Structure of System Requirement

1) Process Modelling

- to show the process and function of the system and data flow among the processes. It also shows the data files used in the processes.

e.g. Data Flow Diagram & Structured Design

Data Flow Diagram

-System analysis and design tool that graphically show the flow of data in a system

- Used to show the process and function of the system

- Show the flow of data among the processes/entities

Example:

Ticket System

Structured Design

- Program design that uses graphical description tools (Structured chart). This approach involves breaking the programming into logical manageable portions of modules

Example:

Student Registration System

Benefits: Early detection of design flows, clear and complete documentation, modular design to break up problem into smaller sections and leads to better programs because modules are independent of one other

2) Conceptual Data Modelling

- shows entities relationship, system structure and relation among the data. e.g. Entity Relationship Diagram (ERD)

ERD

- A diagram that uses graphical concept to show the data flow from one entity to another entity by using types of relation and cardinality.

Chen Notation

An entity is an object or concept about which you want to store information. 

A weak entity is an entity that must defined by a foreign key relationship with another entity as it cannot be uniquely identified by its own attributes alone.

Actions, which are represented by diamond shapes, show how two entities share information in the database. In some cases, entities can be self-linked. For example, employees can supervise other employees.

Attributes, which are represented by ovals. A key attribute is the unique, distinguishing characteristic of the entity. For example, an employee's social security number might be the employee's key attribute.

A multivalued attribute can have more than one value. For example, an employee entity can have multiple skill values.

Connecting lines, solid lines that connect attributes to show the relationships of entities in the diagram.

Cardinality specifies how many instances of an entity relate to one instance of another entity. It is always linked to a relationship to connect one entity to another entity.

Source:

https://www.researchgate.net/publication/307110857/figure/fig3/AS:403359166156803@1473179727851/Entity-relationship-ER-diagram-of-Busan-traffic-data.png

UML Notation

Source: http://holowczak.com/wp-content/uploads/070617_1349_DrawingEnti1.png

3) Logical Modelling

- Shows what a system is or what it does and illustrates the logical part of a system and thus ignore the technical and implementation independent

- e.g. Pseudocode/Flow Chart/Decision Table

Pseudocode

- an informal high-level description of the operating principle of a computer program or other algorithm

Picture Source: https://www.google.com/url?sa=i&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FFlowchart&psig=AOvVaw2U5Kx9nlugcTgaYPigND7Z&ust=1586008498313000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCKiv0Ju0zOgCFQAAAAAdAAAAABAD

Flow Chart

- a diagram that shows a process, system or computer algorithm

For Flowchart Symbols: https://www.visual-paradigm.com/tutorials/flowchart-tutorial/

Decision Table

- Table that lists a variety of condition and the action that correspond to each condition

- System analyst can use decision table to show the detail process of new system consists of many condition or rules

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