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Who?

A class model is usually created by the business or systems analyst.  Working alongside IT, the class model is used to communicate business requirements in a language IT can understand.

 

What?

A class model is the UML/object-oriented version of a data model. That is, it shows the data to be held within a system and the way the various data items are connected with each other. The concepts involved are similar to those in entity relationship models, but the UML notation has some additional features that enrich our understanding of the data.

 

A class model shows graphically the classes within a system and their relationships with one and other.  In a business system, a class model captures information about the particular things involved in the organisations operations, for example projects, customers and team members for a project control system.

 

How?

A comprehensive data model is necessary for the following reasons:

 

  • To determine the data requirements of the new/current business system.  What particular data does the system need to store?
  • It ensures a common understanding of all the data.  This is crucial if different systems/components are to be sharing data between one and other.
  • It is the basis of the technical implementation, with the class diagram being the initial plans.
  • It defines integrity rules about the data, with a structure of rules that reflect rules about the business.

 

Traditionally speaking a class can be anything about which information is to be stored about.  In reference to local councils, this could be customers, leisure events, council buildings etc.

 

A Class is represented by a rectangular container, which contains the name of the class in the top compartment.  Attributes are listed in the lower compartment, attributes relate to the things/pieces of data which we need to know about the class.

 

Classes are linked together by Associations, which will be in the form of a meaningful business phrase linking two classes, for example:

 

  • Customer MAKES booking
  • Customer SUBMITS booking

 

For the effective communication of the class diagram between business and IT, it is critical that the associations are named clearly to reflect the business rules they support.

 

 

Numbers at each end of the class association indicate the range of numbers of instances of classes allowed in the relationship.

 

Possible number ranges could be:

 

  • 0.. 1 (Zero to 1)
  • 0.. 10 (Zero to 10)
  • 0.. * (Zero to many/unspecified)
  • 1.. * (One to many/unspecified) etc.

 

 

So here with this example of a class association we see that the Customer (class) Submits (relationship) zero or one (multiplicity) Planning Applications (class).

 

Things to consider

Class models are particularly used at the requirements definition stage of analysis.  After completion, with a supporting requirements catalogue, these should be passed to IT to implement the changes.  Additionally, other system models such as use cases may be required  as well.

 

For more class model examples and templates, visit http://creately.com/diagram-community/popular/t/use-case

 

 

Return to Business Analysis Framework

Class Models

Kelly Hunkin

Senior Business Analyst

Tel: 01506 283885

 

Heather Adams

Business Analyst

Tel: 01506 282879

 

Email the Business Analysis team

 

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