COSMIC is, like FPA, a method of the Functional Size Measurement family that is conformant with the ISO/IEC 14143 standard. Whereas FPA has been designed to measure business software only, COSMIC is designed to measure any kind of software in any layer of a software architecture, at any level of decomposition. For instance, within one organization COSMIC is in use for sizing business software, SOA services, embedded software, real-time software and the software of ATM’s, all with the same set of concepts.
COSMIC’s sizing approach, based on fundamental software engineering principles, is the same for all these kinds of software: identify the functionality of the piece of software to be measured, as reflected by the four types of data movements entry, exit, read or write in its Functional User Requirements and assign 1 COSMIC Function Point (CFP) each.
As a function can encompass many data movements, it can have any whole number of COSMIC Function Points, rather than the three possible values that FPA uses to classify the functional size. This open-ended measurement scale of the COSMIC method means that sizes of software at different levels of decomposition can be easily aggregated, if needed, following simple rules. This is very important for measuring the output of Agile projects at any level from sprints, iterations and releases up to whole systems.
The COSMIC method can also correctly measure the size of required changes to software. (FPA can only measure the size of a piece of software to be changed; it cannot measure how much must be changed.)
The number of function points that FPA uses to size Input, Output and Inquiry functions was determined in 1975 in order to reflect the development effort of these business functions at that time. It is therefore questionable that these values still have a valid meaning for the wide variety of software functionality as it is being created today.
See also the Advantages page.
Posted in: The COSMIC method