Design And Implementation Of SSVD Protocol

With the increasing integration and development of computing devices andnetwork communication technology, traditional computing mode can no longer fullymeet the requirement of daily production. Thin-client Computing, as a representation ofNetwork Computing, had been widely used as it was first put forward last century.Nowadays, Cloud Computing rapidly gains recognition and favor from a number offields, which largely stimulates the development of Thin-client Computing, making itradiate new vigor.This thesis firstly studied internal mechanisms and principles of several thin-clientsystems, like X, NX, RDP, ICA, VNC, for a long period. With lots of experimentalresearches on how internal mechanisms of different thin-client systems influence theirperformance on several specific applications, this thesis has multiple influencing factorsconcluded. Then, analysis the shortcomings of VNC on security mechanism, screenupdates mechanism, and discussed improving methods of other researches, after adetailed description of VNC on its system architecture, encoding and screen updates. Byutilizing existing improving methods and internal mechanisms of other thin-clientsystems, a new framebuffer level thin-client protocol based on RFB is proposed, namelySimple and Security Virtual Desktop, or SSVD. This thesis mainly discussed the designand implementation of SSVD on its message type, message format, communicationlogic, authentication mechanism, message transmission mechanism, screen updatesmechanism, server-push mode, etc. Within the thesis multiple aspects of innovation andefforts is made.First, a more simple and safe mechanism is proposed compared to VNC, and it isnow applied in authentication and message transmission within SimpleV1.0, softwarebased SSVD protocol.Second, traditional client-pull mode is replaced and a new server-push mode isemployed to improve screen updates efficiency.Third, in the process of comparision tests for thin-client systems, a new benchmark,Qvdatais used to measure screen update efficiency of thin-client systems. Qvdatarefers to ratio of translated video data amount of WAN to that of LAN, and is called “VideoQuality Ratio” for short. The high the ratio, the more complete screen updates transfers,and the more efficiency screen updates, finally the better system performance.At the end of the thesis, comparison tests are made to test the performancedifferences before and after the improvement on RFB. The results show that, SimpleV isprior to TightVNC on response time and screen updates efficiency.