Legacy System - Alternative View

Alternative View

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There is an alternate point of view — growing since the "Dot Com" bubble burst in 1999 — that legacy systems are simply computer systems that are both installed and working. In other words, the term is not pejorative, but the opposite. Bjarne Stroustrup, creator of the C++ language, addressed this issue succinctly:

"Legacy code" often differs from its suggested alternative by actually working and scaling. —Bjarne Stroustrup

IT analysts estimate that the cost to replace business logic is about five times that of reuse, and that's not counting the risks involved in wholesale replacement. Ideally, businesses would never have to rewrite most core business logic; debits must equal credits — they always have, and they always will. New software may increase the risk of system failures and security breaches.

The IT industry is responding to these concerns. "Legacy modernization" and "legacy transformation" refer to the act of reusing and refactoring existing, core business logic by providing new user interfaces (typically Web interfaces), sometimes through the use of techniques such as screen scraping and service-enabled access (e.g., through Web services). These techniques allow organizations to understand their existing code assets (using discovery tools), provide new user and application interfaces to existing code, improve workflow, contain costs, minimize risk, and enjoy classic qualities of service (near 100% uptime, security, scalability, etc.).

The reexamination of attitudes toward legacy systems is also inviting more reflection on what makes legacy systems as durable as they are. Technologists are relearning the fact that sound architecture, practiced up front, helps businesses avoid costly and risky rewrites in the first place. The most common legacy systems tend to be those which embraced well-known IT architectural principles, with careful planning and strict methodology during implementation. Poorly designed systems often don't last, both because they wear out and because their reliability or usability are low enough that no one is inclined to make an effort to extend their term of service when replacement is an option. Thus, many organizations are rediscovering the value of both their legacy systems themselves and those systems' philosophical underpinnings.