Method, computer program product, and system converting relational data into hierarchical data structure based upon tagging trees

• US 20050138052A1
• Filed: 02/26/2004
• Published: 06/23/2005
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Padmanabhan, Sriram, Zhou, Nianjun, Meliksetian, Dikran S., Mihaila, George Andrei
• Granted Patent: US 7,219,102 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/284 Relational databases
• CPC Class Codes: Y10S 707/956 Hierarchical
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation

Abstract

Tagging trees are generated and used to facilitate transforming data from relational databases into hierarchical formats, such as in XML documents. Tagging trees contain both XML hierarchical structure information as well a query information that is needed to access different data sources, e.g., databases, to retrieve the information to be placed in the hierarchical structure. A designer optionally creates a mapping script that specifies the transformation from relational databases to the hierarchical format. A tagging tree is created by either parsing that mapping script or by other means. A runtime environment then processes the tagging tree by a depth first traversal. The runtime environment is able to be configured to output a hierarchical data object, such as an XML document, or pipelined to control, for example, SAX processing.

Claims

1. A method for defining data transfer from a database into a hierarchical structure, the method comprising:

generating a tagging tree that corresponds to a mapping between a relational database and a hierarchical data structure, the tagging tree comprising a plurality of nodes, at least one of the nodes having a node type, selected from the group of node types consisting of execution node, data node, binding node, attribute node, and element node;

traversing at least one node of the tagging tree;

retrieving, in response to traversing an execution node, a data object from the at least one relational database as specified in the execution node; and

inserting, in response to a data node and based upon the mapping, the data object into an output conforming to the hierarchical structure.

2. The method of claim 1, wherein the traversing comprises a depth-first tree traversal algorithm.

3. The method of claim 1, wherein the generating comprises one of generating the tagging tree programmatically and parsing the external mapping script, the external mapping script specifying a mapping of data between at least one relational database table and a hierarchical data structure.

4. The method of claim 1, wherein the traversing comprises:

determining a node type for a current node, the determining a node type comprising reading a node identifier;

performing, based upon the node type, one of the retrieving and the inserting; and

traversing to a next node.

5. The method of claim 4, wherein the retrieving comprises:

executing a query over the at least one relational database to retrieve the data object; and

storing the data object as a set of tuples in a temporary staging area, and

wherein the inserting comprises accessing the data object stored within the set of tuples.

6. The method of claim 1, wherein the inserting is performed in accordance with a sequence of performing the traversing.

7. A data transformation processor comprising:

a tagging tree generator that generates a tagging tree that corresponds to a mapping between a relational database and a hierarchical data structure, the tagging tree comprising a plurality of nodes, at least one of the nodes having a node type, selected from the groups of node types consisting of execution node, data node, binding node, attribute node, and element node; and

a runtime environment that;

traverses at least one node of the tagging tree;

retrieves, in response to traversing an execution node, a data object from the at least one relational database as specified in the execution node; and

inserts, in response to a data node and based upon the mapping, the data object into an output conforming to the hierarchical structure.

8. The data transformation processor of claim 7, wherein the runtime environment traverses at least one node by using a depth-first tree traversal algorithm.

9. The data transformation processor of claim 7, wherein the tagging tree generator generates by one of generating the tagging tree programmatically and parsing the external mapping script, the external mapping script specifying a mapping of data between at least one relational database table and a hierarchical data structure.

10. The data transformation processor of claim 7, wherein the runtime environment traverses by:

determining a node type for a current node, the determining a node type comprising reading a node identifier;

performing, based upon the node type, one of the retrieving and the inserting; and

traversing to a next node.

11. The data transformation processor of claim 10, wherein the runtime environment retrieves by:

executing a query over the at least one relational database to retrieve the data object; and

storing the data object as a set of tuples in a temporary staging area, and

wherein the inserting comprises accessing the data object stored within the set of tuples.

12. The data transformation processor of claim 7, wherein the runtime environment inserts in accordance with a sequence in which the runtime environment traverses.

13. A computer program product for defining data transfer from a database into a hierarchical structure, the computer program product comprising:

a storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising;

generating a tagging tree that corresponds to a mapping between a relational database and a hierarchical data structure, the tagging tree comprising a plurality of nodes, at least one of the nodes having a node type, selected from the group of node types consisting of execution node, data node, binding node, attribute node, and element node;

traversing at least one node of the tagging tree;

retrieving, in response to traversing an execution node, a data object from the at least one relational database as specified in the execution node; and

inserting, in response to a data node and based upon the mapping, the data object into an output conforming to the hierarchical structure.

14. The computer readable medium of claim 13, wherein the traversing comprises a depth-first tree traversal algorithm.

15. The computer readable medium of claim 13, wherein the generating comprises one of generating the tagging tree programmatically and parsing the external mapping script, the external mapping script specifying a mapping of data between at least one relational database table and a hierarchical data structure.

16. The computer readable medium of claim 13, wherein the traversing comprises:

determining a node type for a current node, the determining a node type comprising reading a node identifier;

performing, based upon the node type, one of the retrieving and the inserting; and

traversing to a next node.

17. The computer readable medium of claim 16, wherein the retrieving comprises:

executing a query over the at least one relational database to retrieve the data object; and

storing the data object as a set of tuples in a temporary staging area, and

wherein the inserting comprises accessing the data object stored within the set of tuples.

18. The computer readable medium of claim 13, wherein the inserting is performed in accordance with a sequence of performing the traversing.