Chapter 5

Question 1

Name the two types of behaviour models

Answer 1

1. Control-flow oriented models:
   Captured with state charts and activity diagrams
2. Data-flow oriented models

Note:
State charts model the functional states of a component and the transition between them.

Question 2

State charts support the modelling of?

Answer 2

1. Hierarchical state charts and
2. Concurrent state charts

Question 3

Explain Activity charts

Answer 3

They model an algorithm by defining the control flow, using modelling elements such as operations, branches etc

They can be used to model the methods of a passive component that receives an input and produces an output. The behaviour of active components can better be modelled using state charts ( components that are continuously active)

Question 4

Activity chart with concurrent control flow

Answer 4

Fork modelling element is used to split the control flow into concurrent threads. The Join modelling element is used to synchronise the concurrent threads by combining them into a single common thread.

Question 5

In state charts, a transition consists of four elements, namely

Answer 5

1. The start and end state
2. The trigger
3. A guard
4. An effect

Question 6

In state charts, the trigger event types can be captured using 5 different event types in UML which are

Answer 6

1. Signal event
2. Change event
3. Call event
4. Time event
5. Completion event

Question 7

Hierarchical and concurrent state charts are modelled respectively by

Answer 7

OR-States which means that the component can either be in one state or another and AND-States which means that the component can be in one state and another state at the same time.

Question 8

Two modeling elements of block diagram are

Answer 8

Blocks and connections.

Question 9

In block diagrams, sources define

Answer 9

The entry point of data flow and only have output values.

Question 10

In block diagram, sinks define

Answer 10

The exit points of data flow and only have inport values.

Question 11

What is the difference between structure model and behavior model

Answer 11

Their difference lies in the aspect of the system that are to be modeled. Structure models focus on defining the structure of the system, the component’s internal behavior is not considered. They are at higher level of abstraction than behavior models.

The semantics of connections in data-flow oriented behavior models is often limited to mathematical relations.

Question 12

What is hybrid models?

Answer 12

It is a behavior model that contains both data-flow oriented and control-flow oriented models in a single model.

Question 13

The strength and weakness of control-flow oriented models

Answer 13

It’s strength lies in modeling state-based, discrete behavior and its weakness is modeling of continuous behavior.

Question 14

The strength and weakness of data-flow oriented behavior model

Answer 14

It’s strength lies in modeling of continuous behavior and it’s weakness in modeling control-flow and state-based behavior.

Question 15

Transition in state chart is defined by

Answer 15

1. Trigger
2. A guard
3. Effect

Question 16

Five trigger event types

Answer 16

1. Signal events
2. Change event
3. Call event
4. Time event
5. Completion event