A legacy application (legacy app) is a software program that is outdated or obsolete. Although a legacy ứng dụng still works, it may be unstable because of compatibility issues with current operating systems (OSes), browsers and information giải pháp công nghệ (IT) infrastructures.

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Most enterprises use legacy applications và systems that continue to serve sầu critical business needs. Typically, the challenge is lớn keep the legacy application running, while converting it lớn newer, more efficient code that makes use of current technology và programming languages.

Why are legacy applications still used?

Legacy software includes those that have been superseded by new versions; those built by developers who no longer maintain them, leaving the tư vấn team without the necessary depth of knowledge lớn vì so; & those that have sầu been patched or otherwise altered khổng lồ the point of incompatibility with current standard versions.

While a business may require a legacy application for its activities, legacy apps create complications for the IT operations teams that tư vấn them. A legacy app is frequently tied khổng lồ a specific version of an OS or coding language. For example, an application that runs on Windows 7 may not be able to run on Windows 10, despite middleware or glue code added by a development team or the OS being backwards compatible.

Furthermore, the older an application gets, the more difficult it becomes for the company using it to acquire tư vấn services.

When a vendor"s development team no longer supports a third-tiệc ngọt application, it can be difficult, or even impossible, for an operations team lớn keep the software running. Even small changes lớn a legacy system may result in slower performance, higher resource consumption & more frequent failures and crashes.

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Because software has dependencies, it"s common practice for software vendors to lớn build applications with planned obsolescence in mind. The sale of the initial version of an application may kết thúc with the release of the subsequent version. Although customer service & support generally remain available for a certain time period, the enterprise will need to lớn update the legacy ứng dụng or add another software choice to its application portfolio to provide the necessary functionality.

For example, at the start of năm 2016, Microsoft ended tư vấn for all versions of Internet Explorer (IE) prior to version 11. Users still browsing with IE 6 may continue khổng lồ vị so, but webpages will no longer be coded khổng lồ be compatible, và any bugs or errors within the program will not receive attention from Microsoft -- making all versions older than IE 11 legacy software.


There are several reasons why an enterprise must maintain a legacy or even antique application. It may be unwieldy and expensive to replace, particularly for a vertical market with specialized functionality requirements, or the operational risks of a large forklift upgrade may be too high, especially if vital data could be lost or corrupted.

Legacy application modernization and migration

Obsolete systems cannot be maintained và utilized forever; at some point, an enterprise will nâng cấp hardware, coding language, OS or the application in question. Modernization & migration involve sầu refactoring, repurposing or consolidating legacy software programming khổng lồ realign with current business needs. The goal of a legacy application modernization project is khổng lồ create new business value from existing applications.

An enterprise conducting a legacy application migration must select a new platsize for efficiency, tốc độ, stability & more dynamic capabilities. The IT organization will stand up the new application, then migrate using a staged, cut-over or concurrent (simultaneous) method.

For example, a team may look at migrating to lớn a software as a service (SaaS) approach with application program interfaces (APIs) to không tính phí the application from ties to a specific manufacturer"s OS, và to make future updates simpler. Additionally, the enterprise can redistribute the location of its application và data between proprietary data centers và public cloud computing platforms. There is also an array of tools available that allow access to legacy data.

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