Quality of business models expressed in BPMN

Context. The quality of business process models is important in the area of model-based software development. The overall goal of this study was to develop and evaluate a model for assessing the quality of models (Process Diagrams) in Business Process Model and Notation (BPMN). The model was an instantiation of the developed metamodel that adopt ISO/IEC 1926. Objectives. The objectives of the thesis were to propose, implement and evaluate a model for quality assessment of business process models in BPMN. The model was intended to help practitioners to check the quality of their BPMN models and provide meaningful feedback on whether the business process models are of good or bad quality. First objective was to develop a metamodel of models for quality assessment of business process models in BPMN, and later the model that in an instantiation of the metamodel. Within the model, the objectives were to propose the relevant quality characteristics, quality metrics, quality criteria and quality functions. Finally, usefulness of model for quality assessment of business process models in BPMN was to be evaluated. Methods. The methodology was driven by essential elements of the model for quality assessment of business process models in BPMN. This is: quality characteristics, quality metrics, quality criteria and quality functions. In the beginning the metamodel of the model was developed based on the ISO/IEC 1926 standard. Later, in order to identify quality characteristics of models existing in the literature, a systematic literature review was conducted. Quality characteristics explicitly relevant to BPMN were compared against each other and selected. Overlapping quality characteristics relevant to BPMN were merged. Next, in order to obtain quality metrics that measure aspects of models of business processes, a literature review was carried out. The literature review was restricted by a proposed set of selection criteria. The criteria were questions that every relevant literature describing quality metrics must affirmatively answer in order to identify only metrics that were able to be assigned to identify quality characteristics. If the chosen quality metrics needed to be changed or adjusted for the sake of better results, the author added changes or adjustments and provided rationale for them. Next, in order to obtain quality criteria, values of the quality metrics were gathered through measuring a repository of BPMN models. The repository was gathered as a preparatory work for the thesis and it consisted of models of varying quality. Manual measurement of quality metrics for each BPMN model from the repository could not be done within a reasonable amount of time. Therefore, a tool to automatically calculate metrics for BPMN models was implemented. The quality criteria were proposed based on the results from interpretation of the values using statistical analysis. Later, quality functions that aggregate values of the metrics were proposed. The complete model was next integrated into the tool so that it could assess a quality of real BPMN models. Finally, the model for assessing the quality of business process models in BPMN was evaluated for usefulness through a survey and survey-based experiment. Results. A metamodel of models for quality assessment of business process models in BPMN was proposed. A model for the quality assessment of models in BPMN was proposed and evaluated for usefulness. Initial sets of quality characteristics of models were found in the literature and quality characteristics that were relevant to BPMN were extracted. Quality metrics that measure aspects of models were found and adjusted to the BPMN notation. Quality criteria that state how values of quality metrics can be classified as good or bad were provided. Quality functions that state if quality characteristics are good or bad for a chosen BPMN model were provided. Finally, a tool that implements the model for quality assessment of models in BPMN was created. Conclusions. The results of the survey and survey-based experiment showed that the proposed model for quality assessment of models in BPMN works in most cases and is needed in general. Additionally, the elements of the model which should be corrected were identified. Contacted users of BPMN expressed a will to use the suggested tool associated with the model for quality assessment of business process models in BPMN