Design And Implementation Of KYLIN Terminal Service System

The Terminal Service was firstly presented by Microsoft since Windows NT 4.0. By now, it has been a standard service of Windows server. Terminal service can allow remote computers to run desktops and applications on a server as though it is running locally. On the client side, users operate server's desktop using a keyboard and mouse just like sitting in front of the server side. All the applications and data are running on the server, only the display of desktop session returned to client's screen.The KYLIN OS is a major software project of the 863 Program. It is an advanced server operating system which has an independent intellectual property right. The research of KYLIN terminal service can enrich its range of application as a server OS, send the desktop and applications based on KYLIN system to a large scope of desktops including platforms on which KYLIN cannot running. Therefore, it will have a widely application prospect and significant meaning.The desktop environment of KYLIN OS is based on X Window System. This paper studies the X Window System, introduces its basic conception, the principle of X protocol, the type of X message, outputting and inputting, character of the widget, and then does some researches on the X protocol extensions.Then we discuss the current situation of remote graphical terminal, introduces some popular remote display protocols, such as ICA, RDP, SLIM, RFB, researches their principle, and summarizes their advantage and disadvantage. In addition, this paper discusses the remote display manner, screen update strategy, pixel caching and compression mechanism, which provides a theoretical foundation for designing and implementing the KYLIN terminal service.At the last of this paper, we design the major functional modules of KYLIN terminal service system in detail. For outputting, define a virtual framebuffer for each X server in the server memory segment, numbers of sessions can work separately. For inputting, the server will need to handle two types of input events coming from clients -keyboard and pointer events. These events will be injected into the X Server using the XTEST extension. For screen update, we present a new strategy combined with La2y-Pull and Server-Notify method.