C#

using System.ServiceModel;
using System.ServiceModel.Web;

namespace PERFoRM_LhnetRESTServiceHost
{
  [ServiceContract()]
  interface IRestService
  {
    /// <summary>
    /// Return a json string
    /// </summary>
    /// <returns></returns>
    [OperationContract()]
    [WebGet(ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Bare) ]
    string GetJson();
  }
}

using System.IO;
using System.ServiceModel;
using System.ServiceModel.Activation;

namespace PERFoRM_LhnetRESTServiceHost
{
  [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Single, IncludeExceptionDetailInFaults = true)]
  [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
  class RestService : IRestService
  {
    /// <summary>
    /// Return a json string
    /// </summary>
    /// <returns></returns>
    public string GetJson()
    {
      string retJson = "{\"firstname\": \"Georg\", \"name\": \"Clooney\"}";

      // Only a test
      using (StreamWriter sw = new StreamWriter(new FileStream(@"D:\Temp\Json.txt", FileMode.OpenOrCreate)))
      {
        sw.Write(retJson);
        sw.Flush();
      }
      return retJson;
    }
  }
}

{"firstname": "Georg", "name": "Clooney"}

"{\"firstname\": \"Georg\", \"name\": \"Clooney\"}"

namespace WpfApplication1 {
    /// <summary>
    /// Interaction logic for SerialMonitor.xaml
    /// </summary>
    public partial class SerialMonitor : Window {
        
        //VARIABLES
        public SerialPort comPort = new SerialPort();

        public SerialMonitor() {
            //initialization
            InitializeComponent();
            scanPorts();
           
        }

        
        
        private void scanPorts() {
            textBoxIndata.Clear();
            string[] ports = SerialPort.GetPortNames();
            foreach (string port in ports) {
                comboBoxPorts.Items.Add(port);
            }
        }
              
      

        private void openComBtn_Click(object sender , RoutedEventArgs e) {

            comPort.Parity = Parity.None;
            comPort.DataBits = 8;
            comPort.ReadTimeout = 500;
            comPort.StopBits = StopBits.One;

            if (comboBoxPorts.SelectedItem != null && comboBoxPorts.SelectedItem != null) {

                comPort.PortName = comboBoxPorts.SelectedItem.ToString();
                comPort.BaudRate = Convert.ToInt32(comboBoxBaud.Text);

                try {
                    //Open port and add the event handler on datareceived
                    comPort.Open();                 
                    comPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
                }
                catch (Exception ex) {
                    MessageBox.Show(ex.ToString());                    
                }              
            }
            if (comPort.IsOpen) {
                label1.Content = "COM PORT OPEN";              
            }
        }


        private void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e) {
            
        }


        //function to update the textBox, didn't manage to get it working
        private void updateUI (string s) {

        }



        //CLOSE AND EXIT BUTTONS
        private void closeComBtn_Click(object sender , RoutedEventArgs e) {
            if (comPort.IsOpen) {
                comPort.Close();
                label1.Content = "COM PORT CLOSED";
            }
        }

        private void exitBtn_Click(object sender , RoutedEventArgs e) {
            if (comPort.IsOpen) {
                comPort.Close();
            }
            this.Close();
        }
    }
}