Dotnet3.5_WCF

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Confidential ©2009 Syntel, Inc.

WCF

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.NET 3.0

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Additive versions of the .NET Framework

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What Is WCF?

WCF is the Microsoft next generation technology for

developing distributed applications

WCF has been built to facilitate the development of service-

oriented applications

The communication between loosely coupled clients and

services is based on a model that uses schemas and

contracts, rather than classes and types

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Three Major Goals

What does WCF Solves?

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Why Handle Unification?

Current distributed technologies are based on different programming models

For example, if you are building an application that happens to communicateover HTTP, you will be required to change your programming model if you want

to switch to using TCP

If you are used to building XML web services today, you don’t have the ability to

support and flow transactions with message queuing enabled without changing

your programming model.

It avoids confusion by taking all the capabilities of the existing distributed

systems’ technology stacks and enables you to use one clean and simple API.

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WCF As a Service-Oriented Development Tool

Service orientation is not a technology but instead is a

design concept

Service orientation uses the best practices for building

today’s distributed applications

Although existing distributed technologies can offer the

groundwork for interoperability and integration, a newplatform was required—a new infrastructure that makes it

much easier to build these distributed technologies

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WCF As a Service-Oriented Development Tool

One of the challenges in developing WCF is shifting

developers’ mind-sets away from thinking about buildingdistributed systems in terms of objects and components and

starting to think about building distributed systems as

services.

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WCF Programming Model

SO or OO?

When developing WCF services, which do you use? Do you use a

service-oriented approach or an object-oriented approach to

developing a WCF solution?

The answer is, both.

Simply put, object-oriented programming is used to developapplications, and service-oriented programming is used to connect

those applications.

Think ―object-orientation = tightly coupled, and service-

orientation = loosely coupled.‖

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WCF Service from the outside

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WCF Service from the inside

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WCF Contracts

WCF contracts define the behavior of WCF services

They are created in code by service developers, and are exposed toclients in the service metadata

The five types of contracts:

Service Contracts

Operation Contracts

Data Contracts

Message Contracts

Fault Contracts

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Service Contracts

A service contract defines the operations that a service

supports, and maps to a portType in Web ServiceDescription Language (WSDL)

Service contracts are implemented as .NET Framework

interfaces that are annotated with the ServiceContract

attribute[ServiceContract]

public interface IBookOrder{ ...}

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Operation Contracts

Operation contracts define the individual operations that a

service supports and map to operations in WSDL

Operations are defined by adding methods to a Service

Contract interface that is annotated with the

OperationContract attribute

[OperationContract]void SomeOperation();

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Message Contracts

Message contracts provide a simple method to add custom

SOAP headers to incoming and outgoing messages

[MessageContract]

public class MyRequest {

[MessageHeader] public string field1;

[MessageBody] public string field2;}

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Fault Contracts

[OperationContract]

[FaultContract(typeof(DivideByZeroException))]void SomeMethod();

A Fault is generated by throwing a FaultException:

throw new

FaultException<DivideByZeroException>(someException);

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Example: Contract

[ServiceContract]

public interface IOrderService{

[OperationContract]void CreateOrder(int orderNumber);

[OperationContract]void AddItemToOrder(int orderNumber, Item itm);

[OperationContract]Order GetOrderDetails(int orderNumber);

}

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Example : Service

public class OrderService : IOrderService

{ void CreateOrder(int orderNumber){

// implementation details}

void AddItemToOrder(int orderNumber, Item itm){

// implementation details}

Order GetOrderDetails(int orderNumber){// implementation details

}}

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Example : Data Contract

[DataContract]

public class Order{

[DataMember]

public int OrderNumber;

[DataMember]public String ClientName;

...

}

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WCF Addresses

Service endpoints are exposed through addresses

Every endpoint must have an address so that other

programs can communicate with it

Windows Communication Foundation lets you use several

types of addresses to associate with each endpoint, and it is

through these addresses that the client communicates withthe endpoint

For example, an address might look like the following:

http://mymachine:8080/myservice

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WCF Bindings

A WCF binding is an object that specifies how to connect to

the endpoint of a WCF service, and each endpoint musthave a binding associated with it

WCF ships with a number of predefined bindings that cover

most common scenarios, although it is also possible to

create custom bindings

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What do Bindings Define?

A binding contains the following three categories of

information:1. Protocol information, such as the security mechanism that is being

used, and the reliable messaging and transaction settings

2. Information about the underlying transport protocol to use, such as

TCP or HTTP

3. Information about the message encoding, for example, Text or XML,

Binary, or Message Transmission Optimization Mechanism (MTOM)

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What do Bindings Define?

Bindings contain a collection of binding elements, such as

SecurityBindingElement and TcpTransportElement, whichdefine a communication stack, and the operation of the

stack depends on the order in which the binding elements

were added to the collection

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Predefined WCF Bindings

Binding information can be complex, and not all options may be

compatibleFor this reason, WCF provides a set of predefined combinations of

binding elements that are appropriate for many common scenarios

For example, BasicHttpBinding enables basic Web service

communication by using text or HTML, with WSHttpBinding also

supporting many of the WS-* standardsNote: Bindings are covered in details later

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Specifying Bindings

All types of bindings, including custom or predefined, can be

specified in configuration files or in code

By defining bindings in code, the developer gains complete

control over the definition at design time, but by specifying

binding information in configuration files, the binding

information can be changed without recompiling the code

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Service Configuration in WCF

WCF services can be configured in code or by using

configuration files

If you are hosting a service in IIS, you use the web.config

file, but you use the application configuration file for any

other application

Each service must have an endpoint defined

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Service Configuration in WCF

An endpoint consists of an address that shows where the

endpoint is located, a binding that specifies communicationinformation, and a service contract that identifies the

methods that the service supports

An endpoint address contains a URI as well as other

optional properties, such as an identity, WSDL elements,and headers

The optional properties can be used for tasks, such as

routing incoming messages or deciding where to send a

reply

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Defining Endpoints in Configuration Files

To set up endpoints in configuration files, define <endpoint>

elements within a parent <service> element inside the<system.ServiceModel> section of your configuration file

<endpoint

address="http://localhost/MathService/Ep1"

binding="wsHttpBinding"contract="IMath"/>

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Demo – Creating a WCF Service

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Options for Hosting a WCF Service

WCF is flexible because its services can be hosted in

different types of applications

The following lists several common scenarios for hosting

WCF services:

IIS

WAS Self-hosting

Managed Windows Service

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