Create a dataContract in separe file problem - asp.net

Question

Hi I need to create a class for return the data in WCF service. I followed the web at 5 simple steps to create your first RESTful service. However I get the error for . I searched the web and add the System.Runtime.Serialization.DataContractSerializer, Would someone tell me what should do. I am using VS2015 as the tool to build it. Thanks.
Imports System.Runtime.Serialization
Imports System.Collections.Generic
Imports System.Runtime.Serialization.DataContractSerializer
<DataContract>
Public Class Locations
<DataMember>
Public Property LocationName As String
<DataMember>
Public Property LocationID As Integer
End Class

Answer 1

Could you please share the error details with me?
As you know, we usually use the datacontract to transmit the complex data type which could be recognized by the client-side and server-side. so that the data could be serialized and transmitted normally between different platforms.
For the restful web service in WCF, we need to use the Webhttpbinding build the data channel and add the Webhttpbehavior to the service endpoint.
I have made a demo, wish it is useful to you.
Server-side.
Imports System.Runtime.Serialization
Imports System.ServiceModel
Imports System.ServiceModel.Description
Imports System.ServiceModel.Web
Module Module1
Sub Main()
Dim uri As New Uri("http://localhost:900")
Dim binding As New WebHttpBinding()
binding.CrossDomainScriptAccessEnabled = True
binding.Security.Mode = WebHttpSecurityMode.TransportCredentialOnly
binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None
Using sh As New ServiceHost(GetType(MyService), uri)
Dim se As ServiceEndpoint = sh.AddServiceEndpoint(GetType(IService), binding, uri)
se.EndpointBehaviors.Add(New WebHttpBehavior())
sh.Open()
Console.WriteLine("Service is ready")
Console.ReadLine()
sh.Close()
End Using
End Sub
<ServiceContract([Namespace]:="mydomain")>
Public Interface IService
<OperationContract>
<WebGet(ResponseFormat:=WebMessageFormat.Json)>
Function SayHello() As List(Of Product)
End Interface
Public Class MyService
Implements IService
Public Function SayHello() As List(Of Product) Implements IService.SayHello
Dim result = New List(Of Product)() From {
New Product With {
.Id = 1,
.Name = "Apple"
},
New Product With {
.Id = 2,
.Name = "Pear"
}
}
Return result
End Function
End Class
<DataContract([Namespace]:="mydomain")>
Public Class Product
<DataMember>
Public Property Id() As Integer
<DataMember>
Public Property Name() As String
End Class
End Module
Client.
$(function(){
$.ajax({
type:"GET",
url:"http://10.157.18.188:900/sayhello",
dataType:"jsonp",
success:function(d){
$.each(d,function(i,o){
console.log(o.Id);
console.log(o.Name);
})
}
})
})
Result.
Here is an official sample
https://learn.microsoft.com/en-us/dotnet/framework/wcf/feature-details/how-to-create-a-basic-wcf-web-http-service