WINDOWS COMMUNICATION FOUNDATION

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WINDOWS COMMUNICATION FOUNDATION

• www.otssolutions.com

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Agenda

• Introduction to WCF
• What is it Why use it
• Architecture
• Fundamentals and the ABCs of WCF
• Hosting
• Tooling Support
• Handling faults

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Introduction to WCF
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What is WCF

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

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Different technology combined to form WCF.
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WCF Architecture
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SOA

• Service
• Small program interacted by well defines message
  exchanges
• Agile Reliable Stable Interoperable Secure
• Four Tenets
• Boundaries are Explicit
• Services are Autonomous
• Services share schema and contract not class
• Service compatibility is based upon policy

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SOA solutions used
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SOA Use for Mobile platforms
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Windows Communication Foundation

• WCF provides
• an SDK for creating SOA
• a runtime for running Services on Windows
• Services send and receive messages
• All messages are SOAP messages
• WCF takes care of all the plumbing

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Why use WCF

• Interoperable and Standards based
• Supports WS- protocols
• Unified Programming Model
• Unifies previous models like .NET Remoting ASMX
  web services COM etc
• Productive Programming Model
• Declarative
• Imperative
• Configuration based

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WCF Value Proposition

• Simplicity
• Flexibility
• Maintainability
• Power

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WCF How does it work

• SOAP over HTTP
• SOAP over Message Queues
• SOAP over TCP

SOAP Message
Client
Service
SOAP Message
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WCF End points
A Address (Where) B Binding (How) C
Contract (What)
A
B
C
Client
Service
Message
A
B
C
A
B
C
A
B
C
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WCF Endpoints

• Every service has
• Address
• Where the service is
• Binding
• How to talk to the service
• Contract
• What the service can do

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Address

• Combination of transport server name port
  path
• Transport is determined by the binding
• Examples
• http//localhost8001
• net.tcp//localhost8002/MyService
• net.pipe//localhost/MyPipe
• net.msmq//localhost/private/MyService
• net.msmq//localhost/MyService

http//server345/Service
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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

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Out of the box Bindings

• BasicHttpBinding
• WSHttpBinding
• WS2007HttpBinding
• WSDualHttpBinding
• WSFederationHttpBinding
• WS2007FederationHttpBinding

• NetTcpBinding
• NetNamedPipeBinding
• NetMsmqBinding
• NetPeerTcpBinding
• WebHttpBinding
• MsmqIntegrationBinding

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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

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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()
...
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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
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Alternative DataContract

• DataContract created specifically for WCF to
  serialize types
• Attribute contains Name and Namespace properties
• DataMember is needed to specify which
  properties/fields will form part of the contract
• Contains EmitDefaultValue IsRequired Name
  Order properties

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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 points
• Bindings that are used
• Contracts used Service Operation Data etc

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Hosting

• IIS
• HTTP only
• WAS (Windows Activation Service)
• Can use any transport
• Vista and Windows Server 2008 only
• Self hosting
• Can use any transport
• Can be hosted within Console WinForms etc
  Applications

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Tooling Support
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Tooling Support

• Visual Studio
• Separate projects for WCF
• Add Service reference menu
• WCF Configuration Editor
• WCF Service Host
• WCF Test Tool
• SvcUtil To generate proxies
• SvcTraceViewer To view logs

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Handling Faults
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SOAP Faults

• Three main kinds of Exceptions can occur
• Communication errors
• Unexpected error on the service
• Errors thrown by the service on purpose
• .NET Exceptions are technology specific
• All Exceptions come across the wire as SOAP
  Faults

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Faults

• In WCF SOAP faults are passed in as
  FaultException objects
• Rather than throwing Exceptions services should
  throw FaultExceptions
• Or better still FaultExceptionltTgt
• Throwing FaultExceptions will not fault the proxy
  and the channel

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FaultContracts

• Specifies what kind of Exceptions an operation
  can throw

ServiceContract public interface
IEmployeeService OperationContract
FaultContract(typeof(ValidationException
)) public void AddEmployee(Employee e)

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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.

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Disadvantage

• WCF is Microsofts 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.

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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

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• Thank You

• http//www.otssolutions.com/

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