1. Visual Formal Methods R J Walters

2. Introduction Motivation The Language The tools An example Conclusion

3. Issues in large systems Connecting the parts Getting the result to make sense

4. RDT Draw your processes (components) Draw how they are connected Run the model in the execution tool Use a model checker on it - SPIN * Limitations are accepted in exchange for ease of use

5. RDT: Processes Process has state Displayed as a picture Built using system of dialogue boxes 3 types of event –Receive –Send –Create

6. RDT: Events, Receive

7. RDT: Events, Send

8. RDT: Events, Create

9. An example process

11. RDT: Models Add instances of processes to your model Describe how these instances are (initially) connected

12. Models: Process Instances

13. Models: Connections

14. Example model

16. What next? Execute the model Use a model checker on it

17. Channels: Communication in RDT is founded on the pi-calculus Similar identity between values and channels RDT also permits asynchronous communication –Need channels in the execution tool

18. Executing the model Each Process instance has a window which shows: –Name and type –State –List of available actions –List of local channel names mapping these to instances of channels

19. Executing the model Each Channel (instance) has a window which shows: –Name –List of values held in the channel

20. The Execution tool

22. RDT: Conclusion Language, model construction tool, execution tool, translation tool Builds formal models using “informal” methods