Android Question how to retrieve dataset returned from web application

public class BarcodeController : ApiController

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace VV_Web_API
{
    public class Barcode
    {
        public string barcode = "123";
        public string marking = "marking";
        public string error = "";

    }
}

        //   http://localhost:52407/api/barcode/1?barcode=0108000000008&customer=0
        public Barcode GetById(int id, string barcode = "",string customer="")
        {

            Barcode bc = new Barcode();
         //...
            return bc;
        }

#Region  Activity Attributes
    #FullScreen: False
    #IncludeTitle: True
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.

End Sub

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.

    Private LabelBC As Label
    Private LabelError As Label
    Private LabelMarking As Label
End Sub

Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:
    Activity.LoadLayout("Marking")
  
    Dim BC As String
    BC = Main.ScannedBarcode
  
    Dim Job As HttpJob
    Job.Initialize("Job1",Me)
    Job.Username="..."
    Job.Password="..."
    Job.Download("https://xy.xy.com/api/barcode/1?barcode=" & BC & "&customer=kro")

End Sub

Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub JobDone (Job As HttpJob)
  
    Log("JobName = " & Job.JobName & ", Success = " & Job.Success)
    If Job.Success = True Then
        Select Job.JobName
            Case "Job1"

                Dim JSON As JSONParser
                JSON.Initialize(Job.GetString)

                Dim Map1 As Map
                Map1 = JSON.NextObject
              
                LabelBC.Text = Map1.Get("barcode")
                LabelMarking.Text = Map1.Get("marking")
                LabelError.Text = Map1.Get("error")
              
                'print the result to the logs
                Log(Job.GetString)
        End Select
    Else
        Log("Error: " & Job.ErrorMessage)
        ToastMessageShow("Error: " & Job.ErrorMessage, True)
    End If
    Job.Release
  
End Sub