Modernizing Legacy Systems: When Reengineering is really worthwhile

They are often the invisible backbone of a company: Legacy systems. Over the years or even decades, they reliably perform their service, but their [maintenance](/services/software maintenance and care) is becoming increasingly tolerated. The documentation is complete, the technology is outdated and experts are hardly to be found. At some point, the question inevitably arises: further flick or radically modernize? A reengineering, i.e. a fundamental revision of the old system, is a huge step. In this post, you will find out what signs you recognize the point of no return and when a reengineering is really worthwhile.

What is a legacy system?

A legacy system (old system) is a software that is still in operation, but is based on outdated technology and can only be maintained and developed with great effort. Typical features are:

Old technology: The programming language, the framework or the database are no longer supported by the manufacturer.
High technical debt: Over years, suboptimal solutions and workarounds have accumulated.
Fealing know-how: The original developers are no longer in the company and it is difficult to find new employees with the necessary knowledge.
Reducing flexibility: The rigid architecture can hardly be adapted to new business requirements.

The pain limit: When will action be inevitable?

An old system does not become a problem overnight. It's a creeping process. Pay attention to the following warning signals indicating that the pain limit is reached:

Warning Description

**Exploding maintenance costs * * The cost of troubleshooting and small adjustments exceed the benefits of the software by far.

**Extrem slow development * * Even the smallest changes last weeks or months and are extremely susceptible to errors. Innovation is practically impossible.

**High safety risks * * There are no more security updates for the technology used, which makes the system an easy target for attacks.

**Long integration capability * * The system cannot be connected to modern applications and cloud services or only with immense effort.

**High personnel dependency * * The entire knowledge of the system concentrates on one or a few persons whose path is an underexisting risk.

Reengineering: More than just a new paint

Reengineering does not mean simply reconstructing the software in a new technology 1:1. It is the chance to think and shape the system from scratch. A successful reengineering project typically includes these steps:

** Analysis (actual state):** Comprehensive analysis of the old application. What functions are really needed? Where are the grö

Modernizing legacy systems: When reengineering is really worthwhile