Research Of XML Document Access Method From The View Of Safety And Efficiency Based On Three-dimensional Coding

XML is a tag language exploited by W3C on Feb 1998. Because of the unique advantages, XML becomes the standard of data denotation and exchange in Net. Access control is a key factor impacting applied more as a result of builded in pen distributed environment. Therefore, it is important for us to develop access control mechanism to prevent XML data from unsafety access.It is necessary that controling single element and some elements having inference connection. But actually, XML access control mechanism did it hardly, and many access control mechanism is operose maintenancing control demands in a dynamic way. At the same time, much study is lack of considering efficiency for one user's request. Aiming at these shortages, this paper do two aspects works:One side, this paper studies the object in access control from the view of security. Analyzing the structure characteristic of XML, it finds that just restricting the single element access cann't answer the risk of XML structure. Therefor, this paper brings forward safety sensitivity information set. The set that including common-sensitivity set and inference-sensitivity set, defines the sensitivity set of endangering XML access safety.And accoding to the set's characteristics, a function expression to express the set was given.Based on these,a series of rules was advanced. It can help the system to realize a transform that changing from known sensitivity information set to a self-contained set. Through defining some methods, such as alternating-replace and disturb, the security can be protected very well. At one time, this paper gives a project of updating popedom flexibling.On the other side, this paper studies the popedom in the view of efficiency. Based on XML using an especial three-dimensional coding, we draw out the structure characteristic of the coding tree. Based on the memory structure of XML popedom rule, by dint of structure characteristic of coding tree based, the paper gives arithmetic of rewriting popedom rules and settles the problem of system responding efficinecy.Based on the results of theory study, the paper designs a structure of access control model and achieves the two important parts. Using some experiments, the paper tests the access control model. The resule of the test is more security and more efficinecy.