user requirements
. natural language / diagrams to convey system’s functionalities and constraint
. high level ( conceptual doesn’t delve in technical aspects)
System requirements
how system is implement to meet user requirements
. provides a STRUCTURED DOCUMENT SET which contains a detailed description of systems functions, services and constraints
Functional requirements
Essentially what it does
- Statements of services the system should provide, how the
system should react to particular inputs and how the system
should behave in particular situations. - May state what the system should not do.
Non functional
Constraints …
Constraints on the services or functions offered by the system
such as timing constraints, constraints on the development
process, standards, etc.
* Often apply to the system as a whole rather than individual
features or services.
example of non functional
performance( time)
. useability
. security
why uml
natural language can be too imprecise ( can lead to misinterpretation) and code may be too detailed ( difficult to understand)
- UML is perfect medium
use cases
what can the actors do?
ARROWS POINT IN OPPOSITE DIRECTIONS IN INCLUDE AND EXTEND
- includes
include : base ————–>included - extends
extend : extended —————–> base
use case diagram ( include)
- includes
base ————-> included
. base also known as including
. When base is excecuted, included use case is always performed
. included use case can be executed on its own
eg :
includes
Place order ——————–> Add to cart
. Have to add to cart in order to place an order ( included always performed)
use case diagram ( extend)
- extends
extended —————> base
When base is executed , there is an option of performing the extended use case
- extends
eg : Apply discount —————> Place order
behavioural
use case diagram
state machine diagram
structure
class diagram
interaction
sequence diagram
