What is the traditional approach to systems development?
A traditional/structured system development approach, as mentioned before, chiefly focuses on modeling the processes. Processes include capturing, storing, manipulating, and distributing of data as it flows through the system, [Laudon & Laudon 2006]. Therefore these methods detach data from the processes/functions. According to Laudon & Laudon, a different programming procedure must be written every time an action needs to be taken on a particular part of data, [2006]. According to Bordoloi & Lee, data flow diagrams and entity relationship diagrams are used in structured methods as tools for process modeling and data modeling respectively, [1994].
A common form of process model for structured methods is a data flow diagram which according to Valacich, George and Hoffer, is a common form of process model that shows a graphic that demonstrates the movement of data between external entities and the processes and data stores within a system, [2001]. A context level DFD describes the relationship between the system and the external entities whereas a lower level DFD describes the relationship between data stores and the processes that are carried out by the system. A lower level DFD explains process specifications using data dictionaries. Hoffer, Prescot and Mcfadden have described data dictionaries as repositories of information that document data elements of a database, [2005]. According to Laudon & Laudon, these data dictionaries not only contain information about individual parts of data and data groupings within the system but also define contents of data flow, [2006].
In structured analysis, process models like DFDs are converted in to structured charts which are top-down charts, showing all levels of process modules and the relationships between each of them, [Bordoloi & Lee 1994]. The data modeling is done by entity relationship diagrams which, normalized, can be translated in to relational database. Systems developed in such a way are normally referred to as traditional systems, [Bordoloi & Lee 1994].
What is the object-oriented approach to systems development?
In contrast, an object-oriented approach to systems development treats data and processes that work on that data, as “objects”. In other words, data and processes are encapsulated within an object, [Bordoloi & Lee, 1994]. In object-oriented approach, the procedures or processes are called methods, [Laudon & Laudon 2006]. Only methods associated with an object can access and modify the data encapsulated in the same object, [Laudon & Laudon 2006]. This is called the encapsulation. The information system is modeled as a collection of these objects and the relationships between them. Unlike structured approach, programs send a message for an object to perform an operation that is already embedded in it. Objects must collaborate between each other to make the system work, [Laudon & Laudon 2006].
In object-oriented analysis, there is a concept of class. As Hoffer, Prescot and McFadden describe, an object is an instance of a class that encapsulates data and process/methods, [2005]. According to Hoffer, Prescot and McFadden, a class is defined as an entity that has a definite role in the application domain about which the organization wishes to maintain state, behaviour and identity, [2005].
Bordoloi and lee are of the fact that in object-oriented development, the object model is built keeping in mind four basic elements, abstraction, encapsulation, modularity and hierarchy, [1994]. Abstraction occurs due to identification of similarities or common features between multiple classes or objects in the real world. This leads to generalization. Valacich, George & Hoffer have described that the classes which are generalized are called subclasses and the class they are generalized into is called a superclass, [2001]. Modularity refers to classes and objects packaged into modules in such way that makes their reuse convenient, [Bordoloi & Lee 1994]. According to Bordoloi and Lee, hierarchy can either be aggregation (a part of) or a generalization/specialization (a kind of) relationship, [1994]. When two classes have a kind of relationship, subclasses inherit the data and methods of their superclasses, and a subclass can augment or redefine the data and methods of its superclasses. This is explains the concept of inheritance, [Laudon & Laudon 2006].
In essence, object-oriented modeling starts with identification of objects and their classes in the problem domain, [Bordoloi & Lee 1994]. Object and class diagrams are made with class diagrams showing all the classes and their relationships and object diagrams showing all the objects and the messages that are being passed between them, [Bordoloi & Lee 1994]. The analysis stage changes in to design stage when low-level class objects are identifies with their attributes and methods. Similar objects are grouped into a class and classes are then grouped in to hierarchies in which subclasses inherit the attributes and methods of its superclass, [Laudont and Laudon 2006]. The implementation phase is carried out by converting the design into a program code using class library to identify re-usable design components, [Bordoloi & Lee 1994]. This leads to the creation of an object-oriented database, [Laudon & Laudon 2006].
Object-oriented systems can be viewed by using Unified Modeling Language which uses graphical diagrams. According to Booch, Rumbaugh & Jacobson, Unified Modeling Language or UML is a standard language for writing software blueprints. The UML may be used to visualize, specify, construct, and document the artifacts of a software intensive system. There are two principal types of diagrams are structural and behavioral diagrams, [Laudon & Laudon 2006]. Structural diagrams describe relationships between classes whereas object diagrams describe interactions in an object-oriented system, [Laudon & Laudon 2006].
What textbooks, journals and/or websites might be useful to search for articles about Comparing and contrasting the traditional and object-oriented approaches to systems development?
Bordoloi, B & Lee,M 1994, ‘AN OBJECT-ORIENTED VIEW Productivity Comparison with Structured Development’, Information Systems Management, Vol 11, No. 1, pp.22 – 30
Sinason, D.H & Normand, C.J 2006,’Omni Furniture Company: A Systems Development Life Cycle Case’, Journal of Information Systems, Vol.20, No. 2, pg. 81(ABI/INFORM Global)
Laudon, K & Laudon, J 2006, Managing information systems: Managing the digital firm, 9th Edn, Pearson education Inc.,Upper Saddle River, New Jersey.
Valacich, J. S., George, J.F., Hoffer, J.A. 2001, Essentials of Systems Analysis & design, 1st Edn, Prentice Hall, Upper Saddle River, New Jersey.
Shelly, G.B, Cashman, T.J.& Rosenblatt, H.J 1998, Systems Analysis and Design, 3rd Edn, Course Technology, 1 Main Street, Cambridge, MA 02142.
Hoffer, J A, Prescot, M B, McFadden, F R 2005, Modern Database Management. 7th Edn, Pearson Education Inc, Upper Saddle River, New Jersey.
Booch, G, Rumbaugh, J & Jacobson, I 1998, The Unified Modeling Language User Guide, 1st Edn, Addison Wesley, New York.
Nierstrasz, O 1989, Object-Oriented Concepts, Databases and Applications, 1st Edn, ACM Press and Addison-Wesley,.
Booch, G 2004, Object Oriented Analysis and Design with Applications, 3rd Edn, The Benjamin/Cummings Publ. Comp., Redwood City.
Whitten, J.L 2001, Systems analysis and design methods, 5th Edn, Galgotia Publications New Delhi.
