model) for building Service-Oriented Applications

Different technology combined to form WCF.

WCF Architecture

SOA

ServiceSmall program interacted by well defines

message exchangesAgile, Reliable, Stable, Interoperable, Secure

Four TenetsBoundaries are ExplicitServices are AutonomousServices share schema and contract, not classService compatibility is based upon policy

SOA solutions used

SOA Use for Mobile platforms

Windows Communication Foundation WCF provides:

an SDK for creating SOAa runtime for running Services on

Windows Services send and receive messages All messages are SOAP messages WCF takes care of all the plumbing

Why use WCF?

Interoperable and Standards basedSupports WS-* protocols

Unified Programming ModelUnifies previous models like .NET

Remoting, ASMX web services, COM+ etc Productive Programming Model

Declarative ImperativeConfiguration based

WCF Value Proposition Simplicity Flexibility Maintainability Power

WCF: How does it work?

WCF End points

WCF Endpoints

Every service has Address

Where the service is Binding

How to talk to the service Contract

What the service can do

Address

Combination of transport, server name, port & path

Transport is determined by the bindingExamples

http://localhost:8001net.tcp://localhost:8002/MyServicenet.pipe://localhost/MyPipenet.msmq://localhost/private/MyServicenet.msmq://localhost/MyService

Bindings

Transport HTTP TCP MSMQ

Message formats and encoding Plain text Binary Message Transmission Optimization Mechanism

(MTOM) Communication security

No security Transport security Message security Authenticating and authorizing callers

Out of the box Bindings

BasicHttpBinding WSHttpBinding WS2007HttpBinding WSDualHttpBinding WSFederationHttp

Binding WS2007FederationHttp

Binding

NetTcpBinding NetNamedPipeBinding NetMsmqBinding NetPeerTcpBinding WebHttpBinding MsmqIntegrationBinding

Contracts

Service contracts Defines operations, communications

and behaviours. Data contracts

Defines data entities and parameter types.

Fault contracts Defines error types

Message contracts Defines message formats

Service Contracts

[ServiceContract] – Defines a ‘set’ of operations [OperationContract] – Defines a single method

[ServiceContract]public interface IService{ [OperationContract] string GetData(int value);}

public class ConcreteService : IService{ public string GetData(int value) { ... }

public string OtherMethod() { ... }}

[ServiceContract]public interface IService{ [OperationContract] string GetData(int value);}

public class ConcreteService : IService{ public string GetData(int value) { ... }

public string OtherMethod() { ... }}

Data Contracts

[DataContract] – Specifies type as a data contract [DataMember] – Members that are part of

contract

[DataContract]public class CustomType{ [DataMember] public bool MyFlag { get; set; }

[DataMember] public string MyString { get; set; }

}

[DataContract]public class CustomType{ [DataMember] public bool MyFlag { get; set; }

[DataMember] public string MyString { get; set; }

}

Alternative – DataContract

DataContract: created specifically for WCF to serialize typesAttribute contains Name and Namespace

properties DataMember is needed to specify which

properties/fields will form part of the contractContains EmitDefaultValue, IsRequired,

Name, Order properties

Metadata Exchange

Service can also expose endpoint for Metadata Exchange (MEX)

It provides a mechanism for clients to find out about:Address of other end pointsBindings that are usedContracts used – Service, Operation, Data,

etc

Hosting

IISHTTP only

WAS (Windows Activation Service)Can use any transportVista and Windows Server 2008 only

Self hostingCan use any transportCan be hosted within Console, WinForms,

etc Applications

Tooling Support

Tooling Support

Visual StudioSeparate projects for WCF“Add Service reference” menuWCF Configuration EditorWCF Service HostWCF Test Tool

SvcUtil – To generate proxies SvcTraceViewer – To view logs

Handling Faults

SOAP Faults

Three main kinds of Exceptions can occur:Communication errorsUnexpected error on the serviceErrors thrown by the service on purpose

.NET Exceptions are technology specific All Exceptions come across the wire as SOAP

Faults

Faults

In WCF, SOAP faults are passed in as FaultException objects

Rather than throwing Exceptions, services should throw FaultExceptions

Or better still FaultException<T> Throwing FaultExceptions will not fault the

proxy and the channel

FaultContracts

Specifies what kind of Exceptions, an operation can throw

[ServiceContract] public interface IEmployeeService { [OperationContract] [FaultContract(typeof(ValidationException))] public void AddEmployee(Employee e); }

[ServiceContract] public interface IEmployeeService { [OperationContract] [FaultContract(typeof(ValidationException))] public void AddEmployee(Employee e); }

Advantage Its made of a lot of different components, so you can

create new components for security, transport, authentication.

In WCF, there is no need to make much change in code for implementing the security model and changing the binding. Small changes in the configuration will make your requirements.

Its faster than ASMX Its Interoperability, for java, and more. WCF is interoperable with other services when

compared to .Net Remoting, where the client and service have to be .Net

WCF services provide better reliability and security in compared to ASMX web services.

Disadvantage WCF is Microsoft's implementation of SOA and

hence its APIs are solely controlled by MS which makes interoperability a bit difficult.

To deploy WCF apps, need more underlying hardware resources on the platform on which the WCF applications will be running, since there is an additional layer of abstraction to deal with.

Summary

WCF provides a runtime for creating Service Oriented Apps Provides a productive programming model. Takes care of:

Messaging and Exchange formats All Plumbing: Transaction, Reliability, Security, etc

Supports Declarative (via attributes), Imperative (via code) and Configuration based (via config files) programming model

ABCs of Endpoints Address: Where to go? Binding: How to get there? Contract: What to do?

Hosting IIS, WAS, Self-hosting

Thank You

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