DAJ Help

The visualization window incorporates the following elements.

Help

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.

Home

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.

Copying

This establishes a Web connection to the page containging the DAJ copying conditions as explained above.

Help

This establishes a Web connection to this page as explained above.

Buttons

The panel to the right of the visualization window contains the following buttons:

Run

The program is executed until termination, deadlock, or interruption by the user.

Walk

The program is executed in slow motion which allows to follow the state changes more easily.

Step

If the program is interrupted, pressing this button lets the program advance by one state change.

Interrupt

If the program is running, execution is temporarily suspended.

Redraw

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).

Reset

The program is brought back into the initial state.

Quit

The visualization window is closed and the program terminates.

Visualization Area

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:

Green

the node is ready for execution.

Red

the node is blocked (waiting for a message on some channel).

Blue

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:

Gray

the channel is empty.

Green

the channel holds at least one message.

Red

the channel is empty and the receiver node waits for a message.

Pop Up Windows

Moving the mouse pointer over a node or channel in the visualization area lets a window pop-up:

Node

The window displays some text determined by the implementor of the algorithm. Typically this text contains information about the internal state of the node.

Channel

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.

Foot Line

The foot contains a text line that gives further information about the last state change respectively about the last action performed.