System and method of translating a relational database into an XML document and vice versa

Abstract

A method of translating a relational database into an XML document comprises generating an Extended Entity Relationship model from relational schema associated with the relational database and applying a schema translation process to the Extended Entity Relationship model to map the relational schema into a Document Type Definition (DTD) of an XML schema. An XML Tree Model is then generated from the Document Type Definition, the XML Tree Model being representative of one or more data semantics of the relational schema which are preserved as one or more data semantics in the XML document. Relational data from the relational database is then converted into the XML document using the relational schema and the XML schema from the Document Type Definition and/or the XML Tree Model. There is also described a method of translating an XML database into a relational database which comprises the reversal of the steps of the aforementioned method, and a system for implementing both methods.

1 . A method of translating a relational database into an XML document comprising the steps of: 
 generating an Extended Entity Relationship (EER) model from relational schema associated with said relational database;    applying a schema translation process to the Extended Entity Relationship model to map the relational schema into a Document Type Definition (DTD) of an XML schema;    generating a XML Tree Model from said Document Type Definition representative of one or more data semantics of the relational schema which are preserved as one or more data semantics in said XML document; and    converting relational data from said relational database into said XML document using said relational schema and said XML schema from said Document Type Definition and/or said XML Tree Model.    
   
   
       2 . A method according to  claim 1 , wherein the step of generating said Extended Entity Relationship model comprises reverse-engineering logical relational schema associated with said relational database.  
   
   
       3 . A method according to  claim 1 , wherein the step of applying a schema translation process comprises mapping the relational schema with associated relational schema constraints into said Document Type Definition.  
   
   
       4 . A method according to  claim 1 , wherein the step of applying a schema translation process comprises mapping the relational schema into a topological XML Document Type Definition.  
   
   
       5 . A method according to  claim 1 , where the step of applying a schema translation process comprises defining a root element prior to mapping the relational schema into said Document Type Definition (DTD), said root element being representative of an element in said relational database.  
   
   
       6 . A method according to  claim 5 , wherein the step of defining a root element comprises selecting said root element.  
   
   
       7 . A method according to  claim 5 , wherein the step of defining a root element comprises selecting said root element from a relational entity table in said relational database.  
   
   
       8 . A method according to  claim 5 , wherein said relational database comprises one or more entities, and said XML document comprises said root element, and one or more sub-elements, and wherein the step of applying a schema translation process further comprises one or more of the following steps after defining said root element: 
 (a) mapping a weak entity from said relational database into said XML document;    (b) mapping participation between entities in said relational database into said XML document;    (c) mapping cardinality between entities in said relational database into said XML document;    (d) mapping aggregation between entities in said relational database into said XML document;    (e) mapping one or more is a relationships between entities in said relational database into said XML document;    (f) mapping one or more generalisations between entities in said relational database into said XML document;    (g) mapping one or more categorisations between entities in said relational database into said XML document; and    (h) mapping one or more single and/or multiple (n-ary) relationships between entities in said relational database into said XML document.    
   
   
       9 . A method according to  claim 1 , wherein said relational database comprises one or more entities, and said XML document comprises said root element, and one or more sub-elements, and wherein the step of applying a schema translation process comprises mapping related entities in said relational database into relevant elements in said XML document based on navigability of the entities.  
   
   
       10 . A method according to  claim 1 , wherein the step of converting relational data from said relational database into said XML document comprises: 
 (a) converting one or more relations associated with relational data in said relational database into a Document Object Model (DOM); and    (b) manipulating said XML document using said Document Object Model.    
   
   
       11 . A method according to  claim 10 , wherein said Document Object Model (DOM) is a Java Document Object Model (JDOM).  
   
   
       12 . A method according to  claim 5 , wherein each mapping step generates a new XML document, and wherein the step of converting relational data from said relational database into said XML document comprises: 
 (a) converting one or more relations associated with relational data in said relational database into a Document Object Model (DOM); and    (b) integrating XML documents using said Document Object Model to form an XML database corresponding to said relational database.    
   
   
       13 . A method according to  claim 1  wherein the step of generating an XML Tree Model comprises generating a plurality of XML Tree Models representative of one or more data semantics of the relational schema.  
   
   
       14 . A method according to  claim 12 , further comprising updating said relational database and said XML database by translating an update transaction from said relational database in Structural Query Language into an update transaction of said XML database as a Document Object Model.  
   
   
       15 . A method according to  claim 14 , wherein said transactions update said relational database and said XML database concurrently to produce a synchronized update.  
   
   
       16 . A method according to  claim 14 , wherein said updating of said relational database is effected prior to or after said update of said XML database to produce an asynchronized update.  
   
   
       17 . A method according to  claim 1 , wherein the step of generating an Extended Entity Relationship (EER) model comprises recovering one or more data semantics associated with said relational schema from a classification table.  
   
   
       18 . A method of translating an XML database into a relational database comprising the steps of: 
 generating an XML Tree Model from said XML database;    generating a Document Type Definition representative of one or more data semantics of an XML schema associated with said XML database;    generating an Extended Entity Relationship (EER) model from said XML schema;    applying a schema translation process to the Extended Entity Relationship model to map the XML schema into a relational schema representative of said relational database, said data semantics of said XML schema being preserved as one or more data semantics in said relational database; and    converting XML data from said XML database into said relational database using said relational schema and said XML schema from said Document Type Definition and/or said XML Tree Model.    
   
   
       19 . A method according to  claim 18 , wherein the step of generating said Extended Entity Relationship model comprises reverse-engineering logical relational schema associated with said relational database.  
   
   
       20 . A method according to  claim 18 , wherein the step of applying a schema translation process comprises mapping the XML schema with associated XML schema constraints into said Document Type Definition.  
   
   
       21 . A method according to  claim 18 , wherein the step of applying a schema translation process comprises mapping a topological XML Document Type Definition into said Extended Entity Relationship.  
   
   
       22 . A method according to  claim 18 , wherein said XML schema comprise one or more elements each having an associated data occurrence, and wherein the step of applying a schema translation process further comprises for each element in said XML schema, locating a corresponding target relation, and loading into a tuple of said target relation the data occurrence of said element according to one or more data semantics of said XML database.  
   
   
       23 . A method according to  claim 18 , wherein the step of generating an XML Tree Model comprises generating a plurality of XML Tree Models representative of one or more data semantics of the XML schema.  
   
   
       24 . A method according to  claim 18 , further comprising updating said relational database and said XML database by translating an update transaction from said XML database as a Document Object Model into an update transaction of said XML database in Structural Query Language.  
   
   
       25 . A method according to  claim 24 , wherein said transactions update said relational database and said XML database concurrently to produce a synchronized update.  
   
   
       26 . A method according to  claim 24 , wherein said updating of said relational database is effected prior to or after said update of said XML database to produce an asynchronized update.  
   
   
       27 . A method of data transmission of relational data through an XML document between a sender and a receiver over a network comprising the method of  claim 1  for translating relational data into an XML document, transmitting from said sender said XML document over said network, receiving at said receiver said XML document, and converting said XML document into a relational language used in said receiver.  
   
   
       28 . A method according to  claim 27 , wherein the step of converting said XML document into a local relational schema used in said receiver comprises: 
 generating an XML Tree Model from said XML document;    generating a Document Type Definition representative of one or more data semantics of an XML schema associated with said XML document;    generating an Extended Entity Relationship (EER) model from said XML schema;    applying a schema translation process to the Extended Entity Relationship model to map the XML schema into said local relational schema representative of a relational database of said receiver, said data semantics of said XML schema being preserved as one or more data semantics in said relational database of said receiver; and    converting XML data from said XML database into said local relational database using said local relational schema and said XML schema from said Document Type Definition and/or said XML Tree Model.    
   
   
       29 . A method according to  claim 28 , wherein said network is the Internet.  
   
   
       30 . A method according to  claim 28 , wherein said network is the Internet.  
   
   
       31 . A computer program comprising program instructions for causing a computer to perform the method of  claim 1 .  
   
   
       32 . A computer program comprising program instructions for causing a computer to perform the method of  claim 18 .  
   
   
       33 . A computer program product comprising the computer program of  claim 31 .  
   
   
       34 . A computer program product comprising the computer program of  claim 32 .  
   
   
       35 . A system arranged to perform the method of  claim 1 .  
   
   
       36 . A system arranged to perform the method of  claim 18 .  
   
   
       37 . A system of translating a relational database into an XML document comprising: 
 an Extended Entity Relationship (EER) model generator for generating an Extended Entity Relationship (EER) model from relational schema associated with said relational database;    means for applying a schema translation process to the Extended Entity Relationship model to map the relational schema into a Document Type Definition (DTD) of an XML schema;    a generator for generating an XML Tree Model from said Document Type Definition representative of one or more data semantics of the relational schema which are preserved as one or more data semantics in said XML document; and    a converter for converting relational data from said relational database into said XML document using said relational schema and said XML schema from said Document Type Definition and/or said XML Tree Model.    
   
   
       38 . A system of translating an XML database into a relational database comprising: 
 an XML Tree Model generator for generating an XML Tree Model from said XML database;    a Document Type Definition generator for generating a Document Type Definition representative of one or more data semantics of an XML schema associated with said XML database;    an Extended Entity Relationship (EER) model generator for generating an Extended Entity Relationship (EER) model from said XML schema;    means for applying a schema translation process to the Extended Entity Relationship model to map the XML schema into a relational schema representative of said relational database, said data semantics of said XML schema being preserved as one or more data semantics in said relational database; and    a converter for converting XML data from said XML database into said relational database using said relational schema and said XML schema from said Document Type Definition and/or said XML Tree Model.