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Table of contents

1Example

Checking UML Sequence Diagrams

Table of contents

1Example

With Model Expert you can validate UML Sequence diagrams to check for some common errors:

  • Lifelines not being instances of EA types
  • Messages between lifelines not calling methods of the target

Note: Sequence diagrams are checked against a fixed set of rules, and do not use a reference model.

Example

Step Description See Also
Find the package ‘Example 2 – Sequence diagrams’, and open the ‘Components’ diagram:

These are some simple components, with some simple operations.
Find the sequence diagram ‘Diagram #1’.

Note that Component 3 is not an instance of the component, it’s the component element itself – a deliberate mistake. If you switch on the diagram setting ‘Show Namespace’ then EA makes it more obvious that you’ve made a mistake..)
Now create some messages between the components
  • from :Component1 to :Component2, create a message, and in the Message drop-down in the message Properties, choose a operation from :Component2, such as Op A():

 This is the best way to avoid mistakes, but it only works if you know the EA trick of choosing valid operations from the drop-down. But EA will let you make a message using anything:
Now create another message, but this time just type in a new name for the message:

 

 This message doesn’t exist as an operation on the target component, so is probably an error.

The resulting sequence diagram now has two errors:

  1. there is a lifeline which is not an instance of something
  2. there is a message which has no implementation in the target element
Right-click on the diagram, and choose Specialize/Model Expert/Check sequence diagram This produces a list of the errors in the diagram:

…and will add colors to the diagram, to show where the errors are:
You can now see where to correct the errors in the diagram, using standard EA functions.