System developments can be done in several different ways, among these different approaches, two methodologies are especially important as they work as the fundamental system development approaches today. They are: traditional structured approach and object oriented Approach.
Traditional structured approach which was developed in 1970s became the dominant system development methodology in 1980s. However with the growing complexities of information system, the traditional approach has shown less competent in modern system development.
Since traditional structured approach has shown the inherit shortages when dealing with complex systems, which is the main trend of the current system. A new system developing method was introduced to better cope with the new system developing environment, that’s the object-oriented approach.
The following sections will provide a basic introduction of these two methodologies, compare their advantages and disadvantages. And finally a short discuss about the risks might involved in transition from traditional structured approach to object oriented approach
Structured system analysis & design approach:
Structured system analysis and design methods (SSADM) provide a framework of activities and tasks that need to be accomplished to develop an information system (Kenneth Pefkaros,2008). It contains structured analysis, structured design, and structured programming. SSADM is waterfall development, it break the whole life cycle of system development into four major phases: Analysis phase, Design phase, implementation phase and support phase. After one phase’s objective was fulfilled, it moves to the next one. Analysts and users proceed sequentially from one phase to another. Due to this working model, it’s not easy to move backward. The SSAD is based on the concept of functional decomposition(Kenneth Pefkaros,2008) the analyst breaks down the system into the basic processes to have an overall understanding of the project, then these basic processes are further divided into smaller ones so that the analyst have a full understanding of the project thus can take every essential element into consideration.
Advantages of SSADM:
AS SSADM follows the waterfall approach, each phase of the project can be clearly identified. So it’s easy for project management.
The concept of SSADM is straightforward, it’s easier to master for inexperienced analysts.
SSADM has been used in industry for a long time, it’s a mature technology and most company has employees trained well to use this approach.
Disadvantages of SSADM:
Critics have pointed out that the traditional structured approach has several drawbacks:
There are too many variations; no-one follows them correctly. Because the structured approach evolved over time, there are many variations. Some people still follow the original version of SSADM while others might pickup parts of the techniques without formally studies the details (John W. Satzinger, Robert B. Jackson, 2004).
SSADM is process-oriented, it ignores the non-functional requirements. So it’s hard for SSADM approach to address all the activities of analysis and design.
SSADM don’t run smoothly from end to end. SSADM use different notations to represent their results, making the transition from analysis to design difficult.
SSAD works in a waterfall model, so that requirements changes would greatly affect the whole project. Result in increase time and budget of the project development.
Object-oriented analysis approach:
As information system becomes more complex, a new analysis and design approach was introduced. Today object-oriented approach has gained huge popularities in both industrial field and academic field. The object-oriented approach views the system from an entire different aspect. It treats an information system as a collection of interacting objects that work together to accomplish tasks (John W. Satzinger, Robert B. Jackson, 2004). So analyst can break complex system into smaller, more manageable components. The primary difference between a traditional structured approach and an object-oriented approach is how a problem is decomposed. In traditional approaches, process and data are treated separately. It use one set of diagrams (Data flow diagram) to represent process and another separate diagrams (entity relationship diagram) to represent data, so traditional approach is either process-oriented or data-oriented(Dennis, Wixom & Roberta ,2006). The object oriented approach provides a balance between data and process. The system was decomposed into objects which contain both data and processes. Another difference between traditional approach and object-oriented approach is the development life cycle. Unlike SSADM works in a waterfall model, object-oriented approach works in an iterative way, so it’s easy to go back and make modifications. In OOAD there is no clear distinction between the analysis and design phases, which improves communication of user throughout the development life circle.
Advantages of object-oriented approach:
OOAD simplifies the development of the system. As OOAD breaks complex system into objects, so it can work on the components individually without considering a sequential process like SSAD.
OOAD’s Interactive objects model makes it easier to share among members of a development team as well as communicate with users. So OOAD involves more interactive between developers and users.
Object-oriented approach greatly improved the reusability of each system component. Because the modularizing development, the system is breaking into reusable package that can be plugged into other systems without starting from scratch in future (Dennis,2006).
Disadvantages of object-oriented approach:
In OOAD the initial designs for the system may be too simplified to be adequate (Kenneth Pefkaros,2008).
OOAD is overemphasis of this object methodology. In fact, another approach might be much better to use for the design and development of a system.
OOAD use different type of analysis from the traditional functional decomposition approach and structured programming methods. So for project development teams that have a long history of using the SSAD methodology, the transition to the OOAD will be difficult and consume lots of time and money (Hantos, 2005).
As mentioned above Reusability is one of the major benefits of object-oriented methodology. However It can also become a disadvantage. Without an explicit reuse procedure, many of the systems developed with this methodology do not lead to successful reuse on a large scale (Hantos, 2005).
Although theoretically object-oriented approach can address some weaknesses of SSADM, however when comes into real world project, there are more variables to consider, certain system development methodology are not necessarily associate with the success or failure of a project. Because most systems are not developed for technically succeed but for commercially succeed. So the transition from structured approach to object-oriented approach involves risks. This might include: the employee need training and practice to use the new technology productively. During this adapting period, the chances of making mistake increases. 2. The company might have huge investments on old methodologies. If the company use Object-oriented approach over traditional approach, it means the company have to abandon past investments, that’s a great losses increases the risks. So whether a company should adapt the object-oriented approach should depends on each company’s particular situation (Bill C. Hardgrave, 1997).
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As a system analyst, choosing the appropriate development approach is the first thing need to be considered in developing a system. Although object-oriented approach shows better performance in majorities of large system development project, it’s always good to remember there is no one best approach in developing a system. Dennis (2006) has identified 6 aspects as the criteria for selecting an appropriate developing approach. 1. Clarity of user requirements. 2. Familiarity with technology. 3. System complexity. 4. System reliability. 5. Short time schedules. 6. Schedule visibility. So selecting a developing methodology is not only a technical issue but also involves things like, the specific project which is going to be developed, the company’s financial state, employees’ technical background and so on.
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