Differences Between Structured Design and Object-Oriented Design

¶ … Structured Design and Object-Oriented Design

This report attempts to distinguish between two information technology design philosophies; namely, the basic differences between structured design and object-oriented design. The report also addresses the kinds of systems that are naturally more inclined to function with a hierarchy and those which function better through interacting objects. The report also goes on to discuss how systems were designed and when the methods used were most effective.

A structured approach was the original information technology design methodology and began in the early 1960's. Although industry insiders were very familiar with the concepts and processes, structured design gained a greater designation and popularity in 1979 when Larry Constantine and Edward Yourdon released a book on the topic known as the 'orange book' that was published by Prentice Hall. Many copycats followed and the structured design process became a standard. From that point forward, software engineers had a variety of approaches to structured design which entails that there is still a plethora of successful and viable structured design approaches.

Object-oriented design is most often known as a process for creating and coding an object-oriented application. But, similar to the term structured design, object-oriented design or OOD can also have variable meanings. Consider that OOD has been known as: a process for designing individual objects and methods for those objects, designing a hierarchy of objects or even the designing of vast libraries of reusable objects. Although object-oriented programming languages can be traced back to the mid-1960's, the actual term object-oriented was not actually coined until 1970.

With that being said, what actually are structured design and object oriented design? Structured design is a programming concept for the many program, process or system top down design techniques that are most often utilized by software engineers. "Structured analysis emphasized understanding the way the client conducted business, data flow diagrams, and "the flow of data." (Conner, 1980) By top down, we would mean the programming processing step refinement. Top down is a software design technique that attempts to describe program or process functionality through a big picture view that is then partitioned to smaller or more detailed levels one level at a time until the overall detail permits coding.

From a programming perspective, OOD is a design methodology where a system is modeled as a collection of cooperating objects or discrete items that could be either chosen or maneuvered like an onscreen graphic. It is not enough to merely identify and create objects, they must be thoroughly researched to note potential implications in an object oriented design which includes the many aspects of system components and their interactions and interrelationships. The design process takes these objects and bundles them into instances of classes or grouping of members that can be regarded as having similar attributes or traits. These classes are then categorized into class hierarchies. These hierarchies are based on class interrelationships where one class could be a specialization such as a subclass or derived class of another which could be considered its superclass or base class. The object-oriented design process is an important aspect of the object oriented programming stages because OOD helps clarify program, system or process implementation methods for all objects that must search through classes and superclasses.