This editor enables you to create or modify an Event Trace Diagram. Event Trace Diagrams illustrate different scenarios, which show the behavior of Objects in particular system states. There can be any number of Event Trace Diagrams in one OO model. The elements of an Event Trace Diagram are Objects, Messages and free text.
Objects and Messages can be assigned to Classes or to Operations. The name of the referenced Operation can be displayed as a Message label.
This diagram shows each Object as a vertical line and each Message as a horizontal arrow from the sender Object to the receiver Object. Time increases from top to bottom. Spacing is irrelevant but you can choose to group related Messages by placing them closer to one another. Only the sequence of Messages is shown, not their exact timing. Objects can send concurrent Messages. An Event Trace Diagram always starts in the top left of the drawing area and expands to the right and downwards.
Positioning Objects and Messages
Whenever you add an Object, all the Objects to the right of the mouse pointer are automatically moved to the right to make room. Whenever you add a Message, all the Messages in the diagram below the mouse pointer are automatically moved down. If you want to change the order of the Objects in the diagram, point the mouse at the Object that you want to move and drag it to its new position. All the other Objects are automatically moved as necessary to make room. Similarly you can drag a Message to a new vertical position. The other Messages are not automatically repositioned, enabling you to group Messages. If you want to move a group of objects, drag a selection frame around the objects and then drag them to the new position.
Pull-down menus
The following pull-down menus are available in the Event Trace Diagram Editor:
File
Edit
View
Options
The following popup menu is available on Objects:
Start Message
Alter
Delete
Edit
Edit Class
Edit Class Diagram
Annotations
Double-click on graphical objects
If you double-click on a graphical object this carries out the most commonly used command. The command started is different if you double-click on the label of an object or on the symbol excluding the label. For example, if you double-click on the name of an Object this carries out Alter on the Object name. If you double-click on the Object symbol outside the Object name this carries out Start Message.
The following table shows the full list of commands carried out when double-clicking on objects.
Symbol |
Label |
|
Object | Start Message | Alter |
Message | Edit | Edit |
Text | --- | Alter |