The catalogue of design patterns from [Gamm94] contains about twenty design patterns and their mutual relationships. In this paper, we organize these relationships into different categories and revise the design patterns and their relationships. We are then able to arrange the design patterns in different layers. The results simplify the understanding of the overall structure of the catalogue, thereby making it easier to classify other design patterns, and to apply these design patterns to software development.

Most current object-oriented design techniques and approaches focus on the new development of a software system, without regarding the reorganization of existing systems at all. But many people point out, that after the initial design and implementation of an object-oriented system, the system must often be reorganized in order to get a cleaner design which is easier to understand, modify and extend. This paper presents experiences in the reorganization process of a hypermedia application, in which the new design pattern approach [Gamm93] was extensively used.

In building process models based on objects, we identify a gap between object capabilities and the process world. To overcome this problem, a level of abstraction, role, above the object level, similar to pattern structure, has been defined. We have represented roles in different levels of abstraction containing CRC cards, formalised CRC (CRC plus path expressions), Petri nets, and encapsulated structures to provide a pattern representation of roles. Since it is important to understand a pattern before reusing it, a representation method to encapsulate a solution for a pattern based on roles which rely on cooperative objects is suggested. An approach to refine the representations also helps to specify the exact semantics of such representations. 1 Introduction The primary motivation for this research was experimentation with the design of process models based on the collaboration of cooperative objects. When exploiting objects for this purpose, we have treated process models like othe...

Recent trends focusing on process technology applied in different domains confirm the obvious fact that a quality product can only be the result of a quality process. One of the basic requirements for improving the quality of a process is to manage its complexity by means of modelling techniques using different levels of abstraction. A simple yet powerful view for modelling a process is to represent the behaviour of its identified agents in terms of their activities and interactions with each other. To implement such a view, object-oriented modelling can be exploited for modelling the agents of a process in terms of objects and representing the dynamic behaviour of objects through the message passing and concurrent execution of these objects within a process. In this paper, the idea of employing objectorientation as a modelling technique for representing the behaviour of a process in terms of cooperative objects will be specified. The need to identify an abstract level, as an intermedi...

modular framework for robotic arm applications

A very large part of the business world today still uses traditional structured approach to the requirements gathering. On the technology side, extensive development has been-done in the area of Object-Oriented technologies that provides for productivity and quality through reusability, encourages team work and adopts a modular approach. Since the quality of the Object-Oriented applications has proven to be superior to the structured applications, especially in the area of maintenance, there has been a large demand for Object-Oriented applications. This leads to the situation where the requirements are structured, and the application needs lo be Object-Oriented. Subject Matter Experts (SMEs), with their knowledge of rhe system modeled, and analysts, with their knowledge of Object-Oriented paradigm, need to work together and re-organize the information fom the requirements analysis in the Object-Oriented fashion. This paper proposes and develops a methodology for the @an&ion. Emphasis is placed on preserving the knowledge captured in the requirements specification. The proposed methodology extends the existing Classes-Responsibilities-Collaborators (CRC) method and is tailored to be simple and understandable to SMEs, requiring minimal amount of