Legacy software modernization: your guide to a successful project start

Initially, the software is developed to solve specific business problems according to existing requirements based on selected technologies.

The typical reasons for modernization are lack of maintenance, changing business requirements and inability to implement required tasks within the legacy framework/technology.

Legacy software definition

Legacy application as an information system that may be based on outdated technologies but is critical to day-to-day operations. It may refer to applications, platforms, tools and programming languages that required to be replaced by modern technologies.

Very often the need to modernize a legacy system occurs due to the certain limitations or lack of functions that the software should perform. It may also include low performance, incompatibility with other systems, or an outdated user interface.

Preparing for the modernization project

Legacy software modernization is a frequently challenged and long-time project. However, it should pursue the main goal — cover current and future (short-term, related to plans) organizational needs.

Before undertaking any development paths it is better to start with creating the roadmap to define objectives for the modernization project.

A clear understanding of the current application status, its technical constraints and what tasks it should cover determines most of the overall project success.

The application assessment usually includes analysis of the structure, system functionality, performance, stability, redundancy, user interface, databases and system outputs.

There is also another factor related to people and organizations, that the project impact on many areas. New applications, data structures, data defragmentation and preparation, integrations, choosing the technology can be as long, as risky when there is no leadership on board.

Look at the project from the holistic point of view:

• What approaches to the modernization process might be chosen and which you consider as the best one?
• What are the main goals in the legacy modernization project and what you want to achieve — how you can measure the success?
• What costs and time are needed (and available) to achieve the modernization goals?
• What are the current software architecture and ecosystem (how many systems do you have, how they are connected, which of them you replace, where are the data sources)?

Estimating the budget and timeline for the software modernization project

The budget preparation and the timeline have to both flexible and realistic. Expectations to make the change quickly can ruin the whole preparation and effort of people making the modernization.

The typical considerations when making the transformation are related to the product fit (how the solution fit to the needs), the overall cost of ownership (not only the cost of license or development but overall cost by the years), technology currency and the implementation time.

Approaches to legacy software modernization

Re-building

This approach implies rewriting the application or system component (or as a whole) from scratch while preserving its scope and specifications without changing the system functionality.

Re-engineering

It includes restructuring and optimization of existing code without adding new components in order to simplify the system and remove unnecessary elements from it.

Re-platforming

Application or component migration to a new platform. In this case, there is no need in rebuilding application but just in tailoring it to the new targeted environment (typically cloud-based).

Re-architecting

It means significant changes in the application code so it can be shifted to the completely new and modern architecture (e.g. popular microservices). This approach is similar to rebuilding the application from scratch but with an assumption that the architecture also is changed.

Re-placement

This approach is used if there is no reason to invest in application or component modernization. As the result, it replaced by a new one that meets new requirements. It is worth mentioning that all these strategies are not mutually exclusive, and different strategies can be applied to specific parts or elements of the system.