Translating From XML Schema To Relation Schema On Semantic Constraint

Extensible markup language XML technology has been widely supported in many domains and has had bright prospect of broad application since its appearance.The key role of XML lies in the data exchange and sharing.Using the XML style language to realize the data translation and manifestation can satisfy various kinds of users' demands.Since many of XML' s advantages could not be found in memory,how to store and manage the XML data effectively has become a hot research subject.Based on the XML document' s mapping rules,this paper did research into normalized storage of XML schema from the perspective of keeping semantic constraints.It includes: description of the XML document in mapping rules;discussion of a new method of generating XML key based on table tree from mapping rules;discussion of the definition of both simplified keys and simplified functional dependencies and of the translation from keys to simplified functional dependencies based on the connection between XML keys and functional dependencies;discussion of the translation from XML schema to relation schema and presentation of a new translation algorithm based on XML key.This algorithm can keep functional dependency and lossless connection to divide the universal relation into 3rd normal form schema set,and it can make the derived relation schema reasonable.The contributions of this paper are as follows:(1)Referencing to the definition of XML mapping rules,we present the definition of the universal relation and the correlative mapping rules on XML document.(2)A algorithm for intelligent extending to efficiently deriving XML keys based on XML document is proposed.Firstly we present Label Key file able to store a lot of key character strings which can foreseeably and exclusively mark the other data,and it is dynamically updated in the algorithm running. Then the algorithm derives the key set from the table tree of mapping rules,and present the analysis and proof of this algorithm.(3)A new normalized translation method is proposed for translating XML schema to relational schema,without the DTD (Document Type Description).Firstly XML key set is translated into simplified functional dependencies,which can reduce the redundancy of attribute nodes.Divide the universal relation into relational normal form while keeping functional dependency,and ensure the relational table and its attributes of the derived relational schema reasonable.The method has been proved to be valid from the view of theory and experiment.