Implementing Hierarchical Features in a Graphically Based Formal Modelling Language

1
Implementing Hierarchical Features in a
Graphically Based Formal Modelling Language

• Peter Henderson, Robert John Walters and Stephen
  Crouch
• Department of Electronics and Computer Science,
• University of Southampton,
• Southampton,
• UK.

2
Outline

• Visual Formal Models?
• The problem
• A solution (in RDT)
• Conclusion

3
Formal models

• An aid to building distributed systems
• Execution
• Rigorous analysis
• Appeal of visual interface

4
RDT

• Visual Modelling Language
• Processes
• Communication via channels
• Tools for
• Model Creation
• Execution
• Translation to Promela

5
What goes wrong

• Diagrams become cluttered
• Simple solution
• Hide low level details within processes
• RDT does this by showing only the name/type of
  processes and their channels in model diagrams
• But this is not the whole solution

6
The Problem

• What we would like to draw

7
The Problem

• What we would like to draw
• What we actually do

8
A process for the election algorithm
9
Using processes to build a model
10
Executing the model
11
Building the same model with connectors
12
The Connector in RDT
13
Issues

• Need to distinguish which end of a connector is
  which
• Dangling ends
• What if about channels in the process not in the
  connector?
• What about channels in the connector not known to
  the process?
• What about channels which connect at just one end?

14
Conclusion

• Visual Formal Models can be useful
• Single level diagrams get cluttered
• Addressing this requires attention to channels as
  well as processes, but it can be done

15
(No Transcript)