Create a WCF Web Service in Visual Studio 2015

WCF (Windows Communication Foundation) is still widely used in legacy enterprise applications, especially when systems need SOAP/XML or lightweight REST services. In this article, we will learn how to create a REST-based WCF Web Service using JSON in Visual Studio 2015.

We will cover:

✔ Creating a WCF Service
✔ Writing a POST API method
✔ Accepting JSON input
✔ Returning JSON output
✔ Configuring web.config for REST/JSON
✔ Using DataContract / DataMember
✔ Working sample code

Step 1: Create a New WCF Application in Visual Studio 2015

Open Visual Studio 2015
Go to File → New → Project
Select
Visual C# → WCF → WCF Service Application
Name the project (Example: CholaWcfService)
Click OK

This creates:

Service1.svc
Service1.svc.cs
IService1.cs
web.config

Step 2: Modify IService1.cs

We want our API to accept JSON input and return JSON output, so we use:

[OperationContract]
[WebInvoke]
webHttpBinding

IService1.cs

using System.IO;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;

namespace CholaWcfService
{
    [ServiceContract]
    public interface IService1
    {
        [OperationContract]
        [WebInvoke(
            Method = "POST",
            RequestFormat = WebMessageFormat.Json,
            ResponseFormat = WebMessageFormat.Json,
            BodyStyle = WebMessageBodyStyle.Bare,
            UriTemplate = "/Payments"
        )]
        Stream Payments(RootObject request);
    }
}

Step 3: Create the Data Contract Class

DataContract and DataMember must be used for WCF JSON model binding.

[DataContract]
public class RootObject
{
    [DataMember]
    public string data { get; set; }

    [DataMember]
    public string details { get; set; }

    [DataMember(Name = "event")]
    public string Event { get; set; }

    [DataMember]
    public payload payload { get; set; }

    [DataMember(Name = "Bank Account Number")]
    public string bankaccountnumber { get; set; }

    [DataMember(Name = "Client Id")]
    public string clientcode { get; set; }

    [DataMember(Name = "Description")]
    public string description { get; set; }
}

Step 4: Implement the Service Method (Service1.svc.cs)

This method accepts JSON, processes it, and returns JSON as string inside a Stream.

Service1.cs

using System;
using System.Configuration;
using System.IO;
using System.ServiceModel.Web;
using System.Text;

public class Service1 : IService1
{
    string strcon = ConfigurationManager.ConnectionStrings["cholaPortfolio"].ToString();

    public Stream Payments(RootObject request)
    {
        try
        {
            string jsonResponse = "{\"status\":\"success\",\"message\":\"Payment processed\"}";

            WebOperationContext.Current.OutgoingResponse.ContentType = "application/json";
            return new MemoryStream(Encoding.UTF8.GetBytes(jsonResponse));
        }
        catch (Exception ex)
        {
            string errorResponse = "{\"status\":\"Error\",\"message\":\"" + ex.Message + "\"}";

            WebOperationContext.Current.OutgoingResponse.ContentType = "application/json";
            return new MemoryStream(Encoding.UTF8.GetBytes(errorResponse));
        }
    }
}

Step 5: Configure web.config for WCF JSON REST API

Replace or update with the following configuration:

Required Changes

Your current config is missing 3 important sections:

1. <endpointBehaviors> with <webHttp />
2. <endpoints> using webHttpBinding
3. behaviorConfiguration="jsonBehavior"

<configuration>

  <connectionStrings>
    <add 
      name="cholaPortfolio" 
      connectionString="Data Source=SoftSQL;Initial Catalog=testdb;Connect TimeOut=120; Max Pool Size=10000; user id=sa; password=capmark@09" 
      providerName="System.Data.SqlClient" />
  </connectionStrings>

  <system.web>
    <compilation debug="true" targetFramework="4.5.2"/>
    <httpRuntime targetFramework="4.5.2"/>
  </system.web>

  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <serviceMetadata httpGetEnabled="true" httpsGetEnabled="true"/>
          <serviceDebug includeExceptionDetailInFaults="true"/>
        </behavior>
      </serviceBehaviors>

      <endpointBehaviors>
        <behavior name="jsonBehavior">
          <webHttp />
        </behavior>
      </endpointBehaviors>
    </behaviors>

    <services>
      <service name="CholaWcfService.Service1">
        <endpoint 
            address=""
            binding="webHttpBinding"
            contract="CholaWcfService.IService1"
            behaviorConfiguration="jsonBehavior"/>
      </service>
    </services>

    <protocolMapping>
      <add binding="basicHttpsBinding" scheme="https"/>
    </protocolMapping>

    <serviceHostingEnvironment 
        aspNetCompatibilityEnabled="true" 
        multipleSiteBindingsEnabled="true"/>
  </system.serviceModel>

</configuration>

Step 6: Test in Postman

URL

http://localhost:port/Service1.svc/Payments

Method

POST

Headers

Content-Type: application/json

Sample JSON Body

{
  "data": "123",
  "details": "Testing",
  "event": "payment.received",
  "Bank Account Number": "1234567890",
  "Client Id": "CL001",
  "Description": "Payment API test"
}

Response

{
  "status": "success",
  "message": "Payment processed"
}