ISO 9126 is the software product evaluation standard from the International Organization for Standardization. This international standard defines six characteristics that describe, with minimal overlap, software quality.
Specifying software quality for a product that has still to be developed is difficult for the purchaser or supplier. The purchaser needs tounderstand clearly and be able to communicate his/her requirements for the product to be developed. The supplier needs to be certain he/she understands the requirement, and is able to assess with confidence whether it is possible to provide the product with the right level of software quality. Consequently, ISO 9126 will serve to eliminate any misunderstanding between purchaser and supplier. Thisimprovement in communication will do away with any rework required as a result of the software product not meeting the purchaser’s requirements. Both the time taken to deliver the specified software product and the cost of development will be lower as a result of adherence to the ISO 9126 standard.
How is it used?
ISO 9126 provides the definition of the characteristics and associated qualityevaluation process to be used when specifying the requirements for and evaluating the quality of software products throughout their life cycle. (Note: This standard does not provide subcharacteristics and metrics, nor the method for measurement, rating and assessment) . ISO 9126 sets out six quality characteristics, which are intended to be exhaustive. From this it follows that each quality characteristicis very broad. Functionality is the set of attributes that bear on the existence of a set of functions and their specified properties. The functions are those that satisfy stated or implied needs.
Notes: 1. This set of attributes characterizes what the software does to fulfil needs, whereas the other sets mainly characterize when and how it does so.
2. For the stated and implied needsin this characteristic, the note to the definition of quality applies (see 3.6). 3. In a contractual environment, needs are specified, whereas in other environments, implied needs should be identified and defined (ISO 8402:1986, note 1).
Reliability is the set of attributes that bear on the capability of software to maintain its level of performance under stated conditions for a stated period oftime. Usability is the set of attributes that bear on the effort needed for use, and on the individual assessment of such use, by a stated or implied set of users.
Notes: 1. ``Users'' may be interpreted as most directly meaning the users of interactive software. Users may include operators, and users and indirect users who are under the influence of or dependent on the use of the software.Usability must address all of the different user environments that the software may affect, which may include preparation for usage and evaluation of results. 2. Usability defined in this International Standard as a specific set of attributes of a software product differs from the definition from an ergonomic point of view, where other characteristics such as efficiency and effectiveness are also seenas constituents of usability.
Efficiency is the set of attributes that bear on the relationship between the level of performance of the software and the amount of resources used, under stated conditions. Maintainability is the set of attributes that bear on the effort needed to make specified modifications. Portability is the set of attributes that bear on the ability of software to betransferred from one environment.
A key point here is that quality characteristics are the top level of an hierarchical organization of attributes: each characteristic may be broken down into quality sub-characteristics, which may themselves be further broken down. Specific evaluations or specific views of software quality may imply that some attributes are considered to be more important...