The Opportunity Costs of Systems Analysis and Design
Date: 24 March, 2010
For a specific application, the first task is to decide which methodology is appropriate for its development. The structured system analysis and design (SSAD) method has been fine-tuned and used for many years in the real world. However, during the last several years, object-oriented approaches towards analysis and design (OOAD) have become increasingly more popular and more widely used in industrial organizations all around the world. The OOAD strategy approaches the problem from an object point of view as opposed to a functional perspective, which is the primary focus of the traditional structured ...view middle of the document...
In this model, the systems development phases of 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 (Pefkaros, 2008).
The SSAD method is based on the concept of functional decomposition where the analyst breaks the system down into the basic processes that it comprises of and then breaks these down further into smaller parts and so on until the analyst understands all the essential components of the system being investigated (Senn, 1989). The analyst is required to meet with the user regularly to resolve problems and validate the user's needs based on the feasibility study conducted (Bowman 2004, p23). The system is considered in its entirety where the analyst first tries to understand the key features of the system, ignoring the smaller details until later. Next, the scope of system is defined where the physical details of the existing system are analysed. The analyst focuses on two objectives: what the new system should do and how it should do it.
With this methodology, the two primary concerns in developing an information system are processes and data, which are modelled independently. The processes are modelled by the data flow diagrams which illustrate the flow of data between processes and data stores and how it is altered as it moves through the system from source to destination. Data models are defined by entity-relationship diagrams (ERD's) which describe the data (entities) and the various associations among them (Pefkaros, 2008).
This principle of independently modelling the data and processes continues throughout the design phase. Based on the requirements provided by the user, a conceptual database model is defined and the database is developed, normalized and populated with data during implementation. From the structure charts and program logic the program modules are then developed and finally, to validate that the system meets the user's requirements, goals and objectives, the system is subjected to various levels of testing (Pefkaros, 2008).
On the other hand, we have the object-oriented method of analysis and design, which is based on principles including abstraction, encapsulation, modularity, hierarchy, concurrency, and persistence, and follows a repetitive and step by step approach to systems development. The major focus of the object model is object decomposition, where a complex system is decomposed into several objects (Rob, 2004).
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...