Introduction

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On the Road to .NET

BMW Financial Services is committed to Microsoft technologies and has used Visual Basic (VB) as the mainstay of application development for over ten years. Our applications began taking shape in 1994, even as VB itself was still growing up. In early 2000, I was hired to manage the newly established system architecture team. We found ourselves facing a wide variety of architectures and coding styles. Although we are almost purely a VB shop, we had several different application frameworks and our code employed a number of different "standards" for common tasks. We also used over one hundred different third-party COM components. Our intent was to standardize our architectures and to implement more intelligent code reuse, but such changes are expensive and building a case purely on the basis of architecture goodness is near impossible.

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We planned three application frameworks to help us migrate: one for desktop, one for web, and one for batch jobs. We fondly refer to these frameworks as DesktopCAFE, WebCAFE, (CAFÉ stands for Common Application Framework for the Enterprise), and BEEF (Batch Environment Execution Framework). Each of these frameworks leverages .NET and the Microsoft Application Blocks / Enterprise library to provide architecture support for quickly assembling robust, modular applications.

By the end of 2003, we had published the Batch Architecture Strategy, the WebCAFE adoption strategy and had also deployed a very basic version of DesktopCAFE. Also in 2003, our service-oriented middle tier grew at frightening pace. In our haste to provide an easy-to-use service framework for the CRM project, we put very little governance around the creation of new services. This was both good and bad. On the good side: the C# middle tier provided a ready alternative to writing more VB. On the not so good side, it was the only alternative; and we soon had a library of over 100 services of questionable purpose.

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These five processes interact to reduce the cost and increase quality and speed of the .NET adoption effort. For example, an investment in Translation capability will result in higher quality C# code that is more correct and ready for Rearchitecting. An investment in Retooling will result in more repeatable translations, builds, and deployments, as well as smoother adoption of new architectures and tools. Rearchitecting will yield more complete specifications for Translation and a solid target for migrated applications. Testing will ensure that other migration processes are working properly. Managing coordinates and balances these activities to make the most efficient use of program resources. Figure 1 shows how these processes relate to each other.

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Figure 1: Relationships among the Five Pillars of Migration

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• The replacement of VB On Error Goto with Structured try-catch exception handling,
• The replacement of a legacy ADO wrapper function (ExecProc) with a call to our standard ADO.NET data access component (DataMeister). Note that DataMeister is a slightly modified version of the SQLHelper application block.
• The translation requires stored proc parameters information to setup the SqlParameter array. The translation tool is able to determine the names of proc parameters dynamically at translation time – a huge time saver.

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Public Function GetLessee(Acct As String) As String
    'Returns name of accountholder, if no last name then use company name.
    If gbErrorTrapOn Then On Error GoTo ErrorTrap
    Dim rs As ADODB.Recordset
    If ExecProc("cash", "cash_GetLessee", rs, -1, Acct, gsCountry) Then
        If Not rs.EOF Then
            If Len(Trim(rs!last_nme)) > 0 Then
                GetLessee = IIf(IsNull(rs!first_nme), "", Trim(rs!first_nme)) & " " & _
                IIf(IsNull(rs!last_nme), "", Trim(rs!last_nme))
            Else
                GetLessee = IIf(IsNull(rs!company_nme), "", Trim(rs!company_nme))
            End If
        End If
    Else
        GetLessee = "Unavailable"
    End If
    Exit Function
ErrorTrap:
        ShowError("GetLessee", Err.Number, Err.Description)
End Function

public static string GetLessee(string Acct)
{
    string GetLessee = "";
    // Returns name of accountholder, if no last name then use company name.
    SqlParameter[] sqlParms = new SqlParameter[2];
    try
    {
        SqlDataReader rs = null;
        sqlParms[0] = DesktopDataMeister.SetProcParameter("@account_no",
        ParameterDirection.Input, false, Acct.ToString(), 10);
        sqlParms[1] = DesktopDataMeister.SetProcParameter("@country_cde",
        ParameterDirection.Input, false, Cash_Globals.gsCountry.ToString(), 3);
        rs = DesktopDataMeister.ExecuteReader(DesktopConfigurator.EDBServer,
        CommandType.StoredProcedure, "Cash.dbo.cash_GetLessee", sqlParms);
        if (rs.Read())
        {
            if ((rs["last_nme"].ToString().Trim()).Length > 0)
            {
                GetLessee = (VBNET.Information.IsDBNull(rs["first_nme"]) ? "" :
                rs["first_nme"].ToString().Trim()) + " "
                + (VBNET.Information.IsDBNull(rs["last_nme"]) ? "" :
                rs["last_nme"].ToString().Trim());
            }
            else
            {
                GetLessee = (VBNET.Information.IsDBNull(rs["company_nme"]) ? "" :
                rs["company_nme"].ToString().Trim());
            }
        }
        else
        {
            GetLessee = "Unavailable";
        }
        return GetLessee;
    }
    catch (Exception exc)
    {
        ShowError("GetLessee", ABCFSException.MapExceptionToErrNumber(exc),
        exc.Message);
    }
}

Listing 1. Sample Translation produced by the Promula VB-to-C# Translation System

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Mark Juras is president of Great Migrations LLC, a technology solutions provider that specializes in helping people migrate their software applications from one platform to another via translation from one programming language to another. At the time of writing this article, Mark was System Architecture Manager for BMW Financial Services of North America.