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WCF Service Contracts

Create a WCF Service library project

  • Open Visual Studio
  • Select File > New > Project
  • Select WCF Service Library template under Visual C# > WCF templates
  • Change the name to ProductServiceLibrary and click OK
  • Visual studio will add reference to System.ServiceModel and System.Runtime.Serialization and will add some files with sample code. 
  • Delete IService1.cs and Service1.cs
  • Add a new class called ProductService
  • Add the following code. 
    [DataContract]
    public class ProductReview
    {
        [DataMember]
        public string Id { get; set; }
        [DataMember]
        public string ProductCode { get; set; }
        [DataMember]
        public string ProductName { get; set; }
        [DataMember]
        public string Review { get; set; }
    }

    [ServiceContract]
    public interface IProductService
    {
        [OperationContract]
        void SubmitReview(ProductReview pr);
    }

    [ServiceContract]
    public interface IReviewService: IProductService
    {
        [OperationContract]
        List<ProductReview> ListAllReview();
    }

  • Notice that there are multiple service contract
  • Further notice that IReviewService is derived from IProductService 
  • Now lets implement these service contract by adding the following code
     [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]
    public class ProductService : IProductService, IReviewService
    {
        List<ProductReview> Reviews = new List<ProductReview>();

        public void SubmitReview(ProductReview pr)
        {
            Reviews.Add(pr);
        }

        public List<ProductReview> ListAllReview()
        {
            return Reviews;
        }
    }
  • Modify the App.config by changing the name of service to IReviewService
  • Test the application 
  • Add a service host, as shown here.
  • Add a service client, as shown here. 
  • Run the host and client.
  • Test the application

Customizing Service Contract

  • Service contract can be customized
  • Let's customize [ServiceContract] and [OperationContract] of the IProductService as given below:
[ServiceContract(Name="SubmitReview", Namespace="http://www.sajega.com/service")]

[OperationContract(Name="Submit")]
  • Customize [ServiceContract] of the IReviewService as given below:
[ServiceContract(Name="SubmitReview", Namespace="http://www.sajega.com/service")]

[OperationContract(Name = "List")]

  • Note: Once you customize Service Contract & Operation Contract as given above you will need to update code in any service client that you may have already have. This is because the name of the Endpoint, client class and method names would have changed.

One-way operations

  • You can also make an operation one way. This allows the client to continue executing without waiting for the response. Let's make the SubmitReview operation a one-way operations by changing the [OperationContract] as shown below:
  • [OperationContract(Name="Submit", IsOneWay=true)]
  • Change the implementation of the SubmitReview operation as shown below:

        public void SubmitReview(ProductReview pr)
        {
            System.Threading.Thread.Sleep(5000);
            Reviews.Add(pr);
            Console.WriteLine("A new review was added");
        }

  • Run the program. Press 1 to add a review. Add all the field once you finish entering all the fields, notice that on the server the message takes 5 seconds to appear. But, on the client, the message "Thank you for your product review" appears almost instantly. 
  • Now remove IsOneWay = true, and build service. 
  • Updated ServiceReference on the client.  
  • Run the application.
  • Notice that confirmation on the client only appear just after the message in the server.

Exporting wsdl

  • Notice that in App.config file under serviceBehavior the httpGetEnabled is set to true. 
  • Open browser and browse to: http://localhost:8733/Design_Time_Addresses/ProductServiceW6/ProductService/
  • Notice the very first link is pointing to a wsdl definition, click it to see the wsdl definition

Download wsdl using SvcUtil.exe

  • Open developer command prompt
  • Navigate to the directory where you want to import the wsdl
  • type the following command: svcutil.exe t:metadata http://localhost:8733/Design_Time_Addresses/ProductServiceW6/ProductService/
  • notice that some files are created. one of them is wsdl definition.

Importing wsdl

  • In developer command prompt 
  • type the following command: svcutil.exe tempuri.org.wsdl tempuri.org.xsd schemas.microsoft.com.2003.10.Serialization.xsd
  • Notice that it gave you a ProductService.cs file and a output.config file
  • Open ProductService.cs file and notice it as the interfaces and  the proxy class. 


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