STANDARDSSOF T WARE TECHNOLOGIES Formality, Agility, Security, and Evolution in Software Development

Combining formal and agile techniques in software development has the potential to minimize change-related problems. C omplex systems have always been problematic with respect to software development. Simplic-ity is desirable, but the reality of dealing with a customer means that requirements are likely to change, resulting in a corresponding loss of elegance in the solution. A good software engineer will design with the knowledge that the system is likely to evolve over time, even if the exact nature of the changes is unknown. Such exper-tise only comes with experience and an innate aptitude, especially in the understanding and use of abstraction. Software engineering ap-proaches such as object orientation and modularization—for example, the Z notation schema construct— can help minimize change-related problems if used carefully, follow-ing standard patterns of use. Formal methods have been advocated for im-proving the correctness of software systems,1 and agile software develop-ment has been promoted by the Agile Manifest