Information Modelling

Question 1

Briefly describe information modelling: what is it? Why do we do it? When do we do it?

Answer 1

What:

• analysis activity to build up an information model of the business domain;
• it is a conceptual model of data types and attributes, as well as their relationships

Why:

• to identify the main business concepts and relationships,
• to help the developer understand the business domain
• allows specification of important business constraints

When:

• during initial requirements capture (conceptual model)
• when designing a database for application (data model)

Question 2

What kind of information should be captured for information modelling?

Answer 2

Business information: the core data upon which the business depends (often provides the business with its commercial edge)

Question 3

What different types of business information are there? (5)

Answer 3

• People
• Products
• Processes
• Attributes
• Relationships

Question 4

What is a dictionary of terms? How do we produce it?

Answer 4

Business domain unfamiliar to developer; set of terms used by customer in a technical sense to describe the business/

Developers enter terms into the dictionary
identify redundant, ambiguous or missing terms
end goal: each term refers uniquely to each concept

Question 5

What are the different term types in a dictionary? (5)

Answer 5

• Actor
• Object
• Event
• Relationship
• Attribute

Question 6

Briefly describe entity relationship model

Answer 6

• identify strucutred (non-atomic) concepts as entities, own attributes
• non-decomposible (atomic) data items are attributes
• establish relationships between entities

Question 7

What is included in the extended entity relationship model?

Answer 7

Generalisations; include subtypes and super types

Question 8

What is included in the UML version of the entity relationship model?

Answer 8

Aggregations (whole/parts)

Operations (methods)

Question 9

Describe what is meant by the attributes of a class

Answer 9

• data managed by the class
• included on a ‘need-to-know’ basis
• typically simple data types
• must be atomic
• typically take individual values in each instance of class - so values depend uniquely on the particular instance

Question 10

Describe what is meant by the services of a class

Answer 10

• business operations owned by a class
• direclty read/write class attributes
• written useing standard functional syntax

Question 11

What s the different between an attribute and an association?

Answer 11

Association:

• type has structure
• modelled in the business domain
• relationship name as one end role

Attribute:

• type has no structure
• not modelled in business domain