WCF Basic

WCF
- windows communication foundation (.net 3.0)
- communication framework
- enables us to expose CLR type services and consume exisitng services as CLR types
- Different communication technologies in the world - webservices (asmx), web services enhancements(wse), messaging (msmq), .net enterprise services (ES), .net remoting
- used for building service oriented applications
- eg: websevice for weather - consumes zip code and outputs forecast
- wcf service is based on contract ( implemented  as an interface decorated with the attribute [ServiceContractAttribute] )
[ServiceContract]
public interface IWeatherForecastService
{
    [OperationContract]
    public WeatherForecast GetForeCast(int zipCode);
}
- Address : where the service will be found [ServiceContract]
public interface IWeatherForecastService
{
    [OperationContract]
    public WeatherForecast GetForeCast(int zipCode);
}
ABC od WCF
- Address: where the service will be found scheme://domaon[:port]/path (e.g.: http://localhost:8080/MyWCFService ). 
- Binding :Protocols used by specific endpoint(http, tcp, msmq)
- Contract : Expresses what the service does (can have an app with multiple channels)
- Endpoint : combination of ABC
- Consumer of sevice creates a proxy. This Proxy is what the consumer uses to communicate with the host and basically is an empty type that exposes all operations in a service contract, and hides serialization/sending over wire details. A single proxy, uses a single endpoint.
- WeatherForecast type is a class we wrote and it represents a business object that conveniently holds all data related to the forecast. When sending this object to a consumer it will be serialized.
Conclusion: We have a host and client who agree upon a contract.  Our host exposes one or more EndPoints which are a combination of Address, Binding and Contract. On the other side our client uses a Proxy (this proxy is tied to a specified EndPoint thus also tied to a particular Contract). The actual communication related details are abstracted in Channels and Behaviors.
Ask these to yourself
   -  First, think of the contract (What am I trying to do?!)
   -  Secondly, think of where you will host it, and what technology you will use to host it.  
   -  Finally think of the other parts like authentication.
1. Create a 'WCF Service Application'
2. Add a new WCF Service file (.svc). [name.svc and Iname.cs will be created]
3. Add this in .cs file
namespace HelloWorldService
{
    [ServiceContract]
    public interface IHelloWorld
    {
        [OperationContract]
        string sayHello(string name);
    }
}
4. Add this in .svc file
namespace HelloWorldService
{
   public class HelloWorld : IHelloWorld
    {
        public string sayHello(string name)
        {
            return "Hello " + name;
        }
    }
}
5. We just can run the application and use the default bindings
6. To test the method we can also run WCF Test Client (in C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE) and pass value to the method. We can see the output in 2 formats - XML, formated

The request:
http://schemas.xmlsoap.org/soap/envelope/

">
 
            xmlns="http://schemas.microsoft.com/ws/2005/05/addressing/none">                 http://tempuri.org/IHelloWorld/sayHello>
 
 
    http://tempuri.org/">
      Jeroen
   
 
The response:http://schemas.xmlsoap.org/soap/envelope/
">
 
 
    http://tempuri.org/">
      Hello Jeroen
   
 

WCF CLIENT - will consume this service
client can be created
- by using metadata exposed by the EndPoint to generate proxies on the fly
- by pre-distribute the metadata as a definition of the interface, or a dll that contains the IHelloWorld interface.
1. Create a console app and add a refernce to our WCF service (add service refernce : address : http://localhost:5558/HelloWorld.svc
2. write
static void Main(string[] args)
{
    // Create a new HelloWorldClient object
    HelloWorldReference.HelloWorldClient client = new HelloWorldReference.HelloWorldClient();
    // Write the response from the sayHello method
    Console.WriteLine(client.sayHello("Jeroen"));
    // Close the WCF connection
    client.Close();
    Console.Read();
}



Types of Contracts / Services:
1. Service Contract : all operations that client can perform
2. Data Contract : defines data types that are passed in and out of service. [DataContract] and [DataMember] attributes are used
3. Fault Contract : describes the error raised by the service . [FaultContract(<>)] attribute is used
4. Message Contracts: direct control over SOAP message structure. This is useful in inter-operability cases and when there is an existing message format you have to comply with. [MessageContract], [MessageHeader], [MessageBodyMember] attributes are used



Example of Data Service:
- Microsoft implementation of OData, which is an open-format specification for accessing data
- Microsoft Visual Studio .NET facilitates creating a WCF data service by using an ADO.NET Entity Framework data model.
- WCF Data Services is designed to provide access to your data (xml, database,


A solution has a web application and a 'WCF Data Service'  file (exposed URI you can call from the internet)