Module 8 - Sequence Diagram Part 2

Question 1

Constraint in sequence diagrams

1) all constraints appear in _________
2) all constraints constraint 1 and at most 2 event occurrences on lifelines
3) all constraints specify assertions that must be true for a execution to be valid

Answer 1

curly braces

Question 2

time constraints are anchored to a single event occurrence that points to the event occurrence that is being constraint.

This example shows the time constraint is anchored to the ___________________

Answer 2

message sent part of fireThruster()

Question 3

time constraint conveys a specific time or a window of time for a single ____occurance to occur … never multiple event occurrences .

Answer 3

event

Question 4

what does this time constraint “executionTime” mean ?

Note : the time constraint is placed in the sending portion of the Firetrhusters message

Answer 4

it is conveying that Firethruster message is sent at time = executionTime.

Question 5

what design decision is being conveyed with this time constraint ?

Answer 5

this conveys a window of time for that FireThruster message to be sent between 2am and 2:05 am GMT.

Question 6

a time constraint does not convey the idea of _______

Answer 6

waiting

. it does not wait for a time to occur like an accept event actions where a ________ arrivessignal event arrives.

Question 7

Duration constraint conveys the valid duration of time between a pair of _________ occurrences. the design is conveying that the firethruster message should execute anywhere 2min to 5 min long

Answer 7

event

Question 8

a state invarient specifies a bool condition that must be true the moment when the contrained event occurs in order for the ____ to be valid

Answer 8

trace

Question 9

the state invariant focuses on a single event occurrence being ___________

Answer 9

constrained.

current orbit radius = ordered orbit radius when true

Question 10

4 common kinds of combined fragments in a sequence diagram

1. opt - optional
2. alt - alternative
3. loop
4. par - parallel ( concurrency )

Answer 10

what do they have in common ?
1. they represent
2. they have a rectangle in a seq diagram
3. they have an interaction operator ( keyword like opt , par … )
4. they have at least one interaction operand
5. each interaction operand can optionally have a guard.

Question 11

what is a combined fragment in a seq diagram ?

Answer 11

a mechanism that allows you to add control logic to an interaction

Question 12

the opt ( optional ) combined fragment rep

Question 13

guard expression placement in the interaction operand

you should place the guard on top of the lifeline that has the first event occurrence on that lifeline.

Question 14

language law: opt can only have one region in the combined fragment
its all or nothing decision logic.

when does the guard expression get evaluation in an opt combined fragment ?

Answer 14

the last event occurrence get executed

Question 15

alt represents decisions logic with multiple outcomes. it must have multiple interaction operands to follow model law. The guard that is true represents which operation fires.

Answer 15

the moment the last event occurs right before the fc lifeline received the sensorStatus message in this case all the guards get evaluated

the guard that is true evaluates .

Question 16

remember reply messages are ___________ to show on the diagram but they count towards counting event occurrences in the test.

Answer 16

optional

Question 17

loop combined fraqment .. loop means number of occurances/ interaction.

language law - loop can only have 1 interaction operand . guards are optional design decision.

Question 18

loop(min,max)
loop(0, *) this conveys to the reader the min and max number of loops that the operand will perform. The loop will not end for an upper bound because its * .. it will only end if the guard is false.

loop(10) what does this design decision convey ?

Answer 18

exactly 10 interactions

its also legal to leave it as loop .. without any min or max values.

Question 19

loop(2,10) what does this information convey ?

the min number (2) is guaranteed to run two times. regardless of the guard expression . when the guard is true the it will run until 10 .

at least 2 and at most 10.

Question 20

how many times will the orbitRadiusUpdated message be sent in this loop ?

Answer 20

cannot be determined. it can be somewhere between 2-10 because of the guard .. but if the guard is removed how many times will the orbitRadiusUpdated message be sent?? 10 is the answer .

Question 21

how many times will the orbitRadiusUpdated message be sent in this loop ?

Answer 21

cannot be determined. it can be somewhere between 2-10 because of the guard .. but if the guard is removed how many times will the orbitRadiusUpdated message be sent?? 10 is the answer .

Question 22

par combined fragment represents concurrent sets of event occurances . a par must have ______ regions . the order of event occurances are non determinisitic . any order would be deemed valid .

Answer 22

multiple .

Question 23

the fc lifeline must send an initialize message _____ times before it can start receiving updates from any of the accelerometers . once all three are initialized the fc lifeline can recieve the updateYaw , updateRoll and updatePitch

Answer 23

3

Question 24

interaction use represents behavior _______ . it represents a use of another interaction in your model. it makes interactions reusable

Answer 24

decomposition

Question 24

interaction use is only allow to represent an

Answer 24

interaction

Question 25

___________are represented by stars on this diagram.

Answer 25

actual gates

Question 26

__________are represented by stars on this diagram.

Answer 26

formal gates