Analysts use various tools to understand and describe the information system. One of the ways is using structured analysis. Structured Analysis is a development method that allows the analyst to understand the system and its activities in a logical way.
It is a systematic approach, which uses graphical tools that analyze and refine the objectives of an existing system and develop a new system specification which can be easily understandable by user.
It is logical rather than physical i. During Structured Analysis, various tools and techniques are used for system development. It is a technique developed by Larry Constantine to express the requirements of system in a graphical form.
It shows the flow of data between various functions of system and specifies how the current system is implemented. It is an initial stage of design phase that functionally divides the requirement specifications down to the lowest level of detail.
Systems Analysis & Design - Ch 2 - Development Methodologies
Its graphical nature makes it a good communication tool between user and analyst or analyst and system designer. It gives an overview of what data a system processes, what transformations are performed, what data are stored, what results are produced and where they flow.
DFD is easy to understand and quite effective when the required design is not clear and the user wants a notational language for communication.
However, it requires a large number of iterations for obtaining the most accurate and complete solution. A context diagram helps in understanding the entire system by one DFD which gives the overview of a system.
It starts with mentioning major processes with little details and then goes onto giving more details of the processes with the top-down approach. A data dictionary is a structured repository of data elements in the system.
It stores the descriptions of all DFD data elements that is, details and definitions of data flows, data stores, data stored in data stores, and the processes.
A data dictionary improves the communication between the analyst and the user. It plays an important role in building a database.
Most DBMSs have a data dictionary as a standard feature. Decision trees are a method for defining complex relationships by describing decisions and avoiding the problems in communication. A decision tree is a diagram that shows alternative actions and conditions within horizontal tree framework. Thus, it depicts which conditions to consider first, second, and so on.
Decision trees depict the relationship of each condition and their permissible actions.
A square node indicates an action and a circle indicates a condition. It forces analysts to consider the sequence of decisions and identifies the actual decision that must be made. The major limitation of a decision tree is that it lacks information in its format to describe what other combinations of conditions you can take for testing.
It is a single representation of the relationships between conditions and actions.
Decision tables are a method of describing the complex logical relationship in a precise manner which is easily understandable. It is useful in situations where the resulting actions depend on the occurrence of one or several combinations of independent conditions.
The entries in decision table are given by Decision Rules which define the relationships between combinations of conditions and courses of action.
Structured Analysis Tools
In rules section,. Structure English is derived from structured programming language which gives more understandable and precise description of process.
It is based on procedural logic that uses construction and imperative sentences designed to perform operation for action. It is best used when sequences and loops in a program must be considered and the problem needs sequences of actions with decisions. It does not have strict syntax rule. It expresses all logic in terms of sequential decision structures and iterations.
What is Structured Analysis?
It may specify the physical programming logic without actual coding during and after the physical design. Use decision trees when sequencing of conditions is important and if there are few conditions to be tested.
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