Modelling

  • Creating a Conceptual model of the app
  • Identifying the most essential items in the app
  • Review Analysis & Requirements
  • Show interactions
  • Focus on OO construction for the app
  • Should be quick
  • Only spend a few hours, at most!
  • Don’t worry about perfection / missing stuff

 

1 Identifying Objects / Classes

 

  • Pick out Nouns from Use Cases – candidate objects
  • Just make a list, don’t worry about missing any
  • Remove duplicates
  • Combine, where applicable
  • Might identify some attributes, which can be removed
  • Box the objects into a conceptual model

For example from an ecommerce system:

 

2 Identifying Class Relationships

  • Simply indicate associations with lines between boxes
  • Optionally add short note to describe the relationship
  • Can add multiplicity indicators
  • Doesn’t have to be perfect – this is a working / conceptual diagram
  • Conceptual object modelling

 

3 Identifying Class Responsibilities

  • Identifying the behaviour, which will eventually become methods
  • Review the use cases and identify the verbs / verb phrases
    • Identify who’s responsible
    • Remember that an object should always be responsible for itself

 

Verbs Actions
Verify items Display totals
Provide payment details Set payment details 

Set address details

Process sale Process order
Validate payment Validate payment
Confirm order Confirm order
Provide order number Get order number
Check order status Get status
Send order details email Create order confirmation email 

Send email

Beware of using SYSTEM with lots of behaviours!

 

Conceptual model should now start looking like class model

 

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