The danger of legacy
Today, software development takes place in a highly competitive environment. This introduces several significant risks that may affect business performance and one of the most dangerous is excessive efforts to maintain legacy technologies. Although businesses may be hesitant to make investments in new technology, the true cost of legacy technology far outweighs the investment. Because legacy applications cost more to run and maintain, they make the business highly inefficient, increases operational costs and system downtime. Legacy technologies are also extremely vulnerable, because many of these outdated systems are no longer supported by the manufacturer. Another problem with using outdated technology is that most legacy systems are incompatible with newer systems.
However, scrapping legacy systems and replacing them with more modern software involves significant business risks. Most managers try to minimize risks and therefore do not want to face the uncertainties of new software systems. Replacing a legacy system is a risky business strategy for a number of reasons. There is rarely a complete specification of the legacy system. The original specification may have been lost or not written in sufficient detail. Therefore, there is no straightforward way of specifying a new system that is functionally identical to the system that is in use.
New software development is itself risky so that there may be unexpected problems with a new system. It may not be delivered on time and for the price expected.
Keeping legacy systems in use avoids the risks of replacement but making changes to existing software usually becomes more expensive as systems get older. There are several reasons that lead to an increase in the complexity of system maintenance. First of all, different parts of the system may be implemented by different teams. There is, therefore, no consistent programming style across the whole system. Replacement of developers is a completely normal business process, but it is necessary to strictly adhere to the code style and follow the architecture guidelines.
To eliminate the risk of obsolescence of a programming language or framework, it is desirable to divide the application into separate services with a minimum number of dependencies. If necessary, any of these services can be rewritten using new technologies and this will in no way affect the functionality of other parts. In addition to dividing into separate services, the use of modular architecture and the CQRS principle allows you to divide functionality within a service.
During the development process, it is necessary to allocate time for creating and updating the documentation so that it does not become outdated. All documentation should be structured and it is advisable to use specialized tools for writing and storing documentation. All business processes should be described in the form of UML diagrams.
The system may have been optimized for space utilization or execution speed rather than written for understandability. This causes particular difficulties for programmers who have learned modern software engineering techniques and who have not been exposed to the programming tricks that have been used. In the long run, clear and easily modifiable code is always preferable to an optimized but overcomplicated solution.
Adherence to uniform standards, division into independent services, timely updating of documentation allows you to gradually develop the product without the need to rewrite it completely.
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