Mouse moves are submitted to an AWS SQS Queue
Use the grey canvas on the left to draw a shape with the mouse while you hold down the left mouse button.
As you draw, messages will be sent to an SQS containing information about the X & Y coordinates of the mouse. These messages will be received by the browser polling the same SQS queue with 3 different subscribers, each rendering the events they receive on their own canvas.
Notice how the points are drawn out of order on the right-hand side and no single canvas has the complete drawing?
Points are drawn out of order because messages received via an SQS queue are received in an indeterminate order. This is a characteristic of the standard SQS queue. And since each canvas is polling the same SQS Queue, they are competing for the messages in the queue, and will arbitrarily receive the points events and render them, stealing them from the other canvases.