VB6 Hybrid Application Architecture

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Introduction

There are many applications written in VB6. Now rewriting an entire application to VB.NET is a time consuming and risky task for small companies. However, with the release of Microsoft Interop Toolkit 2.0, we have the option of partial migration. We can create Forms, Controls and Libraries in VB.NET and glue them with the VB6 application using the Microsoft Interop Toolkit 2.0. This option opens us to a lot of possibilities like calling a web service, threading and more. This article will demonstrate how advanced functionality can be added to a VB6 application using the Microsoft Interop Toolkit 2.0 and VB.NET without changing existing code. The list of features we will add is as follows:

• Writing VB.Net CRM Adapter for communication with Sugar CRM
  • Sugar CRM exposes its objects via the NuSoap PHP Library module
  • VB.NET Project will consume the web service
• Custom screen to create incidents in Sugar CRM
  • VB.NET Forms for creating incident
  • Incident creation screen will be called by VB6 application
• Multi-threaded bulk upload control
  • VB.NET UserControl that will upload incidents using System.ComponentModel.BackgroundWorker
  • VB6 Form will host this control.

Note: Sugar CRM is an open source CRM package based on PHP and MySQL.

High level design

In high level diagram Sections 1, 2 and 3 are VB6 Forms. Section 4 is a VB.NET WinForm. Section 5 is a VB6 Form hosting a VB.NET user control. Section 6 is the ToolKit area that provides sharing of application data, eventing framework services, etc. Section 7 is a CRM Adapter written in VB.NET to talk to the Sugar CRM SOAP Service. The application consists of the following projects:

1. Manager: Visual Basic 6.0 application starting point, contains forms
2. SugarCrmInteropForm: .NET assembly containing incident related forms
3. HybridAppControls: .NET assembly containing custom user controls for threaded bulk upload
4. SugarCrmAdapter: .NET assembly containing Adapter for Sugar CRM

Background

The application we are working with is Billing Management System. It's a Windows-based application with the Access database as its backend. Data reports are used for reporting. It is primarily used for managing customer contacts (CRUD), generating & maintaining billing information, reporting, etc.

Using the code

Sharing data between VB6 and VB.NET

Step 1. When Visual Basic 6.0 Application loads, initialize the Microsoft Interop Toolkit 2.0 Framework using following code:

' Instantiate the Toolbox
Set g_InteropToolbox = New InteropToolbox
g_InteropToolbox.Initialize
    
' Call Initialize method only when first creating the toolbox
' This aids in the debugging experience
g_InteropToolbox.Initialize

' Signal Application Startup
g_InteropToolbox.EventMessenger.RaiseApplicationStartedupEvent

Step 2. Using the Microsoft Interop Toolkit 2.0 Framework, pass all shared data to VB.NET:

'1.Reading Config values from Access Database
'2.Sharing the values to VB.Net using ToolKit  
Dim rsSettings As ADODB.Recordset 
Set rsSettings = New ADODB.Recordset 
rsSettings.Open "select * from appsetting", db, _
    adOpenDynamic, adLockOptimistic 
While Not rsSettings.EOF 
    g_InteropToolbox.Globals.Add CStr(rsSettings!Name), _
        CStr(rsSettings!Value) 
    rsSettings.MoveNext 
Wend 
rsSettings.Close

Step 3. Access shared data from VB.NET:

SugarCrmSettings.crmUserId = My.InteropToolbox.Globals("crmUserId")
SugarCrmSettings.crmURL = My.InteropToolbox.Globals("crmURL")
SugarCrmSettings.crmPassword = My.InteropToolbox.Globals("crmPassword")
SugarCrmSettings.crmVer = My.InteropToolbox.Globals("crmVersion")  

Multi-threaded bulk upload control in VB.NET

Step 1. Add the BackgroundWorker control from the Components ToolBox.

Step 2. In the DoWork event, we read the file and then call Adapter to create an incident:

Private Sub BulkImportWorker_DoWork(ByVal sender As System.Object, _
    ByVal e As System.ComponentModel.DoWorkEventArgs_
    ) Handles BulkImportWorker.DoWork
    Dim ReadFile As New System.IO.StreamReader(txtImportFileName.Text)
    Dim ImportedIncident As String
    Dim SugarCrmSettings As New SugarCrmAdapter.CrmHelper

    'Getting VB6 Configuration values
    SugarCrmSettings.crmUserId = _
        My.InteropToolbox.Globals("crmUserId").ToString()
    SugarCrmSettings.crmURL = _
        My.InteropToolbox.Globals("crmURL").ToString()
    SugarCrmSettings.crmPassword = _
        My.InteropToolbox.Globals("crmPassword").ToString()
    SugarCrmSettings.crmVer = _
        My.InteropToolbox.Globals("crmVersion").ToString()
    Dim lineno As Integer
    lineno = 1
    Dim importerror As Integer
    importerror = 0

    Try
        While Not ReadFile.EndOfStream
            ImportedIncident = ReadFile.ReadLine

            txtStatus.Text = "Processing Line  " + lineno.ToString()
            Dim IncidentRequest As New SugarCrmAdapter.Incident
            Dim IncidentResponse As New SugarCrmAdapter.GenericEntity

            IncidentResponse = 
                IncidentRequest.Create(SugarCrmSettings, _
                    ImportedIncident)
            If (IncidentResponse.IsError) Then
                ExportList.Items.Add("Line # " + lineno.ToString() + _
                    " Error occured while creating Case " + _
                    ImportedIncident)
                importerror = importerror + 1
            End If
            lineno = lineno + 1
        End While
        lineno = lineno - 1
    Catch ex As Exception
        Microsoft.VisualBasic.Interaction.MsgBox(_
            "Unexpected error " + _
            ex.Message, _
            MsgBoxStyle.Information)
    Finally
        ReadFile.Close()
        Dim summary As String
        summary = vbCrLf + "Total records processed: " + _
            lineno.ToString() + vbCrLf
        summary += "Successfully inserted: " + _
            CStr(lineno - importerror) + vbCrLf
        summary += "Failed: " + importerror.ToString() + vbCrLf

        Microsoft.VisualBasic.Interaction.MsgBox(_
           "Import task complted" + _
            vbCrLf + summary, MsgBoxStyle.Information)
        txtStatus.Text = "Completed..."

    End Try
End Sub

Writing VB.Net CRM Adapter for communication with Sugar CRM

Step 1. Call the test method of the Sugar CRM web service to check the connection.

Step 2. Pass the credentials to the create_case method.

Step 3. Return the response of the create_case method, which will be a GUID:

Dim crm As New CrmService.sugarsoap
Dim auth As New CrmService.user_auth
auth.user_name = ConnectionSettings.crmUserId
auth.password = ConnectionSettings.crmPassword
auth.version = ConnectionSettings.crmVer
crm.Url = ConnectionSettings.crmURL

Dim ReturnObject As New GenericEntity
Try
    Dim test As String = crm.test("test")
    Dim a As Object = crm.login(auth, "SoapTest")
Catch ex As Exception
    ReturnObject.IsError = True
    ReturnObject.Message = "Connection to SugarCrm was unsuccessfull"
    Return ReturnObject
End Try

Try
    Dim caseid As String = _
        crm.create_case(ConnectionSettings.crmUserId, _
        ConnectionSettings.crmPassword, CaseName)

    ReturnObject.Message = _
        "Case created in SugarCrm with CaseID - " + caseid
    Return ReturnObject
Catch ex As Exception
    ReturnObject.IsError = True
    ReturnObject.Message = _
        "Unable to create case in SugarCrm ErrorDetails - " + _
        ex.Message
    Return ReturnObject
End Try

Tips for success

Before running the application, check the following:

1. Check that Sugar CRM is running.
2. Check that the settings like CrmURL point to the correct location.
3. Note that the password stored in MD5 can be taken from the Sugar CRM user table.
4. The user should have rights for creating incidents in Sugar CRM.

Happy coding...

History

• 4 July, 2007 -- Original version posted