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Requirements Modeling -analysis methods where each method produces a set…
Requirements Modeling -analysis methods where each method produces a set of models(wht not how)
Purposes
Become the main driver of the Design phase
Show the system at different abstraction levels
Rules modeling
Any useful model is a good model
Strive for simple models
types
Object-Oriented Analysis(recent approach)Models the system in terms of objects and their interaction
Structured Analysis(long time), Models the system in terms of data objects and flow of data within the system
Behavioral model: State Transition Diagram (STD)
show how systems change state in response to events
State changes in response to events
Action to be taken as result of the event
System states
STD existed before UML:UML has its own variation of state transition diagrams, which it calls Statecharts, and are also called State Machine Diagrams, or State Diagrams.
Functional and Information-Flow models: Data Flow Diagram (DFD)
different btwn data and info
purposes
transformation applied on these objects (Functional model)
how data objects flow through the system (Information-flow model)
diagram
A bubble represents a process or a function that transforms data in some way.
Arrows represent the data objects, while a double line represents a data store.
A rectangle represents an external entity that either supplies the system with data, or information, or consumes data or information generated by the system.
multiple levels Information-flow Processing detail
DFD Level-2
DFD Level-0(context model”) entire system as a single bubble and the external entities
Process Specification (PSPEC): showing lower-level sub-processes and more information flow depending on the required abstraction level described in various ways, such as narrative language, pseudo code, or charts
Data model: Entity Relationship Diagram (ERD): specify the data objects consumed and produced by the system relationships between these data objects
2.Does not specify operations.
3.Has relationships with other data objects
reprewsent info that is produced/consumed by system
1.Has attributes(properties)
Control Flow Diagram (CFD)(cotrol flow not data(how eventt not data / activate , non-activates
Event (dashed line)
Input/output to/from Control Specification (CSPEC)(solid line_)
Input/output to/from Control Specification (CSPEC)
CSPEC describes how control in CFD is handled
How processes are activate/deactivated
CSPEC can be described using a STD
Process or function(bubbles)