Cloud - Based Zero Client Display Scheme And Its Optimization

With quick development of cloud service these years, computer devices will meet a revolution in future. Enterprise users can easily handle data storage, sharing, and process by using cloud. But cloud service demand customer access it through a PC currently, could it happen that user can still access cloud without PC? E.g. a school’s computer room do not prepare PC for every students, while it let6to8students share one high-end server, or all students in the room share one cloud server; all employees in one building can share the service of company’s private cloud via a low-price terminal device.Let user access cloud without PC is a solution environment of this paper’s research field-"zero client terminal solution". Zero client is a device connected to server (Ethernet or USB bus) that composed of cheap&simple but resourceful SOC, each user need only one zero client terminal, which is monitors and keyboard/mice plugged in, that let him or her access cloud directly. Multiple users can access cloud server simultaneously by their own zero client terminal.This paper focuses on graphic output of zero client solution:how cloud server put GUI image data to terminal devices more efficiently, how client side devices cooperate with server side. The aim of this paper is to make the transaction low bandwidth occupy and high quality user experience, just like using a PC.The research hardware of this paper is a SOC based device connected to host server via USB bus, this device is just a "custom USB device" to host side, there is no inbox driver software can support it. This paper will construct aUSB2VGA device on this device. The technical is to build multiple virtual graphic interfaces (on Linux system, it is frame buffer node) on cloud side by means of kernel module and upper layer software, let the graphic operations received by each interface and drawn on its memory space.transfer each’s GUI data via USB bus to the client side after processed. Zero client uses a protocol defined algorithm decode the data and reconstruct the GUI to user.Bandwidth high efficient usage is really important because there are multiple users sharing one USB bus, which derives many technique and algorithm aimed to low the bandwidth usage, method like time slice rectangle merge, method of using PNG or SFALIC lossless image compression, method of hardware JPEG decoder function usage to low the bandwidth occupy from frame data when playing video, etc.