how validate VAT with WSDL SOAP Service with VB2019 ?

Question

i like add few lines in my program that validate VAT in Europe.

I use Visual Studio Community 2019, Windows form, Net Framework 4.5.2,

A// I created new Solution/Project with form1

B// i defined design

textbox1 - country / for example "SK"

textbox2 - numberpart of VAT /for example 2020332105/

Textbox3 - for output from webservice

Button1 - for handle to validate VAT

C// i added service reference. Right click on project - ADD - Service Reference

i put link wsdl for reference

[http://ec.europa.eu/taxation_customs/vies/checkVatTestService.wsdl]

i clicked OK and i have now in project added Connected Services -ServiceReferences1

D// and now i want to write some code for sending request and to get validation code but i didnt find any good help on web for VB. On the net is many articles in C, python but nothing useful a really simple for Visual Basic. Can you help to write code for sending CheckVat metode to this webservice ?

thx

Answer 1

Hi @is sro ,

Please check if the following code works for you.

        Dim client As New checkVatPortTypeClient()

        Dim countryCode As String = TextBox1.Text.Trim()
        Dim vatNumber As String = TextBox2.Text.Trim()
        Dim valid As Boolean
        Dim name As String
        Dim address As String

        Dim requestDate = client.checkVat(countryCode, vatNumber, valid, name, address)

        If valid Then
            Console.WriteLine("VAT number is valid.")
            Console.WriteLine("name: " + name + "; address: " + address + ".")
        Else
            Console.WriteLine("VAT number is invalid.")
        End If

        client.Close()

Best Regards.

Jiachen Li

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Answer 2

Dear Jiachen,

thx for your answer but i dont know what class i have to replace..

I got namespace ServiceReference1 and in object browser i see:

project: wsdl_vat

namespace: wsdl_vat.ServiceReference1

Classes:

Public Class checkVatApproxRequest

Public Class checkVatApproxResponse

Public Interface checkVatPortType

Public Class checkVatRequest

Public Class checkVatResponse

I changed class e.g. : ServiceReference1.checkVatApproxRequest()

but i got warning - ValidateVATNumber is not member of class...

and i didnt find class with this member ..

IS

Answer 3

Dear Jiachen,

thx for your help. I changed a little code because my VB had too many red lines , i had to define DIM with ServiceReference1, now i dont have red lines, but it still is calling exception when i run the program.

i believe you know what to change

Lubomir

more info;

It stops at line 6 : request.Body.countryCode = TextBox1.Text.Trim()

Write Exception:

System.NullReferenceException: 'Object reference not set to an instance of an object.' /line

Complet code /VB2019 /

Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim client As New ServiceReference1.checkVatPortTypeClient()
        Dim request As New ServiceReference1.checkVatRequest()
        Dim response As New ServiceReference1.checkVatResponse()
        request.Body.countryCode = TextBox1.Text.Trim()
        request.Body.vatNumber = TextBox2.Text.Trim()
        request.Body.countryCode = "SK"
        response = client.ServiceReference1_checkVatPortType_checkVat(request)
        If response.Body.valid Then

            TextBox3.Text = "VAT number is valid"
        Else
            TextBox3.Text = "VAT number is valid"
        End If
        client.Close()
    End Sub
End Class

Answer 4

Hi Jiachen, thx that you try to help me. i rechecked your modified code

it looks fine, but when i debug it, it stops at this line:

Dim requestDate = client.checkVat(countryCode, vatNumber, valid, name, address)

and writes this exeption:

Exeption unhandled

System.ServiceModel.Security.SecurityNegotiationException: 'Could not establish secure channel for SSL/TLS with authority 'ec.europa.eu'.'

Inner Exeption

WebException: The request was aborted: Could not create SSL/TLS secure channel.

Here i copy details from this exception

System.ServiceModel.Security.SecurityNegotiationException
  HResult=0x80131501
  Message=Could not establish secure channel for SSL/TLS with authority 'ec.europa.eu'.
  Source=mscorlib
  StackTrace:
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
   at wsdl_vat.ServiceReference1.checkVatPortType.checkVat(checkVatRequest request)
   at wsdl_vat.ServiceReference1.checkVatPortTypeClient.ServiceReference1_checkVatPortType_checkVat(checkVatRequest request) in D:\adata\programovanie\wsdl_vat\Connected Services\ServiceReference1\Reference.vb:line 358
   at wsdl_vat.ServiceReference1.checkVatPortTypeClient.checkVat(String& countryCode, String& vatNumber, Boolean& valid, String& name, String& address) in D:\adata\programovanie\wsdl_vat\Connected Services\ServiceReference1\Reference.vb:line 366
   at wsdl_vat.Form1.Button2_Click(Object sender, EventArgs e) in D:\adata\programovanie\wsdl_vat\Form1.vb:line 35
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
   at wsdl_vat.My.MyApplication.Main(String[] Args) in :line 83

  This exception was originally thrown at this call stack:
    [External Code]

Inner Exception 1:
WebException: The request was aborted: Could not create SSL/TLS secure channel.

i hope you can figure out problem...

is

Answer 5

Dear Jiachen,

Thank you, i solved the problem with code, and your code really helped. Finally problem was with wsdl.

Once again thx

is