ISAD
is the systematic process of discovering, analyzing, documenting, validating and managing tbe needs and constraints of stakeholder for an information system
Requirement Engineering
Types of Requirements
Functional, Non Functional, Domain Requirements
What the system should do?
Functional Requirements
How the system should perform?
Non functional Requirements
Rules and Regulations
Domain Requirements
Requirements Engineering Process
Elicitation, Analysis, Specification, Validation, Management
Gather requirements
Requirement Elicitation
Resolve conflicts, refine and prioritization
Requirement Analysis
Document clearly Software Requirement Specification (SRS)
Requirement Specification
Confirm Accuracy
Requirement Validation
Handle changes
Requirement Management
Elicitation Techniques
Interview, survey, observation, document analysis, brainstorming, prototype
We validate
reviewing the srs with the stakeholders, creating prototypes, running walk through, checking for missing or conflicting items
it is a visual representation that shows
How data move in the system
What happens to that data
Where is the data stored
Data flow diagram
4 elements of DFD
Process, Data flows, Data stores, External Entities
the task or operations
symbol: a circle or rounded rectangle
Process
movement of the information
symbol: an arrow
Data Flows
where tge data is stored
symbol: rectangular shape with an open right side
Data stores
source, sink or terminator
symbol: rectangle
External Entities
Level of DFD
Level 0, Level 1, Level 2 and beyond
Context Diagram
Level 0
Data Flow diagram
Level 1
—> □
black hole
□ —>
miracle
—> □ —>
Grey hole