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Thursday, 06 Nov 2008, 10:26:39
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Simulator Browser friendly
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The simulator window is divided into four sections:

  • Enabled transitions part is in the upper left corner showing the transitions that the system can take from the given state. You can choose the transition to be taken in the step-by-step manual simulation mode. In the random run simulation mode the transitions are randomly chosen.

  • Watches part is right below Enabled transitions part. Here you can observe the values of clocks, variables as well as task and processor utilization factors at any time during simulation.

  • The upper right part is displaying the Message Sequence Chart. Vertical lines correspond to the system process control flows showing their current states in rounded rectangles. Horizontal arrows are interprocess synchronizations performed via named channels.

  • The lower right part is a Gantt Chart showing the timeline where you can see the tasks being executed and a processor idle time.

Times Simulator
Enabled transitions
When simulating only one execution trace within the tree is explored. On every step of simulation there can be several enabled transitions, different ways to go, due to non-determinism. These possibilities are shown in the Enabled Transitions view.

Enabled transitions

The buttons below the list of enabled transitions are used to control the simulation process and navigate through the trace being explored. There are two modes of simulation: step-by-step simulation and random run initiated by means of control buttons and correspondingly.

Simulation in step-by-step mode is performed manually by selecting one of the enabled transitions and pressing the button to make the next simulation step.
Note: When selecting an enabled transition you can see the next predicted state of the system at the bottom of the Message Sequence Chart below the violet bar drawn with brighter colors.

In the random run mode transitions are chosen randomly and the simulator continuously performs one simulation step after another. You can stop the simulation at any time by pressing the button.

When you have got a trace you can move along it back and forth in the Message Sequence Chart using and buttons. Being at any point of the trace you can observe the state of the system together with the variable values. The button moves the simulator to the end of the trace that is exlored so far. It is possible to continue simulation from any point withing the explored trace. In this case the tail of this trace will be erased.

If you press the button the simulator will reset its state to initial as if you have just started it.

In this section you can observe values of variables and clocks as simulation goes. You can choose the view to see either only clocks, only variables or both together. There is also a fourth view with two progress bars in it. The first progress bar is showing the processor utilization, i.e. how busy is the processor executing your model tasks. This is an average value taken from the beginning of the current execution trace. The second bar is showing momentary task queue utilization, i.e. how many task instances are currently in the queue relative to the queue capacity (sum of Max # of tasks parameter for all tasks).

Processor and task queue utilization

Message Sequence Chart
Traces in Times are represented by Message Sequence Chart (MSC), a UML-like sequence diagram showing concurrent execution of processes and their intercommunication. The MSC view is quite interactive: you can observe the whole execution trace, move to particular states in it, hide/show different processes etc.

In the Message Sequence Chart process states are hidden (replaced by a thin vertical line) if they have the same names as the name of a state since the last state change. To view the state names of all processes at a certain level of the chart move over the pointer to this level.

See also:

Times Editor | Analysis

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