Control Flow Design Flashcards
What are the strong points of using use cases?
- Provide a good structtured description of what a system must achieve
- Good for specifiying actor interfaces
- Ideal for incrementally collecting requirements
- Good when initial requirements are poorly understood
What are the weak points of using use cases?
- Can only describe business functions; not higher or lower level things
- Cannot model hierarchical control strucutre of a software system
- Control logic is only implicit
What are the 2 main stlyes of modelling behaviour?
Flow-based model; actions chosen in a predetermined order
State-based model; actions triggered when in certain states
What are 2 Properties of guards?
Mutually exclusive
Exhaustive
What are the strong points of composing diagrams of subdiagrams?
- Can split complex control flows
- Each subdiagram has a logical entry/exit
- Can capture different levels of detail
What are the weak points of composing diagrams of subdiagrams?
- Can’t distinguish between exit wih success from exit with failure
- NEed to invent state variables to control what happens at higher levels
What are swim lanes used for in a UML activity diagram?
Show that different activities are done by different business departments
Can also show multithreaded processes executed on different hardware
What is the token passing model of a UML activity diagram?
- tokens created at initial node
- puhsed through graph
- routed at descisions, collected at merges
- replicated at forks, merged at joins
- consumed at final nodes