MY BOOK REVIEW

OBJECT ORIENTED ANALYSIS and DESIGN

Book

Edward Yourdon and Carl Argila

Author

QA 76.64 Y68 1996

Reference no.

CHAPTER 3

The formulation of a problem is often more essential than its solution which maybe merely a matter of mathematical or experimental skill.

                                                                                                                -Einstein and Infeld

                                                                                             The evolution of physics (1938)

This is a true story, a small European country with a large European social system installed a new information system this system replace an existing legacy system which had become enormously expensive to maintain. The system was massive tracking and reporting on all of the various government benefits, pension program etc. the analysis who were responsive for the specification of the new system decided to use an object-oriented approach. Their analysis led them to identify the object with names like citizen, pension, beneficiary and various other “appropriate” object names.

It was not until sometimes after the deliver of the system that the failure of this object-oriented analysis became apparent. As explained by one of the system developers most of the maintenance change involved changes in so-called legislative rules. Nowhere, however was there a legislative rule object or anything similar the secrets of legislative rules were embedded throughout the system therefore, whenever one of these legislative rules changes, it usually required that the very significant system-wide change be made.

Object-oriented techniques hold the promise of very significant improving both the quality and productively of software development. However the benefits of the object-orientation can be reaped only if the right set of objects identified. An appropriate set of objects, for a given application domain assures reusability promote extensibility and helps to ensure the quality and the productivity improvements in herent in the object oriented paradigm. Without a formal method for establishing what are the objects, software developers risk simply hacking at the object level.

In this chapter a number of practical techniques to help find and keep good object. Much more of what is presented in this chapter is akin to a chaos. Effect for software that is identifying small things at the start of a process which can have a big impact in the future.

Finding the right object is difficult but crucial if the objects are to be reusable. The combination of linguistic information analysis and 3- view modeling provides a fairly straight-forward, repeatable process for finding an initial universe of application domain concepts. The OOA /OOP worksheet provides a mechanism for extracting an initial set of object from the universe of application domain concept.

Although there are already many researches on aspect-orientation software development from requirements to design and implementation, there is not a practical way for adapting aspects to current Object-Oriented System Analysis and Design (OOSA&D) process. This paper presents a means to model crosscutting concerns based on OOSA&D. The approach is based on use-case driven development. Aspects which present crosscutting concerns are identified from use-case diagram, and then aspect specification table is used to describe the aspects in detail. Particularly the presentation is independent of Aspect-Oriented Programming (AOP) languages and the implementation environment. The approach can help developers get clear system structure and facilitate system maintenance and upgrade. This approach is also illustrated by a case study of a Prison Scoring System (PSS). Object-oriented programming can trace its roots to the 1960s. As hardware and software became increasingly complex, researchers studied ways in which software quality could be maintained. Object-oriented programming was deployed in part as an attempt to address this problem by strongly emphasizing discrete units of programming logic and re-usability in software.

The Simula programming language was the first to introduce the concepts underlying object-oriented programming objects, classes, subclasses, virtual methods, coroutines, garbage collection, and discrete event simulation  as a superset of Algol. Simula was used for physical modeling, such as models to study and improve the movement of ships and their content through cargo ports smartalk was the first programming language to be called "object-oriented".

Object-oriented programming may be seen as a collection of cooperating objects, as opposed to a traditional view in which a program may be seen as a group of tasks to compute . In OOP, each object is capable of receiving messages, processing data, and sending messages to other objects.

Each object can be viewed as an independent little machine with a distinct role or responsibility. The actions or on operators the objects are closely associated with the object. For example, in OOP, the stractured data tend to carry their own operators around with them or at least "inherit" them from a similar object or "class. The traditional approach tends to view and consider data and behavior separately.