Q&T is a key component in the HDX Broadcast technology stack for optimizing the delivering application and desktop virtualization over a wide area network. It intelligently analyzes the queue of drawing commands and omits those that are not needed to provide an accurate, responsive display to the user. By optimizing what commands need to be sent, this saves bandwidth on the network, as well as processing time on the client.

Imagine this sequence of events. The application is rendering 4 frames per second. Each frame has a size of 100Kb.

Based on the frame rate, it will take 400Kb/s of bandwidth to deliver a local-like user experience. But if you only have 200Kb/s of bandwidth, this is what you would get:

The frame rate dropped to 2 frames per second since that’s all you can send with the available bandwidth. But the worst part is that your session lost its interactivity. Because the system is still sending all the frames the application is rendering.

With queuing and tossing, the system drops frames in between to maintain the interactivity the user expects. With 200Kb/s of bandwidth, this is what you get with queuing and tossing enabled:

You are still getting 2 frames per second but the timing of the frames is aligned with what the application is intending to do. Therefore it offers a much better user experience.

To better illustrate this feature, the following video shows the interactivity benefits of queuing and tossing when editing a PowerPoint slide on a limited bandwidth connection.

Join me and my friends on twitter – Juan Rivera, Derek Thorslund, XenApp Team, XenDesktop Team