Protocol Enhancement and Compression for X-Based Application Sharing

Application sharing is a technology which allows two or more users located at geographically different places to synchronously work with an unmodified single-user application. To make this technology available to the network-based X Window System, several different software products have been developed. All of them use a protocol similar to the X Window System protocol X11 to display the output of a single-user application on more than one screen and to receive response from more than one user. However, this protocol was designed to be run over a fast LAN. Used over a high-latency or a low-bandwidth connection, it leads to serious delays and loss of interactivity. While there have been some efforts to make the X11 protocol more suitable for those scenarios, none of them have been integrated into application-sharing software. The objectives of this work are to review existing techniques for enhancement and compression of the X11 protocol, to prove that those techniques can be integrated into application sharing products by providing a prototype integration, and to identify areas of future work. It will be shown that the caching and compression techniques of the prototype integration reduce the synchronicity of application sharing products by up to 74%, and the amount of sent data by an average of 70%.

ICSI Technical Report TR-97-004

Technical Report