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February 11, 2021

According to Gartner, a legacy application can be defined as “An information system that may be based on outdated technologies but is critical to day-to-day operations”. The age of an application or its technology does not always determine whether it is a legacy one, rather its inability to meet the growing business demands of an enterprise classifies it as a legacy application. Studies by analyst groups have depicted that 90 percent of businesses run their operations on legacy applications. Enterprises also bear substantial expenses in maintaining them. Modernizing these legacy applications frees up enterprise resources to be invested on strategic initiatives for expanding market base and increasing revenue.

If enterprises decide to continue using robust legacy applications for uninterrupted business operations, they will need to overcome the following challenges:

  • Unavailability of Subject Matter Experts (SMEs) for the application/technology

  • Unavailability of existing functional/technical documents

  • Risk of application crashes when functionality enhancements are attempted

Transforming Applications – The Four Rs

The multibillion-dollar application modernization market is projected to witness a double-digit growth percentage in Compound Annual Growth Rate (CAGR) within the next five years. This clearly indicates that enterprises are planning a transformation of their legacy applications. Legacy application transformation methodologies can be classified as the following four Rs:

  • Re-platform

  • Refactor

  • Re-architect

  • Replace


Enterprises can re-platform applications by upgrading to a higher version of the technology. The evolving technology landscape provides ample opportunity for upgrading applications. It is of paramount importance to ensure that the necessary precautions are taken during the upgrade, so that deprecated functions or methods, changes to parameters and such are handled as per the requirements. For a large number of files, the possibility of errors is high if the upgrade is executed manually. When provided with the meta-data and source code of the application, automation ensures a hassle-free migration or technology upgrade, while catering to the preset conditions or rules of the product. The application transformed using Re-platform methodology faces comparatively higher maintenance costs than the other methodologies.


In order to enhance performance using new, innovative options available from recent technological advancements, enterprises seek opportunities to transition from their legacy technology stack. In case of application refactoring, codes of the legacy technology are translated to a more recent technology without affecting the existing functionality of the application. Before executing the application translation, understanding the existing application is a vital prerequisite. Deciphering legacy applications play a major role, since proper documentation and skilled SMEs may not be available in the enterprise. A product-based solution enables the understanding of the legacy application, using knowledge obtained from the legacy source code. In this methodology, application translation is carried out to arrive at the target technology.


Among the available options, Re-architect is the ideal methodology to transform an application. However, the cost and time required to implement this is much higher than the previously described methods. Since the complete application is re-architected, the latest technology and future-proof architecture can be designed and implemented for the application. Re-architecting the complete application involves analyzing its blueprint, including call graphs, program flows and flow charts. The business rules need to be extracted and statically analyzed. Knowledge from the existing source code then enables developers to build a new, modern application with redefined user interfaces, micro-services, and necessary APIfication that can be deployed on cloud.


While the methods described previously involve working on the existing code of the application, this methodology analyzes the code statistically. It is important to understand the application blueprint along with the business rules. On completion of rule rationalization and review, the required rules can be configured on the Commercial Off-the Shelf (COTS) product. After the application is replaced with the new COTS product, the maintenance cost turns out to be the lowest in this methodology, making it the most economically viable option.

Data Migration – An Imperative

All the transformation processes will remain incomplete, if the database is not transformed to a modern, compatible format aligned with the transformed application. Manual data transformation is next to impossible for large applications, hence relying on a suitable tool to implement automation enables enterprises to complete their transformation journey effectively.

Application transformation methodology depends on several factors. Hence, one size does not fit all. Just any transformation methodology cannot be implemented to achieve the target state. In order to avoid technological debt and stay recent, enterprises must make an informed decision and tailor their application transformation journey judiciously.

For any queries related to Application transformation, write to us

Navaneetha Krishnan is a Delivery Partner, currently working with TCS MasterCraft™ TransformPlus, which is an automated modernization and rapid application development platform helping enterprises in their digital journey without business disruption. He has over 13 years of industry experience including Java based Product Development/Design, Legacy Modernization, Application/DB Migration & Digital Transformation.


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