Chapter 7
CHAPTER 7: SYSTEMS ANALYSIS – ANALYZING REQUIREMENTS
1. Importance Of Analyzing Requirements
The design of the new system will be based on these determined requirements
2. Four symbols used in DFDs
Symbols | Description |
Circle | - Indicate some process or transformation of data. - Process show what a system does. |
Parallel Lines | - It used to indicate a data store. - Data store is where data are being stored until used by other parts or processes of the system. |
Rectangle | - Used to indicate external entity - An entity can be person, department, system or organization out of the system under consideration that supply data or receive data from that system. |
Arrow | - Indicate flow of data - Arrow direction pointing to a data store indicates writing or updating to the data store - An arrow coming out of the data store shows reading process |
3. Rules of Good DFD
· The word in the process symbol in the Context DFD is the name of the system
· Context DFD should possess one process symbol only
· Data store symbol should not appear in the Context DFD
· The first word in the process symbol in the intermediate and elementary DFDs must begin with a verb followed by a descriptive noun
· Process must be numbered
· Label clearly all data flows, entities, data stores and processes.
· The arrow direction for the data flows must be correct
· Crossing of lines will not be allowed in this course
4. DFDs Should Not Look Like Below
5. Characteristics of Good Diagrams
· It should be graphical with supporting textual detail
· It should allow the system to be viewed top-down, partitioned fashion
· It should have minimal redundancy
6. Technologies Assisting The Development Of Information Systems
i. Computer Aided Software Engineering (CASE) Technology
ii. Object Oriented Development Technology
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