Creating Descriptions

The application is for writing use case descriptions with an aim of animating them to visualise the behaviour that would result from software implemented from that description. To create a description, the user should launch the application, choose the File menu and the New option:

The above dialog pops up and is for creating the elements of a new description:

A description is comprised of events, primary actors (responsible for triggering an event), precondition (state of event or primary actor before the event is triggered), post condition (state of event or primary actor after the event is triggered), secondary actor (an actor interacting with the primary actor during undertaking of an event), pre-state (state of secondary actor before interaction), post-state( state of secondary actor after interaction).  Some events might not have secondary actor.

Once elements of an event have been edited, clicking Confirm Event button registers that event on the description pane.

Consider a simple use case description involving two actors, Student and Lecturer. Let us suppose that the student is using a pen that the lecturer will need to use at some point. That is, the student gives pen to lecturer, and at some point the lecturer gives pen to student also. For student to give the lecturer a pen, the student must have pen, in other words, the student is at "has pen" state whereas the lecturer is at "no pen" state. We begin editing this description by capturing the actors. Clicking the Add Actors button enables the dialog where the actor can be written::

The added actors are also replicated for use as secondary actors. The two actors are now available to choose as primary actors:

 or as secondary actors:

The use can edit the preconditions (which are also replicated for use as postconditions). By clicking "Add Preconditions" button we get a dialog to add the two states "has pen" and "no pen":

After adding both states, it is possible to choose them either as states for the primary actor ( or event):

 or states of the secondary actor:

Suppose then that the first event is such that the Student gives pen to Lecturer and moves from has pen state to no pen state, and the Lecturer moves from no pen state to has pen state. Confirming this gives the following display:

The complete description becomes: