Your first model

Open the simulator#

Go to starter.mysolvers.com. There is no sign-up and nothing to install. You land on an empty canvas with a toolbar down the left edge — across the top on a phone — and playback controls at the bottom.

Build the model#

1. Open the Queueing Systems button in the toolbar. It unfolds into the three components you can place: Generator, Queue and Server.
2. Pick Generator and click on the canvas to drop it. Do the same for a Queue to its right and a Server to the right of that. Double-click a component to rename it.
3. Choose the Create Connection tool — the arrow — and drag from the generator to the queue, then from the queue to the server. Entities will travel along those arrows.
4. Switch back to the Selection tool and click a component. A small toolbar appears above it with that component's settings, plus buttons to copy or delete it.

If something is left unconnected the simulator will not start: it highlights the offending component and explains what is missing. The wiring rules are short — a generator needs somewhere to send entities, a queue and a server each need a source.

Run it#

Press play at the bottom of the screen. The clock in the top right corner starts counting simulated time, and entities begin moving through the model.

Each component gains a row of chart toggles beneath it. Turn on the queue's length chart and the server's state chart first — between them they tell you almost everything about a simple model. The clock has its own toggles for whole-model statistics: the rate of completed and dropped entities, and a histogram of how long entities took to travel through the system end to end.

The speed control next to play runs the simulation from a quarter of real time up to sixteen times faster, so a long-running effect does not need a long wait. Restart replays the model from an empty state; stop returns you to editing.

Tune it while it runs#

Settings can be changed without stopping the simulation, which is the fastest way to build intuition for a system. With the model running, select the generator and raise its arrival rate above the server's service rate. Within seconds the queue fills, the server stops idling, and the generator starts recording rejected entities.

Then raise the queue's capacity and watch what changes — and what does not. A bigger buffer absorbs bursts and postpones rejections, but it cannot make a server faster than it is: the cycle time histogram simply stretches to the right. That trade-off between waiting and losing work is the heart of capacity planning, and it is visible here in a couple of clicks.

Save your work#

Your model is stored in the browser as you edit it and restored the next time you open the simulator, so closing the tab is safe. To keep a copy, or to move a model to another machine, use Save to file in the toolbar and Open file to bring it back. Models saved by an older version of the simulator still load, with a warning that they predate the current format.