The visualization window
incorporates the following elements.
This menu provides descriptions of the algorithm and of the DAJ toolkit.
- About Algorithm
- This is a descriptive text provided by the implementor
of the algorithm being visualized.
- About Toolkit
- This is a descriptive text about the DAJ toolkit itself.
- This establishes a Web connection to the DAJ home
page. If the program is executed as an applet within a Web
page, this page is displayed in a new window of the current browser.
Otherwise a browser determined by the implementor of the algorithm is invoked.
- This establishes a Web connection to the page containging the
DAJ copying conditions as explained above.
- This establishes a Web connection to this
page as explained above.
The panel to the right of the visualization window contains the following
- The program is executed until termination, deadlock, or
interruption by the user.
- The program is executed in slow motion which allows to follow
the state changes more easily.
- If the program is interrupted, pressing this button lets the
program advance by one state change.
- If the program is running, execution is temporarily
- Redraws the screen. It should not be necessary to use this
button unless the time subscript of a node extends the visual range of the
node (in this case, the subscript becomes illegible by successive updates).
- The program is brought back into the initial state.
- The visualization window is closed and the program terminates.
The figure in the left upper corner of the visualization area denotes the
global time of the network (about the number of state changes that a node
could have performed so far).
A network node is represented by a disc containing the node label
subscripted by the local time of the node (the number of state changes
performed so far). The color of the boundary of the node denotes the current
state of the node:
- the node is ready for execution.
- the node is blocked (waiting for a message on some channel).
- the node has terminated execution.
A node can be dragged to a different location by clicking on it and moving the
mouse while keeping the mouse button pressed.
A communication channel is represented as a bar between two nodes;
the receiver node is denoted by a bullet at the point where the channel
touches the node. The color of the boundary of the channel denotes the current
state of the channel:
- the channel is empty.
- the channel holds at least one message.
- the channel is empty and the receiver node waits for a message.
Moving the mouse pointer over a node or channel in the visualization area lets
a window pop-up:
- The window displays some text determined by the implementor of the
algorithm. Typically this text contains information about the internal state
of the node.
- The window displays the messages contained in the channel in
the order in which they where sent (the oldest message to the top of the
window). Each message is represented by a line of text determined by the
implementor of the algorithm
If multiple channels overlap, move the mouse pointer to the bullet
representing the receiver side of the channel to be selected (this selection
takes priority over the other channels).
Due to problems with Java AWT (Abstract Window Toolkit), the pop-up
windows may have abnormal appearance if the program is executed as an applet
in a Web page.
The foot contains a text line that gives further information about the
last state change respectively about the last action performed.
Maintained by: Wolfgang Schreiner
Last Modification: November 14, 1997