WCF - An Introduction

8/3/2019 WCF - An Introduction

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Deepak SinghviAbans Technologies

WindowsCommunicationFoundation (WCF 3.5)

07 Jun 2010



Agenda

Introduction

Overview Contracts

Bindings

Behaviours Summary



Introduction



From Objects to Services

Polymorphism

Encapsulation

Subclassing

Message-based

Schema+Contract+Policy

Broad Interop

Location Transparent

Tight Coupling

Runtime Metadata

Object-Oriented Service-OrientedComponent-Oriented

1980s 2000s1990s



Four tenants of Service Orientation

SERVICE ORIENTATION

Compatibility Based On Policy

Share Schema & Contract, Not Class

Services Are Autonomous

Boundaries Are Explicit



So What’s new

“Client”

“Service” Extensibility

Metadata

Standards Support

Unified Capabilities

Programming Model



Windows Communication Foundation

PRODUCTIVITYINTEROPERABILITY SERVICE-ORIENTEDDEVELOPMENT

• Broad Support for WS-* specifications

• Compatible with

existing MS distributedapplicationtechnologies

• Unifies today’sdistributed technologies

• Attribute-baseddevelopment

• Visual Studio 2005integration

• Enables developmentof loosely-coupledservices

• Config-basedcommunication



WCF

The next-generation platform for distributed systems

A pillar of the Microsoft.NET Framework 3.0

Build WCF services in Visual Studio 2005 using any .NETLanguage

– Intelligent code editing, IDE Extensions for WCF, debugging, re-factoring, code snippets, etc.

Runs on

– Microsoft Windows Vista

– Microsoft Windows XP

– Microsoft Windows Server 2003

Codename “Indigo”



WCF – Message based communication

“Client”

“Service”



Overview



What is WCF

Unification of Technologies – Abstraction of service code from the transport layer

Interoperability – WS-* specification support

Service-Oriented Development – Loose Coupling

Developer efficiency – Configuration file based

– Attribute based



Widows Communication Foundation

ASMX

Attribute-

Based

Programming

EnterpriseServices

WS-*

Protocol

Support

Message-

Oriented

Programming

System.Messaging

.NETRemoting

Interop

with other

platforms

Extensibility

Location transparency

WSE

Fast,Secure,Binary

Basic,Open Comm

Secure,O en Comm

Fast,

Secure,Binary,Txns

MSMQ,Queued, Txns



Conventional Web Services

The old way of easily exposing components (ASMX):

.NET Component

ASMX Web Service

HTTP Client



WCF Services

The new way of easily exposing components (WCF):

.NET Component

HTTP Host TCP Host ICP Host MSMQ Host

HTTP Client TCP Client ICP Client MSMQ Client

Service Contract



WCF – Standard Support ( Protocol

support)

XML

Messaging M e t a d a

t aSecurity

ReliableMessagin

g

Transactions



Messaging (WS-Addressing):- SOAP is the fundamental protocol for web services. WSAddressing defines some extra additions to SOAP headers, which makes SOAP free fromunderlying transport protocol. One of the good things about Message transmission isMTOM, also termed as Message Transmission Optimization Mechanism. They optimize

transmission format for SOAP messages in XML-Binary formant using XML optimizedpackaging (XOP). Because the data will sent in binary and optimized format, it will give ushuge performance gain.

Security (WS-Security, WS-Trust, and WS-Secure Conversation):- All the three WS- defineauthentication, security, data integrity andprivacy features for a service.

Reliability (WS-Reliable Messaging):- This specification ensures end-to-end communicationwhen we want SOAP messages to be traversed back and forth many times.

Transactions (WS-Coordination and WS-Atomic Transaction):- These two specifications

enable transaction with SOAP messages. Metadata (WS-Policy and WS-Metadata exchange):- WSDL is a implementation of WS-

Metadata Exchange protocol. WS-Policy defines more dynamic features of a service, whichcannot be expressed by WSDL.



Client

Binding(ordered list of channel types & config)

channel typeN

channel type 2

channel type 1config

config

config

Your code

Service

Your code M e t a d a t a

objects XML

formatting

channel

channel

channel

Transport Channel (HTTP, TCP, MSMQ, Pipes, Peer)

channel

channel

channel

decodingencoding

behaviours behaviours

Overall Architecture



Main Goal

Unification

– Unify today’s distributed technology stacks

– Talk on-machine, cross-machine, cross-networks & Internet

Productivity

– Codify best practices for building distributed apps

– Maximize productivity

Integration – Interoperate with apps running on other platforms

– Integrate with Microsoft’s existing technologies



Callers and Services

Caller Service



Caller Service

Endpoints

Endpointndpoint

Endpoint

Endpoint



Service

C

C

Caller

Address, Binding, Contract

A

Address

Where?

Contract

What?

Binding

How?

C



ABC’s of WCF – Address, Binding, Contract

Three levels of abstraction expressed in WSDL

Address – Location of the service

– Uri

– Can be dynamic

Binding – How to talk to the service

– Programmatic or config file based

Contract – What the service does

– Interface based



Service

Service Host

Caller

Creating Endpoints

Proxy or

ChannelFactory

A C

C

C



proxy.cs

Caller

app/web.config

Exposing & Configuring Endpoints

GetMetadata

WSDL

Service

C

C

C

C

C

?



Address

Consists of:

–

Protocol – Server Name

– Port

– Path

Logical address does not have map to aphysical file, except in IIS



Contract A collection of operations that specifies what the Endpoint communicates to the outside

world Identified by Name and Namespace Duplex Contracts

– Server can call client – WSDualHttpBinding

Data and Service components

There are three types of contracts – Service Contracts

Describe the operations a service can perform

Map CLR types to WSDL – Data Contracts Describes a data structure Maps CLR types to XSD

– Message Contracts Defines the structure of the message on the wire Maps CLR types to SOAP messages



Bindings

Specification of how the client and server willcommunicate

Multiple endpoints possible for a service

Predefined Bindings

– Configuration file based

Custom Bindings



Predefined Bindings

BasicHttpBinding

WSHttpBinding

WSDualHttpBinding WSFederationBinding

NetTCPBinding

NetPeerTCPBinding

NetNamedPipeBinding NetMsmqBinding

MsmqIntegrationBinding



Creating a Service

Create the contract

–

Interfaces and implementations Data Contracts

Service Contracts

Host the service

Configure bindings Create a client



Contracts



Service Contract

[ServiceContract]

public interface ICalculator

{

[OperationContract]

int DoMath(int a, int b, string op);

}



Service Contract

An Opt-In Model

[ServiceContract]

public interface ICalculator

{

[OperationContract]

int DoMath(int a, int b, string op);

// Not exposed as part of the external contract :-)

void MethodRequiredForImplementation(bool b);

}



Operations Types

Message DoXmlMath(Message m);

Untyped (“Universal”)

MathResponse DoMsgMath(MathRequest msg);

int DoParamsMath(int a, int b, string op);

Typed Message

Parameterized Operations



Service Contract: Names

[ServiceContract(Namespace="http://TechEd.WCF.Intro")]

public interface IGreetings{[OperationContract( Name=“SayHello",

Action="http://TechEd.WCF.Intro/HelloRequest",

ReplyAction="http://TechEd.WCF.Intro/HelloResponse"

string Greet(string name);

[OperationContractAttribute(Action = "*")]

void UnrecognizedMessageHandler(Message msg);

}



Service Contract: Names contd

class GreetingService : IGreetings

{public string Greet(string name)

{

return “Hello, " + name;

}

public void UnrecognizedMessageHandler(Message msg){

Console.WriteLine("Unrecognized message: " +msg.ToString());

}}



Modeling Request/Reply

Operations

On the wire everything is asynchronous

Therefore, Request and Reply correlation can be modeled in 2 ways

It can be modeled either as a synchronous (blocking) method call

or using the .NET Async-Pattern

The implementation on the client and the service can be different!

[OperationContract]

MathResponse DoMsgMath(MathRequest msg);

[OperationContract(AsyncPattern=true)]

IAsyncResult BeginDoMsgMath(MathRequest msg,

AsyncCallback cb, object state);

MathResponse EndDoMsgMath(IAsyncResult call);



Service Contract: OneWay

[ServiceContract]

public interface IOneWayCalculator{

[OperationContract(IsOneWay=true)]

void DoMath(MathRequest request);

}



Service Contract: Duplex

[ServiceContract(SessionMode=SessionMode.Required,

CallbackContract=typeof(ICalculatorResults)]public interface ICalculatorProblems

{


void DoMath(MathRequest request);

}

public interface ICalculatorResults

{


void DisplayResults(MathResponse response);}



Service Contract: Faults

try{return n1 / n2;}

catch (DivideByZeroException e) {

MyMathFault f = new MyMathFault (n1, n2);

FaultReason r = new FaultReason("Divide By Zero");

throw new FaultException<MyMathFault>(f, r);}

[ServiceContract(Session=true)]

public interface ICalculator{

[OperationContract][FaultContract(typeof(MyMathFault))]

int DoMath(int a, int b, string op);}



Data Contract

[DataContract]

public enum Position

{[EnumMember]

Employee,

[EnumMember]

Manager,[EnumMember(Value = “Vendor")]

Contractor,

NotASerializableEnumeration

}



Data Contract: Names

[DataContract(Name=“Complex”, Namespace=“http://BigMath.Samples”)]

public class ComplexNumber{

[DataMember(Name=“RealPart”)]public double Real = 0.0D;[DataMember(Name=“ImaginaryPart”)]public double Imaginary = 0.0D;

public ComplexNumber(double r, double i){

this.Real = r;this.Imaginary = i;

}

}



Data Contract: Enumerations

[DataContract]

public enum Position

{[EnumMember]

Employee,

[EnumMember]

Manager,[EnumMember(Value = “Vendor")]

Contractor,

NotASerializableEnumeration

}



Message Contract

[MessageContract]

public class ComplexProblem

{[MessageHeader(Name="Op", MustUnderstand=true)]public string operation;

[MessageBodyMember]public ComplexNumber n1;

[MessageBodyMember]public ComplexNumber n2;

[MessageBodyMember]public ComplexNumber solution;

// Constructors…

}



Bindings



Bindings & Binding Elements

Transport

IPCSMQ

Custom

TCP HTTP

ProtocolEncoders

.NETX

Custom

Security Reliability

Binding

HTTP TXecurity Reliabilityext

Text

Binary

Custom

TCP

Binary



Binding Element Features

Transport selection – TCP, HTTP, Named Pipes, P2P, MSMQ, Custom – Transport level security, Streaming

Encoding – Text, Binary, MTOM, Custom

End-to-end Security – Confidentiality, integrity, authN, authZ, Federation – Credentials: X509, User/Pwd, Kerberos, SAML, InfoCard , Custom

End-to-end Reliable messaging – Transport independent QoS (in order, exactly once) – Volatile and durable queues

Transactions – Shared transactions for “synchronous” operations – Transactional queues for “asynchronous” operations

[Your own feature goes here]



System-Provided BindingsBinding Interop Security Session TX Duplex

BasicHttpBinding BP 1.1 N, T N N n/a

WSHttpBinding WS M, T, X N, T, RS N, Yes n/a

WSDualHttpBinding WS M RS N, Yes Yes

WSFederationBinding Federation M N, RS N, Yes No

NetTcpBinding .NET T, M T ,RS N, Yes Yes

NetNamedPipeBinding .NET T T, N N, Yes Yes

NetPeerTcpBinding Peer T N N Yes

NetMsmqBinding .NET T, M, X N N, Yes No

MsmqIntegrationBinding MSMQ T N N, Yes n/a

N = None | T = Transport | M = Message | B = Both | RS = Reliable Sessions



Binding in Config

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

<system.serviceModel>

<services>

<service serviceType="CalculatorService">

<endpoint address="Calculator"

bindingSectionName="basicProfileBinding"

contractType="ICalculator" /></service>

</services>

</system.serviceModel>

</configuration>



Configuring Bindings

<endpoint address="Calculator"bindingSectionName="basicHttpBinding"bindingConfiguration="UsernameBinding"

contractType="ICalculator" />

<bindings><basicHttpBinding>

<binding name="UsernameBinding"

messageEncoding="Mtom">

<security mode="Message">

<message clientCredentialType="UserName"/>

</security>

</binding>

</basicHttpBinding>

</bindings>



Custom Bindings

<bindings>

<customBinding>

<customBinding>

<binding name="ReliableTCP">

<reliableSession inactivityTimeout="0:0:5“

ordered="true"/>

<binaryMessageEncoding/>

<tcpTransport transferMode="Buffered"/>

</binding>

</customBinding>

</customBinding>

</bindings>



Choosing Bindings

WCF WCF Any Protocol Any

Binding

Any

Binding

MSMQ WCF

COM+/ES WCF

MSMQ Protocol

WS-* Protocols

MSMQ

Binding

Moniker

ASMX/WSE3 WCF WS-* ProtocolsHttp/WS

Binding

Other Platform WCF WS-* ProtocolsHttp/WS

Binding



Interaction of Bindings and Code

Bindings provide features that affect code

– Session

– Duplex

– Ordered Delivery

– Transaction Flow

– Queued Delivery Attribute capture the code’s requirements

Infrastructure ensures that all the bindingssatisfy these requirements



WCF Instance Creation Following are different ways by which you would like to create

WCF instances:- – You would like to create new WCF service instance on every WCF

client method call. – Only one WCF service instance should be created for every WCF

client session. – Only one global WCF service instance should be created for all

WCF clients.

To meet the above scenarios WCF has provided 3 ways by

which you can control WCF service instances:- – Per Call – Per session – Single instance





Per Call instance mode[ServiceBehavior

(InstanceContextMode =InstanceContextMode.Percall

]

public class Service : IService{

private int intCounter;

public int Increment(){

intCounter++return intCounter;

}}



Per session Instance mode

[ServiceBehavior

(InstanceContextMode =InstanceContextMode.PerSes

sion)]public class Service : IService

{


public int Increment()

{

intCounter++

return intCounter;

}

}



Single Instance mode

[ServiceBehavior

(InstanceContextMode =InstanceContextMode. Single

)]public class Service : IService

{


public int Increment()

{

intCounter++

return intCounter;

}

}



When should you use per call, per session andsingle mode?

Per call – You want a stateless services – Your service hold intensive resources like connection object and huge

memory objects. – Scalability is a prime requirement. You would like to have scale

out architecture . – Your WCF functions are called in a single threaded model.

Per session – You want to maintain states between WCF calls. – You want ok with a Scale up architecture.

– Light resource references Single

– You want share global data through your WCF service. – Scalability is not a concern.





Behaviours



Behaviors

Client-SideBehaviors

Service-SideBehaviors

Service

C

C

Caller

A

C

BeBe



Behaviors: Overview

Behaviors are all local

Developers care about some behaviors

– Concurrency, instancing model, …

– Everything that affects the correctness of the service

Deployers care about other behaviors

– Throttling, Metadata exposure, message routing info,

… – Everything that has to do with the service’s runtime

aspects

Anything you can do in config, you can do in code

– Code is King – you can always override the config



Example: Security

Service

C

C

Client

A

C

BeBe

Bindings MoveClaims in

Messages

BehaviorsImplement

Security Gates

Behaviors ProvideCredentials



Example: Transactions

Service

C

C

Caller

A

C

Be

Bindings FlowTransactions

BehaviorsAutoEnlist andAutoComplete



Anti-Example:

Reliable Sessions

Service

C

C

Caller

A

C

Bindings provideSession andGuarantees



Behavior Features

Operation timeouts (close, open, idle)

Concurrency, Instancing, Thread-Binding

Throttling

Faults, Exceptions

Impersonation, Authorization, Auditing

AutoEnlist, AutoComplete, Timeout, Isolation Serialization, MustUnderstand

Metadata

More…



WCF Summary

Address Binding BehaviorContractHTTP

Transport

TCP

Transport

NamedPipeTransport

MSMQTransport

CustomTransport

WS-SecurityProtocol

WS-RMProtocol

WS-ATProtocol

DuplexChannel

CustomProtocol

http://...

net.tcp://...

net.pipe://...

net.msmq://...

xxx://...

Throttling

Behavior

MetadataBehavior

ErrorBehavior

CustomBehavior

InstancingBehavior

ConcurrencyBehavior

TransactionBehavior

SecurityBehavior

Request/Response

One-Way

Duplex

net.p2p://...

Peer

Transport

Externally visible, per-endpoint Opaque, per-service, endpoint, or op



WCF Application “Architecture”

Channels

Transport Channels

(IPC, HTTP, TCP…) Reliability

Message

EncoderSecurity

Hosting Environments

Instance

Manager

Context

Manager

Type

Integration

Service

Methods

Declarative

Behaviors

Transacted

Methods

WASIIS .exe

Windows

Service DllHost

Messaging Services

Queuing Routing Eventing Discovery

Service Model

Application



Presentation Takeaways

WCF is the future of distributed computing

It combines the best of all existing Microsoft distributed computingstacks

It uses WS-* standards for interoperability and .NET value-add forperformance and integration with existing solutions

WCF is available for Windows Vista, Windows XP SP2, WindowsServer 2003



Thank You

[email protected]

[email protected]

mailto:[email protected]

mailto:[email protected]

Documents

WCF - An Introduction