Introduction and Background

In a rapidly evolving digital landscape, legacy code migration is becoming crucial. It is the transformative process of upgrading outdated software systems to modern, efficient, and sustainable codebases. It involves rewriting, refactoring, or re-architecting legacy applications to meet current technological and business needs. Legacy code migration is crucial for organizations to enhance performance, reduce maintenance costs, and improve security. This requires careful planning and precise execution, and leverages advanced technologies like generative AI to streamline the transition whereas minimizing risks and disruptions.

Objective

This article aims to provide a comprehensive understanding of how generative AI can be leveraged to streamline the migration of legacy code to modernized, future-proof codebases. We will explore the benefits, challenges, and best practices associated with this approach.

The Legacy Code Challenge

Legacy code refers to software systems or components that were developed using outdated technologies or practices. These systems are often difficult to maintain, lack compatibility with modern platforms, and may be prone to security vulnerabilities.

Challenges in Maintaining Legacy Code

The challenges posed by legacy code include:

• Lack of Documentation: Legacy code often lacks proper documentation, making it difficult to understand its functionality and architecture.
• Outdated Technologies: Legacy code may be built on outdated technologies and dependencies that are no longer supported or efficient.
• Complex and Monolithic: Legacy codebases tend to be monolithic and tightly coupled, making it challenging to make changes without causing unintended side effects.
• Inefficient Code: Legacy code may contain inefficiencies and performance bottlenecks.
• Security Vulnerabilities: Older code often lacks modern security practices, potentially exposing it to vulnerabilities.
• Dependency Hell: Managing dependencies can be difficult in legacy code, with outdated libraries and conflicts.
• Knowledge Gaps: Over time, knowledge about the codebase may have been lost owing to staff turnover or neglect.
• High Maintenance Costs: Legacy systems require substantial resources for maintenance and bug fixes.

Code Modernization

Code modernization is the process of updating and improving existing software code to make it more efficient, maintainable, secure, and aligned with current best practices and technologies. There are several compelling reasons for code modernization:

• Improved Maintainability: Over time, software code can become convoluted and difficult to understand. Code modernization involves refactoring and restructuring code to make it more organized and readable.
• Enhanced Performance: Modernizing the code leads to performance improvements, making the software more responsive and efficient.
• Security Enhancement: Code modernization includes security audits and updates to ensure that the software is protected against common threats and follows secure coding practices.
• Compatibility: Modernizing the code ensures that it remains compatible with the latest software and hardware environments.
• Scalability

Functionality of Infosys Migration Workbench

Infosys Migration Workbench is a platform designed to facilitate the process of transforming legacy code into modern code. It provides a set of features that aids in the migration and modernization of software systems. Key functionalities typically include code analysis, entity extraction, business rules generation, and microservice architecture-based code generation.

Fig [1]: Overview of Infosys Smart Modernization Workbench

Code Analysis

Code analysis helps in understanding the existing codebase, identifying potential issues, and to plan an effective strategy for modernization. Existing documentation related to the legacy code, such as design documents, architecture diagrams, and user manuals is gathered. Inventory of all code and related assets, including source code files, libraries, databases, and configuration files are created. A comprehensive manual code review to understand the structure, logic, and functionality of the code is being done. Dependencies including external libraries, APIs, and third-party services that the code relies on are documented. An extensive report that summarizes the state of the legacy code, highlighting key issues and a roadmap to address the issue and modernize the code will be the step further.

Entity Extraction

Once the legacy code is analyzed, it is uploaded to the Migration Workbench to extract the entities. Entity extraction is valuable as it assists in understanding and transforming legacy code more effectively. It aids in mapping legacy entities to their modern equivalents. Entities reveal the relationships and dependencies between various code entities which is crucial for restructuring or refactoring code components. Entities extracted are being stored for further processing and migration.

Fig [2]: Entities Extracted after Uploading of Legacy Code

Business Rules Extraction

Extracting business rules from legacy code is a critical and foundational step in the code modernization process. By doing so, developers can gain a clear understanding of how the system works, its intended behavior, and its rules. Understanding the existing business rules allows us to adapt and translate these rules to fit into new technologies, platforms, or architectural paradigms as part of the modernization effort. Validating the modernized code against the extracted business rules helps ensure that the system meets user expectations and requirements.

Fig [3]: Business Rules Generated from the Legacy Code

Select the Target Framework

Selecting the target framework is a complex decision that requires a thorough analysis of both technical and strategic factors, which is aligned with the project’s goals. Platform compatibility, database support, and integration capabilities are various factors that are being taken into consideration. The selected framework must have long-term support, updates, and maintenance to guarantee the continued health of the modernized code. After the target framework is selected uploaded legacy code’s migration process starts.

Fig [4]: Selecting the Target Framework

Migration Process

Migrating to a micro front-end architecture from a legacy codebase is a complex and iterative process. This involves using a client-side framework that is chosen to render the micro front ends. Business rules and the entities generated play a vital role in the generation of migrated screens. Hence it is important that they are being reviewed and modified as necessary.  Migrating the middle tier is critical as well, as it involves business logic and is responsible for handling user requests and managing data interactions. The data layer involves moving and transforming data, and updating databases and data structures thereby ensuring data consistency, integrity, and accessibility in the modernized system. Fig [5] mentions the different jobs that do the work of migration from extracting the files in the source system to connecting with the generative AI APIs and doing the work of migration.

• Split file job helps make the code more maintainable, improve readability, and facilitate modernization efforts by making the code smaller and more modular.
• Migrate file job helps in the transformation of legacy to modernized code by connecting to the required APIs.
• LLM Response Handler job responsible for processing and managing responses from various sources, such as web services, and APIs.
• LLM Connector jobs involve connecting or integrating the legacy code with modernized technologies and systems.

Fig [5]: Migration Jobs

Once the code is migrated, the user is given the option to review, edit, and save every migrated file as needed. Also, the user is given the option to toggle between the changes made and the original migrated version. Fig [6] mentions the same about the legacy and the migrated code in the side-by-side view. Commenting on the edited version helps the team members on what the change made to the original migrated version. The same can be sent for approval and saved.

Fig [6]: Legacy and the Migrated Code

Challenges and Considerations

Migrating legacy code to modernized code using a migration workbench is a complex undertaking that requires careful planning, thorough testing, and attention to detail. The below points are to be taken into consideration with migration:

• Clear Objectives: Define clear objectives for the migration, such as improving performance, enhancing security, or complying with industry standards.
• Selecting the Right Approach: Choose the most suitable migration approach, whether it’s a complete rewrite, partial migration, or a lift-and-shift strategy.
• Testing Strategy: Establish a comprehensive testing strategy that includes unit testing, integration testing, and user acceptance testing. Test early and often.
• Documentation: Document the modernized code thoroughly, including comments and documentation to aid future maintenance.
• Backup and Rollback Plan: Create a backup and rollback plan to minimize downtime and data loss in case of migration issues.
• Post-Migration Monitoring: Implement post-migration monitoring to identify and address any issues that may arise after the migration.

Real Case Examples during PoC

Example 1: Legacy COBOL System to Microservices

Initial State

• A big financial institution was running its core banking system on a legacy COBOL system that was becoming increasingly expensive and challenging to maintain.
• The legacy system was monolithic, difficult to scale, and didn’t integrate well with modern financial technologies.
• The institution was experiencing high operating costs, extended development cycles, and limited adaptability.

Migration Process

• The institution decided to migrate its core banking system to a modern microservices architecture using the Infosys migration workbench designed for such transitions.
• Infosys migration workbench identified modularization opportunities, extracted entities, and business rules, and generated new microservices.
• The team analyzed the codebase, decoupling tightly coupled modules.
• Continuous integration and deployment practices were implemented.

Outcomes

• The migration significantly reduced operating costs, improved system scalability, and decreased time-to-market for new features.
• The institution’s core banking system became more adaptable, allowing for quicker integration with modern financial technologies.
• Microservices architecture improved code maintainability, enabling multiple development teams to work concurrently.
• Overall, the migration led to greater operational efficiency and enhanced customer experiences.

Example 2: Legacy Web Application Modernization

Initial State

• A retail company had a legacy e-commerce web application that was slow, outdated, and prone to security vulnerabilities.
• The company was losing customers to more modern and responsive competitors.
• The legacy codebase was challenging to maintain and enhance.

Migration Process

• The retail company utilized an Infosys migration workbench that focused on web application modernization.
• Legacy code analysis was done to identify performance bottlenecks and security issues.
• The company decided to redevelop the front end using a modern framework whereas keeping the backend services intact.
• User data was securely migrated to a more robust database system.
• Comprehensive testing was conducted to ensure the modernized application worked as intended.

Outcomes

• The modernized web application resulted in faster page load times and a more responsive user interface.
• The company saw an increase in online sales and customer engagement.
• Security vulnerabilities were addressed, and the application was better protected against cyber threats.

Conclusion

In conclusion, migrating from legacy to modernized code is of paramount importance for organizations seeking to remain competitive, efficient, and secure in today’s fast-paced technology landscape. It offers the opportunity to address the limitations and challenges posed by outdated systems and to leverage modern technologies, development practices, and architectural patterns. Migration, when executed effectively with Infosys migration workbench, can lead to improved efficiency, better user experiences, and reduced operational costs, ultimately contributing to an organization’s long-term success and growth.