Using object-oriented analysis and design over traditional structured analysis and design

International Journal of Business Research, March, 2008 by Kenneth Pefkaros

ABSTRACT

The existing methodology used primarily in industry today in building computer-based applications is known as structured analysis and design. This methodology came into existence as a result of the structured programming techniques introduced in the 1970's. This structured systems development methodology (SDM) has been fine-tuned and used for many years in the real world. However, during the last several years object-oriented languages have become increasingly more popular and more widely used in industrial organizations as well as university institutions. As this trend continued a methodology was developed to assist the programmer with the development of applications using object-oriented languages. This methodology has become known as object-oriented analysis and design (OOAD).The OOAD strategy approaches the problem from an object perspective as opposed to a functional perspective, which is the primary focus of the traditional structured development methodology. During the last few years the increasing use of OOAD over the traditional structured development methodology has spread significantly. As newer and more sophisticated object-oriented languages are created, there appears to be an even greater need for an object-oriented approach to develop business applications. However, does this need warrant greater use of this new methodology over the traditional one? We will compare the two methodologies and their advantages and disadvantages in order to address this problem.

Keywords: Systems Analysis and Design, Object-Oriented Analysis and Design, Waterfall Model, Systems Development Life Cycle, Object-Oriented Life Cycle, Class Diagrams, Data Flow Diagrams.

1. INTRODUCTION

After surveying many articles as well as the current and popular textbooks on Systems Analysis and Design which include but are not limited to those mentioned in the references (Rumbaugh, Blaha, Premerlani, Eddy and Lorensen, 1991; Embley, Kurtz and Woodfield, 1992; Gibson and Hughes, 1994, Norman, 1996; Dewitz, 1996; Bahrami, 1999; Dennis, Wixom and Tegarden, 2002; Brown, 2002; Satzinger, Jackson and Burd, 2005; Booch, 2007; Hoffer, George and Valacich, 2008;), the author has observed much discussion on the use of object-oriented analysis and design over the traditional structured systems analysis and design. While the use of OOAD methodology is justified in many cases, in some cases it may be inappropriate and we should consider the use of the traditional structured analysis methodology in the design and development of information systems. This paper attempts to clarify the use of these methodologies, to compare the advantages and disadvantages of each and to make recommendations.

2. BACKGROUND

A methodology is a procedure for resolving the problems of the current system or for building a new one. There are many methodologies for the design and development of information systems which include: Systems Development Life Cycle (SDLC), Rapid Application Development (RAD), Object-Oriented Analysis and Design, Prototyping and many others (Dennis, Wixom, Teagarden, 2002). The SDLC is more commonly known as Structured Systems Analysis & Design. Structured methodologies allow the analyst to break down complicated systems into smaller, clearly defined and more manageable parts. The structured systems development life cycle is a step by step approach that moves from one phase to another commonly known as the waterfall model because the development is always moving forward with no mechanism in place to go backward. In this model the systems development phases-analysis, design, and implementation are executed sequentially with some repetition between the phases, where the activities in each successive phase start with the completion of the activities in the prior phase.

The first object-oriented languages came into existence during the 1960's and 1970's with Simula and Smalltalk. However, it was not until several years later that the Object-Oriented Analysis and Design (OOAD) methodology came into being (Larman, 2004). First in 1982 Object-Oriented Design emerged as independent topic (G. Booch, 1982), and later in 1988 Object-Oriented Analysis was introduced by S. Shlaer and S. Mellor (1988) and S. Bailin (1988). Many different object-oriented analysis and design methods evolved since then by such well known individuals as J. Rumbaugh (1991), P. Coad and E. Yourdon (1991) and many others.

The OOAD methodology uses an object-oriented perspective rather than a functional perspective as in the SSAD methodology. An object is a person, place or thing initially drawn from the problem domain which has three aspects to it: what it knows (its identity and certain attributes), who it knows (relationships to other objects) and what it does (its methods it is responsible for performing on its data) (Norman, 1996). Object-oriented analysis is the process of developing an object-oriented model of the problem domain where the initial objects represent the entities and methods related to the problem that needs to be resolved. Object-oriented design is the process of developing an object-oriented model of the system necessary to meet the specified requirements. So in this methodology we think in terms of things (objects) rather than functions.