Methods and Modelling

Methods and Modelling

Object-oriented methods and the unified

modeling language

Object-oriented concepts are crucial in software analysis and design because they address fundamental issues of software modifiability, adaptation, and evolution. Object-oriented methods are based on the concepts of information hiding, classes, and inheritance. Information hiding can lead to systems that are more self-contained and hence are more modifiable and maintainable. Inheritance provides an approach for adapting a class in a systematic way. With the proliferation of notations and methods for the object-oriented analysis and design of software applications, the Unified Modeling Language (UML) was developed to provide a standardized graphical language and notation for describing object-oriented models (Olimpiew & Homaa 2009). However, because UML is methodology-independent, it needs to be used together with an object-oriented analysis and design method. Because the UML is now the standardized graphical language and notation for describing object-oriented models, this book uses the UML notation throughout. Modern object-oriented analysis and design methods are model-based and use a combination of use case modeling, static modeling, state machine modeling, and object interaction modeling. Almost all modern object-oriented methods use the UML notation for describing software requirements, analysis, and design models (Malek et al 2009).

Software architectural design

A software architecture (Bass, Clements, and Kazman 2003; Shaw and Garlan 1996) separates the overall structure of the system, in terms of components and their interconnections, from the internal details of the individual components. The emphasis on components and their interconnections is sometimes referred to as programming-in-the-large, and the detailed design of individual components is referred to as programming-in-the-small. A software architecture can be described at different levels of detail. At a high level, it can describe the decomposition of the software system into subsystems. At a lower level, it can describe the decomposition of subsystems into modules or components. In each case, the emphasis is on the external view of the subsystem/ component that is, the interfaces it provides and requires and its interconnections with other subsystems/components (Friedenthal 2009).

The software quality attributes of a system should be considered when developing the software architecture. These attributes relate to how the architecture addresses important nonfunctional requirements, such as performance, security, and maintainability. The software architecture is sometimes referred to as a high-level design. A software architecture can be described from different views. It is important to ensure that the architecture fulfills the software requirements, both functional (what the software has to do) and nonfunctional (how well it should do it). It is also the starting point for the detailed design and implementation, when typically the development team becomes much larger (Espinoza et al 2009).

Software Design and Programming

The domain of software design and programming comprises distinct tasks, such as requirement analysis, software design, programming, testing, and debugging. It is the main goal of requirement analysis to specify the demands a new computer program or software system should meet. Ideally, future users of the computer system - or their representatives - should be involved in requirement analysis because they often have detailed knowledge about ...