Object-Oriented Approach and Its Benefits

Abstraction, along with encapsulation, is a technique that hides the internal structure and implementation details of an object or some other software unit with its external interfaces. In this chapter, I focus on objects. Other software units include components, subsystems, and services. They will be discussed in subsequent chapters. Abstraction is about what a software module looks like to the outside world. Encapsulation uses these looks to hide the module s implementation details. At first glance, abstraction may not sound like a big deal. Quite the opposite, a system with well-designed abstractions greatly reduces couplings between its building blocks and is much easier to understand, maintain, and extend. Because highly coupled software systems 

Developing Chemical Information Systems An Object-Oriented Approach Using Enterprise Java, by Fan Li Copyright 2007 John Wiley Sons, Inc. 

To illustrate an object s interface versus its implementation, I would like to borrow a concept from an ancient Chinese philosophy of Taoism. Taoism believes that all objects in the universe are governed by two balancing forces—Yin and Yang. Yin represents the passive, introvert, and hidden aspects of an object. Yang represents the active, extrovert, and exposed aspects of an object. Therefore, we can consider an object s implementation detail that is hidden from the outside world as its Yin and its interface that is exposed to the outside world as its Yang. 

All object-oriented programming languages provide a feature called access modifier that facilitates separations between the interfaces and the implementations of an object. The way to achieve this result is to define member variables of the object as private or protected and define methods that provide services to the object s client as public. Only the public elements of an object can be accessed by its clients, and these are all that its clients care to know. In Java and C, we can go even further by creating interfaces that have only method signatures. The implementations of these methods are provided by the classes that implement these interfaces. Although there is no interface in C + +, you can, however, create an abstract class by declaring one or more of the class s methods as pure virtual. Abstract class is also supported by Java and C. Interfaces and abstract classes are useful software constructs for defining abstractions in a software system. 

Although the following example has been used by other authors in different contexts, I do not hesitate using it here again to demonstrate how to build systems with better abstractions. The reason is it uses the Java Collection Framework—a Java class library that is familiar to many developers and the framework itself is a good example of encapsulation. Suppose you want to design a compound library class that contains a list of individual compounds. Also suppose that the clients of the CompoundLibrary class need read-access to the compound list and the developer decides to use ArrayList to hold the compounds inside the CompoundLibrary class. A naive implementation of the CompoundLibrary class is as follows  

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When speaking of value, there is, basically, a financial and a non-financial interpretation of that term (Moller Tdrrdnen, 2003 323 Walter et aL, 2001 45). The financial meaning is closely linked to shareholder value, which characterizes a concept solely orienting a company s activities towards an enhancement of the value of its shareholders. As a result, the market value of the employed equity capital will be maximized (Buhner, 1992 418). The interests of other stakeholders are taken into account insofar as they are a means of achieving that objective. For the measurement of value enhancement, a set of diverse business metrics is developed, for example the economic value added (EVA), the discounted cash flow (DCF) or the cash flow return on investment (CFROI). However, the development of the shareholder value approach is not yet complete (Beck, 2003 3). Thus, many forms of application and transfer can be found, such as a combination of SCM and the shareholder value approach. Singhal Hendricks (2002, 2008) hint at the necessity of managing a supply chain in terms of the principles of shareholder value. The same thoughts can be found in the publications of Laupper (2004), Losbichler Rothbock (2006) and Neher (2003), who all deal with the transfer of the ideas of shareholder value into the context of supply chains. Due to the one-sided concentration on financial metrics and the value enhancement for the benefit of the company s shareholders, the stakeholder value approach is opposed to shareholder value (Achleitner, 1985 73 Bischoff 1994 ... 

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