Getting error while running Service

I have created WCF service but while running the service I am getting below error: Error:

Failed to add a service. Service metadata may not be accessible. Make sure your service is running and exposing metadata.

Error Details:

Warning: No code was generated.If you were trying to generate a client, this could be because the metadata documents did not contain any valid contracts or servicesor because all contracts/services were discovered to exist in /reference assemblies. Verify that you passed all the metadata documents to the tool.Warning: If you would like to generate data contracts from schemas make sure to use the /dataContractOnly option.

Code:

namespace WCFTest
{
    [ServiceContract]
    public class EmployeeDetails
    {
        [OperationContract]
        public List<Employee> GetDetails()
        {
            List<Employee> emp = new List<Employee>()
            {
               new Employee(){Fname="AA",Lname="BB",EmpId=1,Desg="A"},
               new Employee(){Fname="CC",Lname="DD",EmpId=1,Desg="B"},
               new Employee(){Fname="EE",Lname="FF",EmpId=1,Desg="C"},
               new Employee(){Fname="GG",Lname="HH",EmpId=1,Desg="D"},
               new Employee(){Fname="II",Lname="JJ",EmpId=1,Desg="A"},
               new Employee(){Fname="KK",Lname="LL",EmpId=1,Desg="B"}
            };
            return emp;
        }
    }

    // Use a data contract as illustrated in the sample below to add composite types to service operations.
    [DataContract]
    [KnownType(typeof(Employee))]
    public class Person
    {
        [DataMember]
        public string Fname { get; set; }
        [DataMember]
        public string Lname { get; set; }
    }

    [DataContract]
    public class Employee : Person
    {
        [DataMember]
        public int EmpId { get; set; }
        [DataMember]
        public string Desg { get; set; }
    }
}

namespace WCFTest
{
    // NOTE: You can use the "Rename" command on the "Refactor" menu to change the class name "Ser开发者_Python百科vice1" in code, svc and config file together.
    public class Service1
    {
        public List<Employee> GetData(int value)
        {
            EmployeeDetails ed = new EmployeeDetails();
            return ed.GetDetails();
        }
    }
}

However I could see metadata is exposed in web.config.

Web.config:

<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
          <serviceMetadata httpGetEnabled="true"/>
          <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
 <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>
</configuration>

Any clue where I am going wrong?

EDIT: I think the reason behind the error is I am using a class as a service contract, now when I change it to an Interface, things work as expected, not sure why I am getting the error if I am specifying the class as service contract.

I don't see any <services> node in your config - you're not configuring a service at all - so there's nothing there to connect to.

You need to extend your config to include something like this:

<configuration>
  <system.serviceModel>

    <services>
      <service name="WCFTest.EmployeeDetails">
         <endpoint name="Default" 
                   address="/default"
                   binding="basicHttpBinding" bindingConfiguration=""
                   contract="WCFTest.EmployeeDetails" />
         <endpoint kind="mexEndpoint" address="/mex" />
      </service>
    </services>

  </system.serviceModel>
</configuration>

Now, you have a service with a service and a metadata endpoint, and now your WCF Test Client should be able to find something to connect to....