Introduction to Quality Software
The software is developed by an engineer or developer, it is required by the customer, and is used by various end-users. Thus, each of them has a different perception of the quality that decides whether the software is good or not. Customers may judge by cost. The developer may judge by user satisfaction, maintainability, efficiency, portability, robustness. Users may judge by reliability, usability.
Quality Factors
According to the ISO 9126 standard, there are six quality attributes which are as follows
- Functionality: It is measured by the degree to which the software satisfies stated needs.
- Reliability: reliability of software is checked by comparing the amount of time the software is up and running.
- Usability: The usability of any software is measured by the degree to which software is easy to use.
- Efficiency: The efficiency of the software is measured by the degree to which software makes optimum utilization of the resources.
- Maintainability: It is measured by the ease with which the software can be modified
- Portability: It is measured by the ease with which software can be migrated from one environment to the other.
Attributes of Good Quality Software
In 1977, Jim McCall produced the McCall’s quality model for the US air force to bridge the gap between users and developers. He tried to map the user view with the developer’s priority. He has categorized the software quality into 3 categories.
- Product Operations: The quality criteria specified in this category talks about how easy it should be to handle and how efficiently it should use the resources and give bug-free processing and expected outputs.
- Product Revision: The quality criteria specified in this category say that the software should be easy enough to the teat, maintain, and make any changes if required.
- Product Transition: The quality criteria specified in this category says that it must be easy to transit the software on any platforms, should be able to share its code with the other languages on the platform, and try to write the code i.e. reusable in future in any other software development.
The attributes of quality software in the above categories are as below:
- Correctness: It means the required functionality and correct results. Customer satisfaction depends on the degree to which customer requirements and expectations have been met. It should provide all the functionality desired by the customer.
- Efficiency: It means the efficient use of resources. Software is said to be efficient if it uses all its resources ( memory, storage, processor) inefficient manner. The software design and architecture should be such that it gives you a response in the least processing time, using the resources in the best possible way.
- Reliability: It means bug-free execution i.e. assured performance, fully verified and validated processes, secured and safe to work when breaking down or power crisis. It should be reliable in all conditions. Reliability is measured in terms of the mean should be in all conditions. Reliability is measured in terms of the means time between failures, mean time to repair the equipment, and mean time to recover.
- Integrity: Integrity is related to extent of access to the software by unauthorized users that can be controlled.
- flexibility: The software should be developed so that if the user demands any changes in the system at the coding or testing phase. i.e. in the middle of the software development life cycle, then it should be easy to insert these challenges in the existing modules.
- Usability: It means that the software must be user friendly. The software should have hood documentation and user manual which may include the installation and the process of using the software. This makes it easy for the new to learn and operate just says studying the manual.
- Testability: It should need less effort to test the program so that it performs its intended function. As the complexity of the program increase, the efforts to test the software also increase.
- Portability: It means the software should have the ability to transfer the software from one environment to another.
- Reusability: It gives you the concepts of write once and uses many times. For example, writing functions or subprocedures to receive variable parameters. The calling code passes the value to the parameters and the called procedure processes them as needed.
- Interoperability: The software development should be so that it can interact with other products. For example, the word processor can interpolate charts from Excel or data from databases. It deals with the interface between software products over a communication network.
- Cost effective: The development of the software within cost and budget depends on efficient design and a high level of project management effort.
- Maintainability: For all the changes desired by the customer or the user, the developer has to respond fast. And this is possible only if the software design and its architecture are so chosen that changes can be carried out tin the shortest time without affecting the overall integrity of the software. The change could be to correct the mistake, expand its scope.
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