Combining visual modelling with visual programming for CORBA component development
One of the many issues that has arisen in the process of using efficient and state-of-the art techniques and software architectures is the introduction of object4componentoriented methods. Another general trend is the integration of visual elements and techniques in tool development environments. This thesis identifies several approaches for improving the effectiveness of current development by introducing different visual programming techniques. One promising idea, in order to decrease the complexity of software development and to improve the efficiency for novice and inexperienced users, is the creation of a complete visual system that makes use of either visual modelling or visual programming techniques and thus reduces the gap between different representations and paradigms. The goal of this dissertation is to investigate why there has been little research in the field of visual object-oriented programming and the integrated combination of visual modelling with visual programming in order to find new ways to improve this situation. Of specific interest is the improvement and support of component-based development, as this will play a central role in modern software development in the near future. A prototype system for the development of CORBA components has been developed that integrates visual programming with visual modelling. In particular, a new visual programming language called VOOPL has been invented. The language is based on the processor idea, which is directly related to a visual control-flow paradigm. The visual modelling approach is based on standard UML models (namely class diagrams plus specific stereotypes). The system has been tested by informal usability trials. The results of evaluations indicate that this is an effective approach for novice and inexperienced users but less so for professional users. One key problem identified is the lack of a standardised visual programming language that would decrease the learning curve for a complete visual (object-oriented) approach. The visualisation of code elements through the use of so-called processors has proven to be accepted by users. Processor code is useful for showing the overall code structures but less efficient for entering control logic. Therefore, a hybrid approach (i. e. the combination of visual and textual programming) is suggested. The findings of this research clearly show that there are benefits when combining visual modelling with visual programming. Combining Visual Modelling with Visual Programming for CORBA Component Development Page 3 Acknowledgments I would like to thank Paul Reeves and Sarah Lingard for their support and fruitful discussions during the long period of research. Special thanks to my supervisors Paul Luker and Michael Callaghan for giving me the opportunity to carry out this PhD work. I am grateful for their support and motivation. During the last two years I have benefited tremendously from the many discussions with my colleagues at Dresdner Bank AG, Frankfurt/Main (Germany). They taught me what is important for real-life projects and broadened my horizons in many different ways. In addition, I would like to thank those colleagues who participated in the evaluation studies. Finally, the work would have never been possible without the encouragement and tolerance of my wife Anja Zink-BOhler and my lovely children. Declaration I hereby declare that this PhD thesis is a record of work undertaken by myself and is not being submitted concurrently in candidature for any other degree. FB uer Lei ster February 27,2001 Combining Visual Modelling vAth Visual Programming for CORBA Component Development Page 4