Description of the illustration adque040.gif

Applications at the top and bottom of the illustration are linked by arrows with three unlabeled queues in the middle. At top left Application A, Producer is linked with the leftmost queue by a downward-pointing arrow labeled Enqueue (Message 1). At bottom left, Application B, Consumer and Producer is linked to the leftmost queue with a downward-pointing arrow labeled Dequeue (Message 1) and to the middle queue with an upward-pointing arrow labeled Enqueue (Message 2). At top right, Application C, Producer and Consumer is linked to the middle queue by an upward-pointing arrow labeled Dequeue (Message 2) and to the rightmost queue with a downward-pointing arrow labeled Enqueue (Message 3). At bottom right, Application D, Consumer is linked to the rightmost queue with a downward-pointing arrow labeled Dequeue (Message 3).