Modelling & Analysis

Question 1

What does the term ‘perspective’ mean?

Answer 1

A perspective relates to a software development role such as a manager, end-user or customer.

Question 2

What does the term ‘viewpoint’ mean?

Answer 2

A viewpoint relates to a set of particular characteristics of a model. Which reflects some specific aspect of software. Usually captured through some particular representation.

Question 3

What are the three different forms of representations?

Answer 3

• Textual
• Diagrammatical
• Mathematical

Question 4

What are representations?

Answer 4

Representation provide the abstract descriptions used in models. A representation usually reflects the concern of a particular viewpoint.

Question 5

What are the four main viewpoints.

Answer 5

• Constructional
• Behavioural
• Functional
• Data Modelling

Question 6

Describe the Constructional viewpoint, what modelling notations can be used for it?

Answer 6

Describes the static properties and constructional details.

Notations:
Structure Chart (call graph)
OO Class Diagrams

Question 7

Describe the Behavioural viewpoint, what modelling notations can be used for it?

Answer 7

Describe the causal links between events and system responses.

Notations:
State Transition Diagram
State Transition Table
State Chart
Message Sequencing Diagram

Question 8

Describe the Functional viewpoint, what modelling notations can be used for it?

Answer 8

Describes the actions and operations that are performed by the system.

Notations:
Dataflow Diagram
Activity Diagram
Pseudo Code

Question 9

Describe the Data Modelling viewpoint, what modelling notations can be used for it?

Answer 9

Describes the forms of data elements and the relationships between them.

Notations:
Entity-Relationship Diagram
OO Class Diagram

Question 10

Describe the Dataflow Diagram.

Answer 10

Circle - denotes operation.
Parallel bars - denotes data store.
Box - external source or sink of information.
Arrow - flow of information between components.

• Can be expanded to hierarchal form.

(Does not involve control flow involved in operations.)

Question 11

Describe the State Transition Diagram.

Answer 11

Box - state.
Arrow - transition.
Text above line - transition condition.
Text below line - transition action.

(No hierarchal form so doesn’t scale up well.)

Question 12

Describe the State Transition Table.

Answer 12

Tabular form of STD.

Useful for:

• Checking completeness.
• Developing the state model.

(Lacks ready visualisation of STD but scales better. Still not hierarchal.)

Question 13

Describe the Statechart.

Answer 13

Supports:
Clustering of states to form superstates.
Concurrency of states.

Question 14

Describe the Sequence Diagram.

Answer 14

• Vertical dimension represents time.

- Horizontal dimension represents interactions between objects.

Question 15

How do we analyse models?

Answer 15

Tabulation - can be used for checking completeness.

Walkthroughs & Scenarios - can be used for checking correctness.