Model-based Functional Size Measurement

Function Point Analysis (FPA) is the most widely used method for measuring the size of software requirements, usually for the purpose of cost estimation. Unfortunately, FPA is affected by several drawbacks: it must be performed by specifically skilled personnel, it is expensive, and the resulting measures are subject to high variability. In order to solve –at least partially– these problems, researchers have proposed to base FP counting on UML models. However, models built without having FPA in mind hardly provide the required information at the proper detail level, so that the measures of the models tend to vary accordingly. On the contrary, building models that are suitable for FPA generally requires additional notations, skills and effort, thus partly spoiling the advantages of the approach. This paper illustrates a technique for building FPA-oriented UML models that do not need to include more information than usually required by the development process, and are easy to measure. As a result, FPA can be performed in a seamless way, while yielding reliable results. The proposed technique was validated by means of a controlled experiment and a set of pilot applications, which are also briefly described in the paper