User Guide
1.0 Introduction
From 1940s (start of the software era) until today, software development and maintenance have become increasingly more difficult and costly for the organizations due to many reasons. It has therefore been of growing importance for software engineering management to be able to predict the right cost of developing, maintaining, and modifying software, in order to keep projects under control and prevent budget and schedule overruns. Software estimation is about estimating the effort (most of the times it means cost in term of money) and time required to develop or modify a software system.
For this purpose various methods of software size measurement have been proposed (such as COSMIC-FFP, IFPUG, and MarkII). Even that, all these methods have the same objectives, their designs are vastly different, and of course, their results are different as well. This creates confusion and makes difficulties for industrial organizations, which rely more and more on software and the need to manage them. All these situations create very difficulties for them to make the choices that best suit their requirements, as they have neither the time nor the analytical tools to verify each method individually. In 1998, the COSMIC was formed, to design and bring to market a new generation of software measurement methods. The first functional sizing method should be designed to work equally well for traditional data-rich business software as for control-rich or real-time software. It was not designed to measure functionality of algorithm-rich software. The COSMIC-FFP measurement method is designed to be independent of the implementation decisions embedded in the operational artifacts of the software to be measured. To achieve this characteristic, measurement is applied to a generic model of the software Functional User Requirements onto which actual artifacts of the software to be measured are mapped. COSMIC-FFP is a method for measuring the size of software.
The COSMIC-FFP software model captures the concepts, definitions and relationships (functional structure) required for a functional size measurement exercise. Depending on how the FURs are allocated, the resulting software might be implemented in a number of pieces. While all the pieces exchange data, they will not necessarily operate at the same level of abstraction. The COSMIC-FFP method introduces the concept of the software layer to help differentiate levels of abstraction of the FURs.
Figure 1.0 COSMIC-FFP measurement process model (Ho, Arban and Oligny, 2000)
The new COSMIC-FFP method of sizing the functional requirements of software has been approved as an International Standard (ISO/IEC 19761, 2003). For software developers, the ability to measure a size of software from its functional specifications, early in the life of a project is a first key step for estimating development effort. And then the size measured is independent of the technology used, this provides a key component for software project performance measures such as productivity, etc.
COSMIC-FFP was designed to meet these challenges, from the outset to measure the functional size of real-time, multi-layered software such as used in telecoms, process control, operating systems, and business application software as well so we can say it cover the almost all field of software production. Such wide applicability is unique and a big breakthrough for the world of software project performance measurement and estimation (Azzouz and Abran, 2004).
This is user guide to estimate the approach need to develop for a particular system, by the help of the COSMIC-FFP; the system can be an e-commerce web sites or multi-tier architectures etc (list of the field is given below where COSMIC-FFP is applicable). The guide should enable an effort estimator to use COSMIC-FFP to estimate the effort required for the development of a particular system (COSMIC, 2003).
1.1 Application of COSMIC-FFP Method
The COSMIC FFP method has been used for the sizing of a remarkable variety of software, for different purposes, most of them are in connection with performance measurement and estimating.
- Business application software in banking, insurance, utilities etc
- Infrastructure software supporting business applications, i.e. web-services, messaging and n-tier architectures
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Avionics software of a major fighter aircraft system and other defence systems
- Telecoms switching systems, mobile phone SMS messaging
- Comparing the functionality of mobile phone handsets
- Engine control and fuel injection systems
- Paper copier systems
- Size measurement of basic re-usable Objects
- Text parsing software
- Safety-critical software for a US Regulatory Commission (COSMIC, 2003).
2.0 Summary
In this user guide I analyzed three systems two of them are single tier business application and one is multi tier business application. First of all I defined the boundary of these system, extract the functional user requirement, mapping phase, which was quite difficult for me in this user guide, measurement of functional process and in the last comparison between CSMIC-FFP and MK11. I did measure the function point for three systems. According to my understanding I got thirty one data movement (Cfsu) in first case in five functional process, twelve in second case and also twelve data movement (Cfsu) in third case. I also discussed some weak point of COSMIC-FFP in comparison.
