state machines

Question 1

state

Answer 1

condition the object stays in

Question 2

trigger

Answer 2

the event that causes the transition

Question 3

guard

Answer 3

a conditional statement that must be true for an event to occur

Question 4

event

Answer 4

action that happens due to the transition

Question 5

transition

Answer 5

moving from one state to the other
may have a trigger guard and effect

Question 6

what are two other dynamic uml diagrams

Answer 6

activity diagram
sequence diagram

Question 7

activity diagram

Answer 7

a walk through from the user pov that models the flow of control

Question 8

sequence diagram

Answer 8

specify interactions within the system
time based approach showing which components are active and when
also shows when components communicate with each other and any bottlenecks

Question 9

what do state machines do

Answer 9

model the behaviour of a thing and specifies the state it goes through during its lifetime in response to an event

Question 10

what are some examples of the thing that state machines model the behaviour of

Answer 10

system/subsystem
instance of a class

Question 11

what is the state of a class

Answer 11

its attributes

Question 12

what are some benefits of state machines

Answer 12

model what happens when an object gets a message
include events that lead to object changing state
helps test and maintain systems
useful for systems with lots of dynamic behaviour e.g. control and communication systems

Question 13

what are the 3 event types

Answer 13

signal, call and time

Question 14

signal event

Answer 14

real time receipt of a signal

Question 15

call event

Answer 15

operation call

Question 16

time event

Answer 16

time based transition
e.g. a specific time or a time interval

Question 17

composite states

Answer 17

nested state that adds a substate
can be a single state at one level but can be viewed in higher detail
has its own start and stop

Question 18

concurrent states

Answer 18

states running in parallel using a fork and join

Question 19

what are the steps in building a state diagram

Answer 19

id the object and event that affect it
id possible states including the start and stop
check if events are conditional
id actions object perform in response to an even t
begin the diagram from the start state
build the diagram systematically via events and states
check for super or composite states