NOODLE + + : a 3 - dimensional Net - based Object - Oriented Development Model

Object-oriented analysis and design methodologies are considered as the most popular software development methods for the 1990s. A common drawback, however, is that they have been developed informally. There is no theoretical framework enabling us to define precisely the object-oriented concepts involved, to solve concurrency problems, and to verify the correctness of the implementation. We propose a 3-dimensional net structure behind object-oriented software development. This structure consolidates the concepts of classes, inheritance, overloading and message passing through a single model. Inheritance and overloading can be unified with message passing in a 3-dimensional representation, but are physically differentiable by occupying the vertical and horizontal planes, respectively, of the model. Furthermore, the formal model can be mapped to various object-oriented analysis and design notations. The theoretical framework can thus be adopted for systems validation and verification for existing methodologies. The liveness and consistencies of objects can be verified, and inheritance and interaction coupling can be identified and checked. 1 Introduction Object-oriented analysis and design methodologies [1, 2, 3, 4, 5, 6] are considered as the most popular software development methods for the 1990s. Their main selling point is a user-friendly front-end graphical interface. A common drawback, however, is that they have been developed informally. The target systems cannot be defined precisely and implementations cannot be validated and verified in the absence of a supporting formal framework. On the other hand, a number of formal object-oriented specification languages [7, 8, 9, 10, 11] have been developed, independently of the popular methodologies. Practitioners are, however, rather reluctant to use these formal tools since unfamiliar languages are involved [12, 13]. To bridge the gap between object-oriented graphical notations and formal languages, we propose a 3-dimensional net-based object-oriented development model (NOODLE++). 2 We provide formal syntax and semantics to informal object-oriented concepts such as classes, inheritance, overloading and message passing. Our model has both graphical and algebraic representations which are semantically equivalent. The graphical representation can be used for visualization. Furthermore, unlike conventional diagrams, the graphical representation of NOODLE++ is 3-dimensional. This provides an additional degree of freedom towards integrating different aspects of a target system, but allows software engineers to project complex graphics into 2-dimensional views for the ease of understanding. Our model can be mapped to popular object-oriented methodologies such as object-oriented analysis (OOA) and object-oriented design (OOD) of Coad and Yourdon [2, 3]. Thus software engineers can still manipulate their designs using a …