title: How to build a web service rest in visual basic?
body: <p>I'm building a simple web service with visual basic. This web services should to get in input a JSON and return a value.
  The method of this web service is POST.</p>
  
  <p>This is the code:</p>
  
  <pre><code>    &lt;WebMethod()&gt;
          Public Function MB_InsertBeetrader(ByVal inputData As AMAServerInputData) As AMAServerOutputData
              Dim returnData As New AMAServerOutputData()
  
              Try
  
  
              Catch ex As Exception
                  returnData.Messages.AddExceptionMessage(ex)
              End Try
  
              Return returnData
          End Function
      End Class
  
  Public Class AMAServerInputData
      Inherits Base_ServerInputData
      Public Username As String
      Public Password As String
  End Class
  </code></pre>
  
  <p>If I try to call this method from my PostMan client I have an error.
  This is my call:</p>
  
  <pre><code>{ "Username": 656, 
  "Password": "128"
  }
  </code></pre>
  
  <p>This is the error:</p>
  
  <blockquote>
    <p>{
      "Message": "Chiamata a servizio Web non valida. Valore mancante per il parametro 'inputData'.",
      "StackTrace": "   in System.Web.Script.Services.WebServiceMethodData.CallMethod(Object target, IDictionary<code>2 parameters)\r\n   in System.Web.Script.Services.WebServiceMethodData.CallMethodFromRawParams(Object target, IDictionary</code>2 parameters)\r\n   in System.Web.Script.Services.RestHandler.InvokeMethod(HttpContext context, WebServiceMethodData methodData, IDictionary`2 rawParams)\r\n   in System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)",
      "</p>
  </blockquote>