Streaming XML data retrieval using XPath

• US 20050203957A1
• Filed: 03/14/2005
• Published: 09/15/2005
• Est. Priority Date: 03/12/2004
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Zhou, Kongyi, Wang, Jinyu, Scardina, Mark Vincent
• Granted Patent: US 7,877,366 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/86 Mapping to a database

Abstract

An XML Extractor that extracts XML data from streamed input based on registered XPaths. XPaths and associated content handlers instances are registered at runtime with the XML Extractor. The XML receives streaming input that represents XML data at a stream-based parser, and evaluates the received input against the registered XPaths expression. In response to detecting that the received streaming input includes an XPath that matches a registered XPath expression, generating output to the content handler associated with the matching registered XPath expression.

Claims

1. A method comprising the computer-implemented steps of:

receiving streaming input that represents XML data at a stream-based parser;

receiving a set of XPaths and associated content handler instances for registration;

evaluating events from the stream-based parser against the registered XPaths; and

detecting whether received streaming input includes an XPath that matches a registered XPath.

2. The method of claim 1, wherein in response to detecting that received streaming input includes an XPath that matches a registered XPath, generating output to a content handler instance associated with the matching registered XPath.

3. The method of claim 2, wherein the associated content handler instance implements an interface selected from the group consisting of XMLSerializer and XMLSequenceBuilder.

4. The method of claim 2, wherein the associated content handler instance implements an interface for reporting start of XPath events and end of XPath events.

5. The method of claim 1, wherein the step of receiving a set of XPaths and associated content handler instances for registration comprises receiving XPaths selected by a user that indicate XML data of interest in a web services application.

6. The method of claim 1, wherein said streaming input comprises an XML document.

7. The method of claim 1, wherein said streaming input comprises XML data from a web services application.

8. The method of claim 1, wherein said stream-based parser comprises a SAX parser.

9. The method of claim 1, wherein at least one XPath in the set of XPaths includes a location path and a predicate.

10. The method of claim 9, wherein said detecting that received streaming input includes an XPath that matches a registered XPath includes detecting that streaming input matches both the location path and the predicate of the at least one XPath.

11. The method of claim 1, additionally comprising the step of:

compiling registered XPaths into a tree that represents a structural hierarchy for the registered XPaths.

12. The method of claim 11, wherein the tree that represents a structural hierarchy is a XPath dependency tree that consolidates common elements of registered XPaths.

13. The method of claim 11, additionally comprising the step of:

receiving a DTD or XML schema associated with the registered XPaths;

wherein the tree that represents a structural hierarchy is a metadata tree representing the received DTD or schema, wherein nodes of said metadata tree matching registered XPaths are annotated with information about the associated registered XPath.

14. The method of claim 11, wherein the step of evaluating events from the stream-based parser against the registered XPaths comprises maintaining hierarchical relationships for received XML data in a state machine, and traversing the state machine synchronously with the tree.

15. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 1.

16. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 2.

17. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 3.

18. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 4.

19. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 5.

20. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 6.

21. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 7.

22. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 8.

23. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 9.

24. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 10.

25. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 11.

26. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 12.

27. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 13.

28. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 14.

29. A system comprising:

a streaming event-based XML parser receiving a stream of XML input data and outputting XML events;

means for registering XPaths and associated content handlers;

means for tracking XML hierarchical information about XML events received from the event-based parser;

means for determining whether a registered XPath event has occurred in the streaming XML input data by using the tracked hierarchical information

30. The system of claim 29, wherein said means for tracking XML hierarchical data includes a state machine whose state changes are triggered by XML events.

31. The system of claim 29, additionally comprising a predicate dependency table for tracking predicates associated with registered XPaths.