UML and Developmental Models

Question 1

What does UML ,UCD and DFD stand for?

Answer 1

• Unified Modelling Language
• Use Case Diagram
• Data Flow Diagram

Question 2

What is UML?

Answer 2

• an analysis tool which is used to illustrate / model computer applications

Question 3

What is a Use Case Diagram?

Answer 3

• a method of describing how a user interacts with a system

Question 4

What is an actors in a UCD?

Answer 4

• An actor is the term used to denote a role that is external to the system.
• The actor is often a person or organisation

Question 4

What is an actors in a UCD?

Answer 4

• An actor is the term used to denote a role that is external to the system.
• The actor is often a person or organisation

Question 5

What is a use case in a UCD?

Answer 5

• A use case is a representation of a function within the system.

Question 6

What is the system boundary?

Answer 6

• a system boundary is a rectangle that is draw around all of the use case symbols and represents the confines of the system.
• actors are outside the system boundary

Question 7

What is an association / communication in UCD?

Answer 7

Lines showing the link between a use case and actor(s). A use case can be carried out by many actors and an actor may carry out many use cases

Question 8

What is a <>

Answer 8

• Dotted lines with arrowheads and the text “<>” showing the links between use cases.
• Indicates that the functionality of a use case is used in another use case

Question 9

What is an <>

Answer 9

• dotted line with arrowheads and the text “<>” showing that the functionality of a use case contributes to the functionality of another use case
• conditional

Question 10

Steps in creating a UCD?

Answer 10

• identify actors
• draw system boundary
• identify use cases
• draw connections between use cases

Question 11

What is a DFD?

Answer 11

• DFDs provide a method by which the movement of data through a system can be visually represented

Question 12

What is an Entity?

Answer 12

• AN entity is a person, agent or company outside the organisation being examined that provides some data to the system or receives some information

Question 13

What is Data Flow?

Answer 13

• A data flow is represented by an arrow from one symbol to another and generally begins with a verb.

Question 14

What is a data store?

Answer 14

• A data store symbol represents a storage location within the organisation

Question 15

What is a process?

Answer 15

• A process symbols is used to describe any activity that transforms data and generally begins with a verb

Question 16

Name the primary DFD rules and conventions?

Answer 16

• Data cannot flow between:
  
  • Entity - Entity
  • Data Store - Data Store
  • Data store - entity
• Avoid black holes
  
  • data flow produces nothing
• Data that is discarded represented by data flow to nowhere

Question 17

What is a Level 0 DFD?

Answer 17

• also known as a context diagram

- shows entities and flow of information to and from the information system only

Question 18

What is a Level 1 DFD?

Answer 18

• Shows entities, data stores and flow of information within the high level processes of the information system

Question 19

When is a Level (n) DFD used?

Answer 19

• When a level 1 DFD is too complex and contains too many processes, create a whole new DFD for each process that describes how the process is accomplished
• Process is called DFD Levelling