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How to define and use the Quality Model.
In order to be able to implement Code Quality Control procedures, it must be possible to measure the quality and verify these measurements against pre-defined values. Software metrics are entities which represent characteristics of software and which can be measured (through static analysis). In the QStudio framework, the quality of the the source code is expressed by combining software metrics in the Quality Attribute Tree (see Concepts). The QStudio Quality Model is a collection of software metrics in which for every metric a number of indicators is defined. From the use of these indicators, they can be divided into 2 groups:
Quality compliance
As part of every inspection run a check is performed to determine whether the quality of the source code complies with the quality standard. A software module complies with the standard when the measured values (from the analysis) of all software metrics are less or equal than the corresponding compliance value from the standard. Existing software (prior to QStudio usage) will generally not comply with the standard. In order to incorporate existing software in the QStudio quality control procedures the 'relative compliance' criterium is introduced. This is the percentage which the quality of the (changed) software has to increase with each update i.e. released (checked in/controlled) instance. A software module complies relative with the standard when the absolute compliance criterium is NOT met but when the measured values (from the analysis) of all software metrics improved at least a pre-defined improvement-percentage, compared to the corresponding values from the previous released (checked in/controlled) instance of the software module (from last Formal inspection run). Relative compliance detection can only occur when:
Quality compliance is used in the following QStudio functionalities:
Quality rating
Besides using the compliance criterium, to express and control the quality of the source code, the mechanism of 'ratings' can be used. Through such a mechanism a high level overview can be obtained on the overall status of the quality of the source code. The ratings-mechanism is based on the fact that the values of software metrics have to meet a maximum i.e. the lower the value the better is the quality (on the aspect expressed by the metric). Within the QStudio Quality Model 4 ratings are defined :
| Good | measured value between 0 and first rating level |
| Sufficient | measured value between first- and second rating level |
| Suspicious | measured value between second- and third rating level |
| Bad | measured value higher than third rating level |
Quality rating is incorporated in the model through the indicators (see View standard) :
Quality rating is used in the QStudio functionality: WUI - Ratings view
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