Streaming XML data retrieval using XPath

• US 7,877,366 B2
• Filed: 03/14/2005
• Issued: 01/25/2011
• 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
• Primary Examiner(s): Trujillo; James
• Assistant Examiner(s): BURKE, JEFF A
• Application Number:
  US11/080,794
• Publication Number:
  US 20050203957A1
• Time in Patent Office: 2,143 Days
• Field of Search: 707/702, 715/234
• US Class Current: 707/702
• 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 is provided. XPaths and associated content handlers instances are registered at runtime with the XML Extractor. The XML Extractor 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, the XML Extractor generates 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;

said stream-based parser receiving at runtime, a set of XPaths and associated content handler instances for registration;

wherein each XPath of the set of registered XPaths is associated with a separate content handler of a plurality of content handlers that are registered with said stream-based parser;

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;

in response to detecting that received streaming input includes an XPath that matches a registered XPath, reading registration information to identify a particular content handler instance that has been registered for said registered XPath, and calling said particular content handler instance;

wherein the steps of receiving, evaluating, and detecting are performed by one or more computing devices.

2. The method of claim 1, wherein the particular content handler instance implements an interface selected from the group consisting of XMLSerializer and XMLSequenceBuilder.

3. The method of claim 1, wherein the particular content handler instance implements an interface for reporting start of XPath events and end of XPath events.

4. 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.

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

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

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

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

9. The method of claim 8, 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.

10. 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.

11. The method of claim 10, wherein the tree that represents a structural hierarchy is a XPath dependency tree that consolidates common elements of registered XPaths.

12. The method of claim 10, 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.

13. The method of claim 10, 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.

14. A computer-readable storage medium storing one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

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

said stream-based parser receiving at runtime, a set of XPaths and associated content handler instance for registration;

wherein each XPath of the set of registered XPaths is associated with a separate content handler of a plurality of content handlers that are registered with said stream-based parser;

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;

in response to detecting that received streaming input includes an XPath that matches a registered XPath, reading registration information to identify a particular content handler instance that has been registered for said registered XPath, and calling said particular content handler instance.

15. The computer-readable storage medium of claim 14,

wherein the particular content handler instance implements an interface selected from the group consisting of XMLSerializer and XMLSequenceBuilder.

16. The computer-readable storage medium of claim 14,

wherein the particular content handler instance implements an interface for reporting start of XPath events and end of XPath events.

17. The computer-readable storage medium of claim 14,

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.

18. The computer-readable storage medium of claim 14,

wherein said streaming input comprises an XML document.

19. The computer-readable storage medium of claim 14,

wherein said streaming input comprises XML data from a web services application.

20. The computer-readable storage medium of claim 14,

wherein said stream-based parser comprises a SAX parser.

21. The computer-readable storage medium of claim 14,

wherein at least one XPath in the set of XPaths includes a location path and a predicate.

22. The computer-readable storage medium of claim 21,

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.

23. The computer-readable storage medium of claim 14,

additionally comprising instructions which, when executed by the one or more processors, causes the one or more processors to perform:

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

24. The computer-readable storage medium of claim 23,

wherein the tree that represents a structural hierarchy is a XPath dependency tree that consolidates common elements of registered XPaths.

25. The computer-readable storage medium of claim 23,

additionally comprising instructions which, when executed by the one or more processors, causes the one or more processors to perform:

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.

26. The computer-readable storage medium of claim 23,

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.