Legacy system
The term legacy system (English legacy system) designated an established, historically developed application in the field of enterprise software in computer science. Legacy this is the English word for devise, bequest, inheritance, also legacy.
Within the application landscape of a company it is mostly mainframe- based individual developments, which are often characterized by inadequate documentation, outdated operating and development environments, numerous interfaces and high complexity. The there encountered central data and function attitude extended since the client / server euphoria as outdated.
These features are the reason that the replacement of such systems often also attracts well over a desired life. Both in economic growth - as in downturns is often re-prioritized in order to avoid the high risk of default or conversion costs associated with a replacement, especially since the mere replacement of a legacy system not with a direct added value, but usually only with the saving of imputed costs ( costs for temporary or permanent failure) or opportunity costs ( lost sales is connected because of limited capacity of the legacy system ).
Fundamental problem in the replacement of legacy systems is the grown -featured. Although quite often takes place long-range replacement by powerful standard software usually remain uncovered additional functions and interfaces. These are sometimes called " golden ashtray ", but more often unique features of the grown and developed over decades software will not necessarily hold the standard software. Often a retread of the systems is already difficult because they have not been described about the history of time consistent, for example, requirements, use cases, etc.
The use of service-oriented architectures provides here meaningful approaches to cover the interface problem by the use of connectors. The exchanged systems are " encapsulated " by the outside by an intermediate layer of different source systems runs a common interface.
- IT Management
- IT architecture