## 5 Evaluation
### Multi-Case Evaluation of DSML4 PT
#### 5.2.3 Analysis
Are there any difficulties you faced while using DSML4 PT? If so, do you have any suggestions to solve it? 6. Please write your suggestions and other comments for improving DSML4 PT's features. Considering the first question, while evaluators generally found DSML4 PT feasible, some specifically indicated that visual modeling with DSML4 PT makes IoT-based public transportation systems design easier. Two evaluators noted that DSML4 PT provides an exceptionally user-friendly structure in which both the public transportation metamodel and the instance models can be developed. Therefore, it is suitable for general use for developing public transportation software. In addition, three other evaluators stated that the well-defined structure of the language made software development easier and ensured the emergence of the quality of the public transportation system software. Considering the responses to the second question, three evaluators specifically stated that DSML4 PT was very successful in guiding developers through restrictions and controls in the development environment. With the public transportation system models created, software quality was increased in every aspect. In addition, five evaluators stated that the defined rules contributed greatly to reducing the error rate. One evaluator stated that although the DSML4 PT environment had various features, it was difficult to get used to the modeling environment. Therefore, it was decided to provide detailed information when introducing the development environment to the users and to increase the number of modeling cases. Looking at the third question, most of the evaluators stated that the built-in modeling brought by the IDE is very powerful in supporting the sustainability of system development, meaning that public transportation IoT models can be easily modified for changing system configurations. Generally, they said that the public transportation IoT domain is modeled comprehensively, including support for cloud and services. However, one evaluator specifically noted that the service/cloud viewpoint of the language was somewhat simple and could be improved, as it could not fully express the details of the service/cloud properties individually. This was because the cloud applications were represented with only one node. However, the same evaluator stated that, according to the results obtained, the applications worked properly and that a change in the metamodel for the service/cloud viewpoint would be sufficient for visual purposes only. This feedback was taken seriously and steps were considered to enrich the service/cloud viewpoint of the DSML4 PT's metamodel. Considering all the answers to the fourth question, the evaluators generally agreed that the IDE provides a simple and comprehensive design where users do not have to put much effort into preparing IoT-based public transportation system applications. Many evaluators mentioned that the viewpoint approach facilitated the design and was beneficial for the validation process and for ensuring seamless design, including the code generation phase. However, two evaluators reported that some validation rules did not give proper results. They found that even though they entered the correct information into the DSML4 PT modelling environment, the validation rules displayed incorrect information on the screen. Upon inspection of the DSML4 PT tools, it was understood that these rules were developed incorrectly when DSML4 PT was first designed. These bugs have been fixed in the DSML4 PT IDE. The most common answers given for the fifth question considered the difficulty of moving away from traditional development methods to model-driven techniques. Someevaluators, especially those who have not worked with model-driven techniques for a long time, stated that the familiarization period of MDE should be longer. As explained in the answer to the first question, training time and sample cases were increased to overcome this difficulty. Two evaluators mentioned difficulties arising from Java and Sirius installations.