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					           Visual Basic 6.0 to .NET Migration
           - Azhar Amir

           The move from Visual Basic 6.0 (VB6) to Visual Basic.Net
           (VB.NET) is primarily driven by the fact that Mainstream
           support for VB6 has ended. Companies which want to stay
           ahead can utilize the benefits of latest .Net technology to
           give new life to their mission critical applications. Hence in
           this paper we will be looking at migration of these
           applications from VB 6.0 to .Net.
           This paper focuses on the methodology and techniques
           which Infosys (Microsoft Technology Center) has
           developed for migrating VB6.0 Applications to .NET. Our
           approach ensures a smooth, cost effective, and efficient
           migration of VB 6.0 Applications to .NET. We leverage the
           features available on the .NET platform to implement a
           loosely coupled Service Oriented Architecture. We have
           also devised the methodology that automates the analysis
           and conversion process. We have successfully
           demonstrated the ROI using our Catalytic IT offerings.

Feb 2008
Visual Basic 6.0 Application Migration Solution
Migration of a VB 6.0 application is not just a one–to-one code conversion, which is the common
understanding, In other words, Application Migration is more than just a code conversion it also
involves analysis, assessment and followed up by code migration and testing. The reason being-
the application migration is driven not only by technology drivers, but also by business drivers.
Thus technology combined with business drivers will provide various the right direction for
migration of the existing Visual Basic 6.0 application to the target .Net platform. Some of the
common business drivers that lead to migration of Visual Basic application are
    •   Need to integrate with other systems in the enterprise
    •   Less turnaround time for frequent functional changes
    •   Scaling up the existing system to large number of users
    •   Extend functionality to other delivery channels

Typically, legacy applications do not have proper documentation (requirements, design
documents, user manuals and comments in code), in place. Nevertheless, assessing and
analyzing the existing application (and other applications that require migration) is a must, so as
to understand the requirements (functional and non-functional), and to formulate a migration path
& strategy for the entire application base.

Based on the technical and business drivers, there are multiple approaches which Infosys
suggests to migrate Visual Basic applications to .Net like
    •   Quick and automated migration to .Net
    •   Re- Architecting - Hybrid
    •   Service orientation - Manual

A hybrid approach is a combination of the tool-based and manual conversion approaches. It is,
generally, most suitable to typical legacy application migration projects involving changes in

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Migration Methodology

Figure 1: Infosys Migration Methodology

Infosys has been working towards providing a smooth transition of applications from VB6 to .NET
and has devised the above given methodology for doing the same.

Infosys has a 4 phased approach for migration of VB applications to .Net. The phases are as

             Assessment                         Definition
             Migration                          Deployment

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Infosys has identified high level activities that need to be performed at each of the mentioned
phases. To enable better productivity, each of these phases will utilize tools made by Microsoft
and also few custom tools built by Infosys.

The methodology defined by Infosys can be utilized at any of the various approaches that are
mentioned above.

Infosys has proven the suitability of this approach and its tools by migrating complex Visual Basic
6.0 Client applications on to the .NET platform within a reduced time frame, as compared to a
manual conversion, which actually translates as ROI for the client.

The automation of the VB6.0 to .Net is done by using Infosys custom tool known as Visual Basic
Migration Accelerator for Enterprise Migration Workbench. This takes care of automating various
activities at each phase of the migration.

i.   Assessment phase

During this phase, Application Inventory Gathering, Application Portfolio Analysis and estimations
are done to come out with a migration roadmap for the entire VB Application portfolio of the client.

In cases where there is only one application, visual basic migration workbench can be used
directly without any portfolio analysis to assess the application.

Figure 2 : Assessment Phase

Simultaneously, with the estimations, migration solutions are analyzed and a mapping is made
with regards to the best solution strategy that fits to each application, individually. This helps to
quickly identify rationalization opportunities and recommend strategies to optimize the application

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ii. Definition Phase

The phase II which is the definition phase is the phase where inputs from the phase I are used to
arrive at the desired future state of architecture.

During this phase, if there are any new functional requirements needed for the future state
application, those requirements are defined.

Figure 3 : Definition Phase

Also if there are proofs that need to be established for any complicated functional
implementations, a Proof of concept will be undertaken.

iii. Migration phase

This is the phase when the actual code migration will be done. Inputs from both the assessment
and definition phase are taken into this phase.

The pre migration steps are performed based on the approach for migration defined during the
definition phase.

Figure 4 : Migration Phase

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The source code will be prepared for migration which is primarily the pre migration step. The
source is then migrated using the Infosys Enterprise migration workbench detailed below.

The source code is then ready for post migration changes which are to fix the issues that are
pending after the migration. This part of the effort is manual.

Infosys has developed Enterprise Migration workbench, to migrate applications to newer
technologies to benefit from new features, without losing the investment in existing legacy code
base. Enterprise Migration Workbench platform has several accelerators which take care of
migrating VB to Vb.Net, SQL Server 2000 to 2005/2008, BizTalk Server 2004 to 2006,
SharePoint Portal Server 2003 to MOSS 2007. These accelerators leverage Microsoft upgrade
wizards wherever possible and bridges the technical gap not achievable through Microsoft

Each of these accelerator works in 3 phased approaches as explained below

  Configure       In this phase the tool is configured to retrieve source code from
                  application/database server

  Discover        Tool is run to identify any missing source code files, source code completion
                  check, complete code analysis and provides comprehensive report to highlight
                  complexity of migration, source code dependency, missing files, code flow
                  path, deprecated methods, and unsupported components.

  Migrate         In this phase the tool migrate the source code to newer version by replacing
                  deprecated APIs with new equivalent APIs. Sometimes depending on the
                  usage of 3rd party and other components, source code may not be migrated
                  completely and in such cases it has to be done manually post migration phase.
                  Infosys has built mappings for several third party VB components to migrate it
                  to corresponding .Net components

There are other value adds to the tool
        a. Migration from VSS to VSTS
        b. Migration of SQL to 2005 and Performance Analysis

For customers looking at service enabling, we recommend a phased roadmap to SOA, the code
can be service enabled post migration to pure .Net by making changes in underlying code or
building wrappers around existing methods.

The tool based approach has following advantages and several clients have liked this over a
    •   Upfront Identification of code complexity, and magnitude of deprecated/unsupported
        APIs, methods
    •   Automation of manual code change, replacing deprecated methods
    •   Automated migration of ActiveX components to corresponding .Net components
    •   The tool can be run on code in offline mode

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While the tool enables 30% or more automation, it also depends upon the underlying source
code. Importantly post migration the code doesn’t depend on tool and new technology can be
leveraged to fullest.

The tool based migration is recommended where the underlying source code is fairly structured in
to multiple layers like presentation, business, and data and can be taken in a new environment. If
the source code is spaghetti the tool usually, cannot do much to separate into multi layers. The
tool can be run independently on different layers like Presentation, business or data layers and
can be used to migrate only specific layer as required.

iv. Deployment phase

The entire migrated application is tested for errors/bugs using test cases created in the Analysis
& Design steps. The number of classes, methods, framework components and other features that
are converted are also identified to resolve logical errors, performance bottlenecks and functional

Based on the deployment environment and the other parameters considered, the migrated
application is deployed at client location. It is run in parallel with the existing visual basic
application to
    –   Check the if functional equivalence is established
    –   To avoid bringing down the system during replacement.

It also involves post deployment consultation/support activities (onsite/offshore depending on
criticality of the client’s request).

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It is known that Visual Basic is being phased out by Microsoft and also companies want to meet
the upcoming challenges in business requirements. This changing business scenario is leading to
the advent of newer technologies like .Net occupying the scene.

Infosys is thus filling the need for these companies to migrate from Visual Basic to .Net
Technologies’. The advantages of using .NET provide all the reasons to use it as target
technology for these applications. Moreover, it’s a new technology and would most assuredly
keep the doors open for future changes and enhancements.

Using Infosys methodology, and a set of effective tools like Visual Basic Migration Work Bench
and Infosys’ Techniques; Infosys has successfully demonstrated the credibility of the above given
approaches for VB 6.0 to .NET Migration. It has also solved all problems arising during the entire
migration process.

The above steps supported and suggested by Infosys have been proven and quantified.

The methodology guarantees to save:
    •   Approximately 50-60% of efforts while understanding the application architecture,
    •   Approximately 65- 70% of efforts while understanding and documenting round trip
    •   Approximately 25- 40% (average) of coding effort using Infosys automation tools.

Infosys would also leverage its successful onsite-offshore model to provide customers with high
quality migration services. With its deep .NET technology expertise, Infosys ensure smooth
migration to the .NET platform.

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      About the Author
      Azhar Amir has more than 10 years of experience in IT industry. He is an Architect with
      Infosys Technologies and is part of the Microsoft Technology Center. He has deep
      knowledge on providing solutions for modernizing legacy application to newer
      technologies like .Net and also in defining enterprise architecture. Azhar has also been
      a part of a few white papers and book publications.

      The author would like to sincerely thank Mr. Srinivasan Natrajan Prinicipal Architect Infosys
      Technolgies Limited, Autl Gupta Prinicipal Architect Infosys Technolgies Limited, Srividya
      Saptharishi Architect Infosys Technologies and Sudhanshu Hate Architect, Infosys
      Technologies Limited.

© 2008 Infosys Technologies Limited.


Copyright in whole and in part of this document “Visual Basic 6.0 to .NET Migration” belongs to Infosys Technologies Limited. This work
may not be used, sold, transferred, adapted, abridged, copied or reproduced in whole or in part in any manner or form or in any media
without the prior written consent of Infosys Technologies Limited.

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