How to evaluate the quality of the software
裴华明 (Reprinted from Computer World Network)
We often say that a certain software is easy to use, a software function is full, the structure is reasonable, and the level is clear. These expressions are very vague, used to evaluate software quality is not exact enough, and cannot be used as a basis for enterprise purchase software. For enterprises, development units develop an application system in accordance with the needs of the enterprise, complete and transferred on time, and the system correctly execute the functionality of the user, only satisfying these is far less than enough. Because companies are in the process of introducing a software process: ● Customized software may be difficult to understand, difficult to modify, during maintenance, during maintenance, the company's maintenance cost is greatly increased; ● Enterprises have doubts about software quality, The evaluation software quality does not have an appropriate indicator, understanding the software reliability and functional indicators; ● Software developers lack historical data as a guide, all about progress and cost estimates are rough. Because there is no practical productivity indicator, there is no data on the software development process, and the company cannot accurately evaluate the quality of work of the developer. To this end, it is necessary to understand the quality evaluation system of the software. B.Boehm and R.Brown in the United States have proposed three levels of evaluation metrics: software quality elements, guidelines, metrics. Subsequently, G.Mruine proposed its own software quality metric SQM technology. Boeing has adopted SQM technology during software development, and Japan's NEC has also proposed its own SQM tool, which is SQMAT, and has achieved cost control and progress arrangements. A good effect. The first layer is software quality element, software quality can be broken down into six elements, which is the basic feature of software: 1. Functionity: The functionality implemented by the software meets the degree of user demand. Functional reflects the extent that the developed software meets the needs of users, that is, whether the functionality required by the user is fully implemented. 2. Reliability: Under the specified time and conditions, the software can maintain its performance level. Reliability is an important quality requirement for some software. In addition to reflecting the extent to which the software meets the normal operation of user needs, and reflects the level of continuing operation during failure. 3. Easy to use: For a software, user learning, operation, preparation input, and understanding, the extent of effort is made. Easy to use reflects whether the user is friendly, that is, if the user is convenient when using this software. 4. Efficiency: Under the specified conditions, the effectiveness of the computer resources (including time) required for some feature are implemented using the software. Efficiency reflects whether there is any waste of resources when completing the functional requirements, and "capital" quot; this term has a wide range of meanings, which includes memory, existence, channel capability and processing time. 5. Repairability: In a runoffed software, in order to meet the user's needs, environmental changes, or software error occurs, the corresponding modification has made efforts to make a corresponding modification. The maintenanceability reflects the corresponding corresponding to the software system when the user's demand change or the software environment is changed. Easy to modify. An easy-to-maintain software system is also a software that is easy to understand, easy to test and modify to correct or add new features, or allow operation in different software environments. 6. Portability: from one The computer system or environment is transferred to another computer system or environment. The second layer is the evaluation criterion and can be divided into 22 points.
Including accuracy (software attributes required for accuracy when calculating and output); robustness (software attributes that can continue to perform and restore system); security (prevent software from accidentally or deliberate access, use , Modify, destroy or leak software attributes; and communication validity, processing effectiveness, effectiveness, operability, trail, completeness, consistency, traceability, visibility, hardware system independence, software Systematic independent, expandability, publicity, modular, clarity, self-descriptive, simplicity, structural, product file completeness. The relationship between the evaluation criteria will reflect a single software quality element, the relationship between software quality factors and evaluation criteria is shown below: The third layer is metrics: analysis, summary design, detailed design, implementation, assembly test, confirmation test And maintenance and use of seven stages, a questionnaire for each stage is developed to achieve the quality control of the software development process. For enterprises, whether it is customized, or the second development after the purchase software, understanding and monitoring the progress of each link of the software development process, the product level is critical, because the software quality is high, it is large Depending on the degree of user participation. Requirements here: (1) For different types of software, system software, control software, management software, CAD software, educational software, network software, and different sizes of software, focus on quality requirements, evaluation criteria, metrics Differences should be different. For example: software quality assurance and evaluation activities have their different side priorities. In demand analysis, summary design, detailed design and its implementation stage, main evaluation of software demand is complete, whether the design completely reflects the demand and whether the coding is simple, clear. Moreover, there is a specific metric work table, which consists of a specific metric, and can gradually obtain metrics, the score of the elements, and evaluate it on this basis. This is very suitable for companies working with software developers. (2) The fundamental purpose of metrics in each stage of software quality is to control cost, progress, improve software development efficiency and quality, but currently large-scale software companies are not much in my country, most software development units The lack of software quality assurance and software quality evaluation, so companies can entrust professional institutions to participate in helping software quality control and guarantee. For example, MeetRTQS companies in the United States is specially engaged in software quality evaluation, while Japan's NEC is conducted by software quality assurance organizations within the company. (3) Enterprise chooses software suppliers, developers, need to investigate whether the company has established its own software quality metrics and evaluation data, whether there is software related to the industry in the industry in the database, whether there is related development experience. Software is increasing in the enterprise, there are four ways to obtain software, develop, direct outgoing, proderation, and cooperation with software developers. It is most common in cooperation development, because this approach can meet the unique business process of business, more targeted. Whether the software developed is easy to use, how is the quality, you need to use the quality measurement standard above. There are currently a better software quality evaluation platform, such as the SQTF of the Shanghai Computer Software Review Key Lab, is based on the type and characteristics of the measured software, for software six quality characteristics, 21 subsystems, choose different metrics, The evaluation system formed, according to this, qualitative, quantify, independent technical testing of the test software, focusing on the use of numbers, more scientific. For example, enterprise purchase financial software, first of all, to meet functionality, followed by reliability.
