Object-Oriented Software Development with UML - UNU-IIST ...

The system should do 4 X 530 Understanding requirementsSystem functionsSystem functions are what a system is supposed to do.To verify that some X is indeed a system function, it should make sense in the following sentence:For example, “ease-of-use” does not fit in the verification sentence. Thus, system qualities of this kindshould not be part of the functional requirements specification.The system’s functions should be categorized in order to priorities them or to avoid from missing them.Categories include¢Evident functions such function should be performed, and user should be cognizant that it is performed.¢Hidden functions should be performed, but not visible to users. This is true of many underlyingtechnical services, such as save information in a persistent storage mechanism. Hidden functions areoften incorrectly missed during the requirements gathering process.¢Frill functions are optional; adding them does not significantly affect cost or other functions.In the presentation of the functions,they should be divided into logical cohesive groups,¢each function should be given a reference number that can be used in other documents of the devel-¢opment,¢the category that a function belongs to should be indicated.For the POST application, we present two groups of the system functions, the basic functions and thefunctions related to payment. These functions serve as a set of representative sample, rather than a completelist.Basic functions of the POST systemReport No. 259, July 2002UNU/IIST, P.O. Box 3058, Macau