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Chapter 2: SYSTEMS ANALYSIS

This chapter deals with techniques applied in information system analysis, data modeling and normalization. This chapter shows a process of providing full specification of systems to users to help them consider and accept. This specification is also a major information source for designers of the new system. It not only specifies the system's objectives but also describes the work and its constraints to which designers have to comply.

2.1 Analysis of structured system

This part discusses the process of system analysis, analysis methods and tools supporting the analysis of data collected in previous surveys.

2.1.1 Overview of system analysis

System analysis is a relatively young field in mankind's knowledge but demand for system analysis existed many centuries before the introduction of computers. In mid 19 century, practitioners in labor, organization and methodology had established many improved methods of working. This is the first approach to system analysis.

With the development of information technology, system analysis science also develops more and more vigorously and has a significant role in a life cycle of an IT application and of IT projects in general. At the moment, there is no method that ensures success and that can be viewed as a "right" way for analysis but the application of structured system analysis increases the chance of success for most of typical applications and it proves efficient in a range of analysis in real life.

Until today, system approach is still viewed as a sound foundation for structured system analysis.

Structural system analysis is a modern approach to different analysis and design phrases of the system development process which is accepted because of its strong points over other traditional approaches. The structural system analysis has the following main characteristics:

* The system is developed in the top - down order;

* During system analysis and design, several tools, techniques and models are used to record and analyze the current system and new requirements of users, and define a format for the future system;

* The major tools used in structural system analysis include: function diagram, data flow diagram, data dictionary, process specification, Entity-Relationship diagram;

* Separation between physical model ad logical model. A physical model is often used in surveying the current system and designing the new system while a logical model is used in analyzing system's requirements. This is a significant advantage brought about by the structural system analysis method;

* Acknowledging users' role in different steps of system development;

* Different steps in structural analysis and designing can be carried out at the same time rather than in one by one order. Each step can improve the analysis and designing made in a previous step;

* Structural analysis is supported by advanced technology in both hardware and software, therefore system development with this method is less complicated;

* Structural analysis when put together with the prototype method can help users and analysts have an idea of the new system and help make best use of both methods.

Two models of structural system analysis:

Waterfall model: has been a basis for a majority of structural system analysis methods since the 1970s. This model consists of different phases carried out one after the other. Each phase can be assigned to a group of experts.

Spiral model: initiated by Barry Boehm, has become more and more popular and a basis to iterative development systems. This approach also consists of various phases carried out one after the other as in the Waterfall model. However, the system development process is divided into different steps and smoothened after repetitive steps, the system becomes more perfect after each repetitive steps. In this model, system developer can hand system's functions over to users more frequently rather than giving them all the functions at the end of the development process.

2.1.2 Nature of analysis

Analysis is the focus of system developing and is the stage when system designers have to work at two levels of definition regarding the study of situational issues and possible solutions in terms of "what to do" and "how to do".

System analysis process in its most general form includes the following main step:

* Identify the operation of the existing system;

* Understand what the existing system is doing;

* Understand the need of the users;

* Decide on what the new system should be doing;

* Decide on how the new system will function.

In the process of system analysis, it is not always possible to study every aspect of each of the above steps and this is the time to pay attention to the following:

* If the method of working applied to participants of system development (users, analysts, designers, and programmers) is efficient?

* If the update of changes that happen in the process of system development is touched upon;

* Tool for analysis;

* If workload allocation is reasonable? (Users have to take part in 2 systems (old and new) at the same time);

* If documents are easy to understand to all participants?

2.1.3 Importance of analysis in system's life cycle

A system's analysis and development life cycle include the following tasks: survey, analysis, design, implementation, system testing and approving, installation and maintenance. Main subjects in the whole life cycle of the system are: users, mangers and technical experts including analysis, design and program specialist...)

The primary purpose of the analysis activity is to transform its two major inputs, users policy and system charter, into structured specification. This involves modeling the users' environment with functioning diagrams, data diagrams, entity-relationship diagrams and the other tools of the system analysis.

The quality of system analysis can have a big effect on speed of system designing, the programming and time for testing