chapter 7

Question 1

What is the primary purpose of a UML sequence diagram?

Answer 1

• to model the dynamic interactions between objects during the execution of a single use case in a system.

Question 2

_______ Shows what messages (method calls) are sent between objects and when

Answer 2

sequence diagram

Question 3

Class diagrams were static, sequence diagrams are dynamic

Answer 3

t

Question 4

The 2nd most used diagram next to class diagram is ________

Answer 4

UML diagram

Question 5

CRC cards are to ________ while use cases are to _______

Answer 5

• class diagrams
• sequence diagrams

Question 6

what are the Key parts of a Sequence diagram?

Answer 6

*participant
*message
*axes

Question 7

_______ is an object or entity that acts in the diagram

Answer 7

participant

Question 8

_______ shows communication between
participant objects

Answer 8

message

Question 9

What do the axes in a sequence diagram represent?

Answer 9

– Horizontal: which object/participant
is acting

– Vertical: time (down = forward
in time)

Question 10

What is a sequence diagrams Purpose?

Answer 10

– See if our class diagram can satisfy each step of the use case

• Identify more classes that we may have missed in class diagram
• Identify methods of those classes

Question 11

how do we represent objects in a seq diagram?

Answer 11

in a rectangle
- <objectname> : <classname>
- Smith : Patient</classname></objectname>

• :<classname>. - anonymous object
  </classname>
  • :Patient
• <object>. - if class is unknown
  - Smith
  </object>

Question 12

how do we represent Messages / Method calls between objects?

Answer 12

• are indicated by arrow to other object
• Method(arg1, arg2 …)
  • Admit( patientID, roomType )

Question 13

explain types of arrow used in messages.

Answer 13

• message is indicated by arrow to other object
  – dashed arrow back indicates return
• d/t [ flat flow, procedure, async ]

Question 14

an object created after the start of the scenario appears lower than the others

Answer 14

t

Question 15

an X at bottom of object’s lifeline indicates ______

Answer 15

deletion

Question 16

How does Java delete objects?

Answer 16

Java doesn’t explicitly delete objects; they fall out of scope and are garbage-collected

Question 17

What is activation of method calls?

Answer 17

Thick box over object’s life line

• either that object is running its code
• or it is on the stack waiting for another object’s method to finish

Question 18

If one diagram is too large or refers to another we will indicate it with:

Answer 18

– an unfinished arrow and comment,
– or a “ref” frame that names the other diagram

Question 19

Why not just code Sequence diagrams?

Answer 19

– not all code is drawn on diagram
– sequence diagrams can be implemented in
many different languages
– non-coders can do sequence diagrams
– easier to do sequence diagrams as a team
– sequence diagrams provide more visual bandwidth

Question 20

What is a Control Object

Answer 20

• Represents an entity or manager that makes decisions
  (e.g. figures out what to do when a button is pressed)
• In simple systems, this is usually the application itself

Question 21

What are the relationships that Boundary, Entity, and Control elements must obey?

Answer 21

1. Actors can only talk to boundary objects.
2. Boundary objects can only talk to controllers and actors.
3. Entity objects can only talk to controllers and boundary objects.
4. Controllers can talk to boundary objects and entity objects, and to other controllers, but not to actors

Question 22

Which relationships are generally restricted or not permitted?

Answer 22

1. Actors can only talk to boundary
   objects. [ every thing else is not allowed]
2. Entity objects can communicate with an another Entity that it “owns” [ allowed with reservation ]
3. Boundary objects can talk to certain Entity objects and other Boundary objects it
   “owns” [ allowed with reservation ]
4. Controllers can talk to boundary objects and entity objects, and to other controllers, but not to actors

Question 23

______ Depicts data and behavior of a single object throughout its lifetime.

Answer 23

state diagram

Question 24

When to develop a state chart?

Answer 24

• To Model objects that have change state in interesting ways
  [ transactions, stateful sessions,
  controllers, complex UI ….]

Question 25

Its Not useful to do state diagrams for every class in the system

Answer 25

t

Question 26

________ is conceptual description of the data in the object

Answer 26

state

Question 27

______ is movement from one state to another, indicated by an arrow

Answer 27

transition

Question 28

What are substates?

Answer 28

If there are states share common transitions and internal activities You can make them substates