Method and system for supporting XQuery trigger in XML-DBMS based on relational DBMS

• US 20060129575A1
• Filed: 10/27/2005
• Published: 06/15/2006
• Est. Priority Date: 12/14/2004
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Kim, Myung Joon, Won, Jong Ho, Lee, Mi Young, Lee, Myung Cheol
• Granted Patent: US 7,392,259 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/8358 Query translation
• CPC Class Codes: Y10S 707/954 Relational
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A method and system for supporting an XQuery trigger in XML-DBMS based on relational DBMS is provided. In an Ubiquitous environment where XML data are incessantly generated by an enormous number of objects, so as to overcome inconvenience and its resultant reduction of performance in which a user should query after checking a change of XML-DBMS one by one, in XML-DBMS based on relational DBMS, the present invention supports an XQuery trigger technique based on SQL trigger automatically executing insert, update and delete statements, and a storage or external procedure related with the change of data when a change of data is generated at a specific table in a conventional relational DBMS.

Claims

1. A method for supporting an XQuery trigger in XML-DBMS based on a relational DBMS, the method comprising:

a first step of registering an XML schema, a relational DBMS schema, and a mapping rule of the XML schema and the relational DBMS schema through an XML database layer so as to store, manage and search XML data in the relational DBMS;

a second step of, in case where a user creates an XQuery trigger following a statement structure of XQuery being a standard of an XML query language, automatically creating an SQL trigger having the relational DBMS schema as a query target, using the mapping rule of the first step, from the XQuery trigger having the XML schema as a query target, and returning the XML result set so that the user can access the latest result set of the automatically executed XQuery trigger; and

a third step of, whenever the XML data is added, changed or deleted in the XML-DBMS layer, automatically changing the relational DBMS, and informing the user of the facts of the change of the XML database and the execution of the XQuery trigger so that the user can access the latest execution result of the XQuery trigger through the XML result set that is returned when the XQuery trigger is created in the second step,

whereby a query is automatically executed depending on the change of the XML data, and its result is monitored.

2. The method of claim 1, wherein the first step further comprises:

a step 1-1 of, if the XML/SQL mapping rule is registered and completed, creating an SQL table for storing and managing the XML data in the relational DBMS, from the relational DBMS schema; and

a step 1-2 of registering mapping information, such as an XML schema name, an XML schema file, a corresponding relational DBMS table name list, and a mapping rule file of the XML schema and the SQL schema, to a metadata table.

3. The method of claim 1, wherein the second step comprises:

a step 2-1 of user'"'"'s creating an XQuery trigger following a statement structure of XQuery being the standard of the XML query language having the XML schema registered in the first step as a query target; and

a step 2-2 of analyzing the statement structure of the XQuery, creating an XQuery statement tree if there is no problem in analysis, extracting XML schema information as the target for the query in the created XQuery statement tree, checking whether or not there is the XML schema previously registered in the first step, checking whether or not the SQL schema associated with a corresponding XML schema exists in the relational DBMS, and if there is no problem, loading the mapping rule registered in the first step from the metadata table and building a memory data structure;

a step 2-3 of traversing the XQuery statement tree while converting the XQuery trigger into a corresponding SQL trigger, creating a trigger table for creating the SQL trigger statement, and creating a temporary table for keeping the execution result of the SQL trigger statement, in the relational DBMS; and

a step 2-4 of creating the SQL trigger statement, and constructing an SQL result set for the temporary table so that the user can access all the records of the temporary table, lapping the constructed SQL result set to the XML result set, and returning the XML result set to the user.

4. The method of claim 3, wherein the user requests the creation of the XQuery trigger, by inputting an observable object as a medium for informing the change fact of the XML-DBMS to the user.

5. The method of claim 3, wherein the memory data structure can be built when a system is initially activated without re-creating the XQuery triggers.

6. The method of claim 1, wherein the third step comprises:

a step 3-1 of storing the XML data conforming to the XML schema registered in the first step, in the XML-DBMS;

a step 3-2 of, if the user requests a storage of the XML data, constructing a DOM tree being a standard of an XML document object model through a statement analysis process of the XML data received as the input element; and

a step 3-3 of loading the mapping rule registered in the first step and constructing a memory data structure, and then converting the DOM tree into an INSERT statement of SQL and storing the converted DOM tree in the relational DBMS.

7. The method of claim 6, wherein the step 3-3 changes the relational DBMS tables associated with the XML schema and the trigger table created in the second step, an execution of the SQL trigger created in the second step within the relational DBMS is caused, and the SQL trigger execution result is kept in the temporary table created in the second step and automatically reflected in the XML result set.

8. The method of any one of claims 1 to 7, wherein the XQuery trigger is classified, depending on a method for operating the XML data using the XQuery statement within the trigger, into the following:

a storage XQuery trigger for, upon the change of the XML-DBMS, processing the change item and storing new XML data,

a change XQuery trigger for, upon the change of the XML-DBMS, changing other XML data using information provided from the change item,

a delete XQuery trigger for, upon the change of the XML-DBMS, deleting other XML data using information provided from the change item, and

a search XQuery trigger for, upon the change of the XML-DBMS, executing a query for the object of a total XML data set having the change item, and returning its result to the user.

9. The method of claim 8, wherein in the search XQuery trigger, the execution result of the XQuery trigger is again returned to the user, and the user registers the observable object to the XML-DBMS so that the execution fact of the XQuery trigger can be notified to the user, thereby making it possible to notify the user.

10. A system for supporting an XQuery trigger in XML-DBMS based on a relational DBMS, the system comprising:

a metadata manager for processing and managing an XML schema, a relational DBMS schema, and a mapping rule of the XML schema and the relational DBMS schema;

an XML data processor for converting the XML data to be stored in the XML-DBMS into an INSERT statement of SQL, for statement analyzing and storing the XML data in the relational DBMS; and

an XQuery trigger processor for analyzing the XQuery trigger statement created by the user, creating a trigger table and a temporary table for SQL trigger, converting the XQuery trigger statement into a corresponding SQL trigger sentence and creating the SQL trigger in the relational DBMS, and providing an XML result set for the temporary table to the user.

11. The system of claim 10, wherein the XML data processor further comprises an XML statement analyzer and an XML data converter.

12. The system of claim 10, wherein the XQuery trigger processor further comprises an XQuery statement analyzer, an XQuery converter, and an XML tagger.

13. The system of claim 12, wherein the XML tagger stores the XML data through the XML data processor while converting a result of tuple format of the automatically executed SQL trigger in a format of the XML data, and providing the converted result to the user.