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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