In XenApp and XenDesktop, Thinwire is a display remoting technology that uses screen decomposition, moving image detection and advanced caching techniques to offer an end user experience that is similar to or better than that of a local PC. Thinwire is optimized for minimum bandwidth usage, maximum server scalability and meets most general business use cases. Because of this balance, Citrix has selected Thinwire as the default display remoting technology.
Thinwire includes the following features:
For Visual Quality settings "Low", "Medium" (default) and "High", the transient detector dynamically evaluates screen updates to decide whether highly-animated areas should be sent at lower quality, in accordance with the Adaptive Display policy, to improve client performance and reduce bandwidth usage.
For the Build to lossless visual quality, Thinwire Compatibility Mode uses a "fuzzy-first" approach for large screen updates. This setting is targeted at 3D Pro users who are manipulating 3D models or other graphic-intensive applications. If the activity continues, a transient mode is assumed and the affected area is sharpened and cached once transient activity stops. For the initial large change, some lightweight image analysis is performed on the change area to determine whether to use "fuzzy transient" or "sharp transient" (lossless) - for example, when rotating a wireframe. It is more efficient, for FPS (Frames Per Second) and bandwidth, to encode simple imagery using the Citrix lossless codec and no loss in quality occurs.
The sharpen-to-lossless step in Build to lossless is also different. Rather than sharpening the affected area in one step, the area is sharpened in pre-determined blocks to help maintain interactivity and a smooth user experience. Sharpening a large change area mid-transient, for example moving a 3D model which is stopped briefly, then moved again, would previously cause a "stall", especially over a low bandwidth line. The size of the sharpening blocks depends on how far the quality was reduced to try and maintain the target minimum frame rate, which is an Adaptive Display policy setting. If the quality was significantly reduced, the sharpening block size will be smaller, with a minimum size of 128 x 128 pixels. If the quality was not reduced, for example, when the client has adequate processing power and bandwidth, the sharpening block size can be a maximum size of 384 x 384 pixels.