Software informational articles

Cosmic: a small development on the symons approach - software


The COSMIC FP (function point) software attribute metric, is no longer 'proposed' but an definite arrangement in use and globally recognised, but MarkII, like other older systems, is not recognised anywhere, and, even in the UK is in decline if not in point of fact dormant, so this consideration is before now over.

Historically, from my inadequate appreciation of the situation, it seems that first there were upwards of 35 variants of do point style metrics until the ISO urban criteria for a adequate solution, ISO 14143: Parts 1 to 5 (1995-2002):

The COSMIC group reviewed offered functional size measurement methods, specifically the work done in the late 80's by Charles Symons in the UK. The aim was to build up on Albrecht's size index (IFPUG FPA)

As acknowledged in many sources, the most central appear of the COSMIC fashion is that, contrasting Mark II, it was urbanized alongside the materialization of the newer software applications that did not exist when Mark II was devised, thus being fitting with current software manufacturing concepts and disparate the prior metrics, this fashion was intended to be congruent with the ideas from structured assay and design.

Because of these two features, COSMIC has Full ISO acknowledgment and is has inherent flexibility for a wider range of software, this flexibility also makes the metric less aware to mistakes all through breakdown than is typically the case with the Mark II metric which does not have the same capacity to capture size from compound viewpoints

Function point style metrics estimation algorithms be of special concern to applying a set of rules and procedures to a given piece of software as it is perceived from the perspective of its Functional User Requirements. As size procedures are not very precise, this gives a conceal of art to what is in air a guessing game.

The answer being that while Mark II can be used for sizing of the GUI and real-time systems which did not exist when it was formed only after big adaptation, but which itself creates difficulties of analysis due to conflicting procedures and rules.

An chief issue with the Mark II approach is that the "functional gears of the fashion are awkward or subjective to interpret" 6, altered measurers will get another results.

The COSMIC fashion of sizing the functional necessities of software has been permitted as an Worldwide Average (ISO/IEC 19761:2003). and contrasting the earlier variations, COSMIC is the first approach to be considered by an worldwide team, as different to being the consequence of one assistant professor or entity. This is a affirmative for the reason that it will help standardisation which will in turn convalesce repeatability of the measurement.

The most central difficulty to Act point attitude is that "it takes numerous days to learn behave point as well as and more time to develop into proficient. This clear has incomplete the pool of skilled counters. " 3 Many of the sources I looked at incorporated warnings such the next "Function Point Assay ought to be performed by educated and qualified personnel. If Affair Point Examination is conducted by unqualified personnel, it is cheap to fake the assay will done incorrectly. " 4

Function point methodologies are considered about the claim of composite rules and procedures that conclusion in a arithmetic "value of a quantity"2 instead of the functional size of the software.

Unlike the Mark II method, COSMIC requires an extra step to associate layers' beforehand indentifying the approach boundary, nevertheless this deal with enables the breakdown to advance bank account for the inner workings of a composite approach and reduces the probability of gone functions.

The broad consensus from the resources that I have read is that essentially the measurement energy for COSMIC is alike to that desired for customary sizing methods. But contrasting the other methods, COSMIC functional size approach is 'easy' or 'reasonably easy' to apply.

This is in part due to the abstraction of the mechanical adjustment factors from the specifications and oversimplification of the transactional functions rules and terminology. Fore example, using Mark II "a affair is not a point but for certain rules are satisfied"3. Where as COSMIC as well as rules consist of "three core rules that ascertain which observations constitute a point"3.

An central aspect in broad ease of use is the underlying arithmetic framework for quantifying and abridgment behave points but which involves a loss in in a row when summarized into unadjusted affair points.

Using COSMIC there is no break free including of files (ILF and EIF) and is Ratio/Absolute. We would associate for each functional process, the subprocesses (entry, exit, read, write); The measurement Viewpoint allows "all functions to be built-in in the size measure" different in Mark II method, then apply measurement do as follows; FP Size = Sum(number of Entries ) + Sum(number of Exits) + Sum(number of Reads) + Sum(number of Writes)

"The size of a functional deal with is the sum of its data appointments (entry, exit, read, write) and the size of a piece of software is the sum of the sizes of all of its functional processes. " 6.

Due to the hypothesis of data arrangements as conflicting to Commonsense Files once per arrangement used in the Mark II, COSMIC consequences in amore precise size calculate for the difficulty of giving out stored data.

For example, in the given case above it is not awkward to count on the fill in array transaction input to the Catalog item creature to be production at some point in the transaction and develop into part of the input the inventory_item article this is in rank is lost.

Under Mark II rules, it is counted as an input once when the data crossed the attention boundary, but not as an input in the Invontary_item being since the data does not leave the attention boundary again at that point.

For the fill in list transaction under Mark II we can a UFPI count of (0. 58*9) + (1. 66 * 4) (0. 26*1) = 12. 12, under CosMIC we would come at an corresponding count of 3+5+4 =12

In conclusion, the fact that act points are not (yet) a accurate amount of an application, COSMIC does represents an development over the IFPUG and other '1st Generation' FSM Methods. Measurement of functional sizes can be more plausible, easier to make and repeatable.

However functional size measurement equipment must keep evolving to meet marketplace needs. definitely I would think that this is too subjective to be counted as a "measure". For instance, I face-to-face know over 120 software developers at 20 another companies, and insignificant person had ever heard of Behave Points beforehand I did.

The accumulation in COSMIC of the hypothesis of in-house layers, for advance identification of constituent to element interaction allows for more accomplish analysis, and is absent from MarkII. What is still looked-for is a definite banner for passable precision and an effectual way to depict the exactness of the do points which could be achieved in fact all through advance guidelines. Due to the fact that COSMIC is free and affable everyplace in the world it is more expected to continue to exist and evolve, contrasting MarkII which is UK only, and proprietary.

[1] Abran, Alain, Robillard, Pierre N. , "Function Points : A Study of their Measurement Processes and Scale Transformations", Journal of Systems and Software, May 1994, pp. 171-184.

[2] Steve Neuendorf. (2001) Let Size A = X Affair Points, Online, http://www. serv. net/~steve/Let%20Size%20equal%20FP. htm, October 22 2004.

[3] Steve Neuendorf. (2001) Evolving Behave Points, Online, http://www. stsc. hill. af. mil/crosstalk/2001/02/fischman. html, October 25 2004.

[4] Symons, C. R. , 'Function Point Analysis: Difficulties and Improvements', IEEE Trans Software Eng. , vol 14, no. 1, Jan 1988

[5] Total Metrics. (2001) Behave Points FAQs, Online, http://www. totalmetrics. com/cms/servlet/main?Subject=Content&ID=165, October 22 2004.

[6] Unkown. (2002) Compensation of the COSMIC-FFP method, Online, http://www. cosmicon. com/advantagecs. asp, October 25 2004.

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