ISO / IEC 9126

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The ISO / IEC 9126 standard is one of several models for ensuring software quality. With its criteria, it relates exclusively to the quality of the software as a 'product' ( product quality ), not or only indirectly (via the results) to the quality of the software development processes ( process quality ).

This ISO standard has been incorporated into the ISO / IEC 25000 standard and has been replaced by this same standard.

Quality features

The quality criteria for software as a product according to ISO 9126

The following quality features are listed (partial features are only listed as suggestions in the appendix to the standard):

  • Changeability / maintainability : How much effort does the implementation of given changes to the software require? - The effort required to carry out specified changes. Changes can include corrections, improvements or adaptations to changes in the environment, requirements or functional specifications.
    • Analyzability: Expenditure to diagnose defects or causes of failure or to determine parts that need to be changed.
    • Conformity: The degree to which the software complies with standards or agreements on changeability.
    • Modifiability : Effort to implement improvements, to correct errors or to adapt to changes in the environment.
    • Stability: the likelihood of unexpected effects of changes occurring.
    • Testability : the effort required to test the changed software.
  • Usability : How much effort does the use of the software require of the users and how is it assessed by them? - Effort required for use and individual assessment of use by a specified or assumed user group. See also software ergonomics .
    • Attractiveness : The application's appeal to the user.
    • Usability : effort for the user to operate the application.
    • Learnability: effort for the user to learn the application (for example operation, input, output).
    • Conformity: The degree to which the software meets standards or usability agreements.
    • Comprehensibility: effort for the user to understand the concept and the application.
  • Efficiency : What is the relationship between the performance level of the software and the resources used? - Relationship between the level of performance of the software and the scope of the operating resources used under specified conditions.
    • Conformity: The degree to which the software meets standards or agreements on efficiency.
    • Time behavior : response and processing times as well as throughput during function execution.
    • Consumption behavior : Number and duration of the resources required to fulfill the functions. Resource consumption such as CPU time, hard disk access, etc.
  • Functionality : To what extent does the software have the required functions? - Presence of functions with defined properties. These functions meet the defined requirements.
    • Appropriateness: Suitability of functions for specified tasks, for example task-oriented composition of functions from sub-functions.
    • Security : Ability to prevent unauthorized access, both accidental and deliberate, to programs and data.
    • Interoperability : Ability to interact with given systems.
    • Conformity : Ability of the software product to comply with standards, conventions or legal provisions and similar regulations related to functionality.
    • Compliance: Features of software that cause the software to comply with application-specific standards or agreements or legal provisions and similar regulations.
    • Correctness : Delivering the correct or agreed results or effects, for example the required accuracy of calculated values.
  • Portability : How easily can the software be ported to another environment? - Suitability of the software so that it can be transferred from one environment to another. The environment can be an organizational, hardware or software environment.
    • Adaptability: Ability of the software to adapt it to different environments.
    • Interchangeability: Possibility of using this software instead of a specified other in the environment of that software, as well as the effort required for this.
    • Installability: the amount of effort required to install the software in a defined environment.
    • Coexistence : Ability of the software to work alongside another with similar or identical functions.
    • Conformity: The degree to which the software meets standards or transferability agreements.
  • Reliability : Can the software maintain a certain level of performance under certain conditions over a certain period of time? - Ability of the software to maintain its level of performance under specified conditions for a specified period of time.
    • Fault tolerance : the ability to maintain a specified level of performance in the event of software errors or non-compliance with its specified interface.
    • Conformity: The degree to which the software meets standards or agreements on reliability.
    • Maturity: Low frequency of failure due to fault conditions.
    • Recoverability: the ability, in the event of failure, to restore the level of performance and recover the data directly affected. The time and effort required must be taken into account.

See also

Individual evidence

  1. ISO-Store ISO / IEC 9126-1: 2001 [1] This standard has been revised by: ISO / IEC 25010: 2011
  2. a b Helmut Balzert textbook of software technology z. B. in [2]