ISO IEC 24570-2005 pdf – Software engineering — NESMA functional size measurement method version 2.1 — Definitions and counting guidelines for the application of Function Point Analysis.
1 Scope This International Standard: a) specifies a method to measure the functional size of software, b) gives guidelines on how to determine the components of functional size of software, c) specifies how to calculate the functional size as a result of the method, and d) gives guidelines for the application of the method. 2 Overview This clause provides an overview to the International Standard “Definitions and counting guidelines for the application of function point analysis”. The following questions are answered: What is its aim (subclause 2.1)? What is its focus (subclause 2.2)? How is it laid out (subclause 2.3)? 2.1 Objective of this International Standard The International Standard attempts to provide a theoretical framework by presenting definitions and standard guidelines. It also tries to illustrate the counting guidelines as concretely as possible by using several practical situations. 2.2 Focus of this International Standard The International Standard focuses on how the functional size of an application is determined. The International Standard does not go into any of the aspects that play a role when project budgeting is drawn up on the basis of this functional size; e.g., productivity standards and productivity attributes. This particular topic has been described in the manual “Budgeting on the basis of logical design using function point analysis”, also by the NESMA.
2.3 Organization of this International Standard The terms and concepts used in the International Standard are explained in Clause 2 and defined in Annex B. Clause 3 provides an introduction to FPA and in which the functional aspect of FPA is emphasized. It will also spell out briefly what FPA is and explains the terms that form the basis for the concept of FPA. Matters such as distinguishing between an application function point count and a project function point count are examined, just as are other various types of function point counts, the role of FPA during a project, users, and function point count. Clause 4 provides you with an overview of the position of FPA in a project and with the types of function point counts that can be carried out during the life cycle of an application. In other words, the chapter will explain when points can be counted and what information is needed minimally in order to count. The chapter will also give a step-by-step plan for carrying out a function point analysis and indicates how projects, applications, and packages should be counted. Each of these requires their approach. Clause 5 states general counting guidelines for a function point count. Clauses 6, 7, 8, 9 and 10 give successively the definitions and guidelines used to identify function types and to determine the complexity of function types for internal logical files, external interface files, external inputs, external outputs, and external inquiries. The guidelines are broken down per function type for identifying the function type concerned, for determining the number of data element types, and for determining the number of record types or referenced logical files. Clause 11 provides several practical situations and their solutions.
3.1.1 Background, purpose and application of FPA FPA was developed by A.J. Albrecht at IBM between 1974-1979 as a result of productivity research into a large number of projects. The first version of FPA was introduced in 1979, followed by adaptations based on practical experiences in 1983 and 1984. FPA is currently applied in countless organizations throughout the entire world. Experiences with the technique are exchanged in user groups: the International Function Point Users Group (IFPUG), the Australian Software Metrics Association (ASMA), the United Kingdom Software Metrics Association (UKSMA), the NESMA, and various other national user groups. FPA introduces a unit, the function point, to help measure the size of an application that is to be developed or maintained. The word “application” within the framework of FPA means “an automated information system”. The function point expresses the quantity of information processing that an application provides a user. This unit of measurement is separate from the way in which the information processing is realized in a technological sense. A function point is an abstract term and can be compared somewhat to so-called “rental points”. Rental points are based on the number of rooms in a house, the surface area of these rooms, the number of facilities the house has, and the location of the house. This then serves as a measurement for a residence offered to a potential tenant. FPA was first used to measure the productivity of system development and system maintenance after an application was built. It soon became clear that the technique could also be used to support project budgeting because the data needed for an FPA can be made available early on in a project. This FPA method may be applied to all functional domains.