Optimizing XSLT based on input XML document structure description and translating XSLT into equivalent XQuery expressions

• US 7,949,941 B2
• Filed: 10/28/2005
• Issued: 05/24/2011
• Est. Priority Date: 04/22/2005
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Novoselsky, Anguel, Krishnaprasad, Muralidhar, Liu, Zhen Hua
• Primary Examiner(s): Ries; Laurie
• Assistant Examiner(s): Dyer; Andrew R
• Application Number:
  US11/261,684
• Publication Number:
  US 20060242563A1
• Time in Patent Office: 2,034 Days
• Field of Search: None
• US Class Current: 715/234
• CPC Class Codes: G06F 40/143 Markup, e.g. Standard Generalized Markup Language [SGML] or Document Type Definition [DTD]
• CPC Class Codes: G06F 40/154 Tree transformation for tree-structured or markup documents, e.g. XSLT, XSL-FO or stylesheets

Abstract

Transformation of a set of XML documents via an XSLT stylesheet is made more efficient by rewriting the stylesheet at compile-time, based on the structural description of the set of XML documents, into an optimized stylesheet containing fewer dynamic template-matching calls than the original stylesheet. This rewritten stylesheet can be further rewritten into a set of XQuery expressions. At compile-time, the particular transformation templates that are appropriate for transforming the particular nodes contained in the set of XML documents are determined, and XSLT calls to the templates are converted to calls to corresponding XQuery user-defined functions. Determination of the appropriate transformation templates may be based on the structural description of the input set of XML documents, such as an XML Schema or Document Type Definition. The data from each template is translated into corresponding XQuery constructors, instructions from the template are translated into XQuery expressions, and the XQuery functions are inlined if possible.

Claims

1. A method comprising:

receiving a request to transform a set of one or more XML documents based at least in part on an XSLT stylesheet that includes calls to one or more transformation templates, wherein each transformation template specifies how to transform one or more nodes, wherein the one or more nodes include a first node and a descendant node of the first node, wherein the calls to the one or more transformation templates, if evaluated based on the XSLT stylesheet, would use an XSLT template matching process to associate the descendant node in the set of one or more XML documents with a transformation template;

determining, based at least in part on a structural description that constrains the set of one or more XML documents to a hierarchy of nodes that may be present in the set of one or more XML documents, which one or more transformation templates to use to transform the set of one or more XML documents, wherein the hierarchy of nodes includes the first node and the descendant node; and

converting the calls in the XSLT stylesheet that would use the one or more transformation templates into calls to one or more XQuery user-defined functions, and including the calls to the one or more XQuery user-defined functions in a set of one or more XQuery language expressions;

wherein the calls to the one or more XQuery user-defined functions do not use the XSLT template matching process;

wherein the method is performed by one or more computing devices.

2. The method of claim 1, further comprising:

translating the one or more XQuery language expressions into one or more corresponding SQL database statements; and

submitting the one or more database statements to a database server for execution of the one or more database statements.

3. The method of claim 1, wherein the determining further comprises:

based at least in part on the structural description that constrains the set of one or more XML documents to the hierarchy of nodes that may be present in the set of one or more XML documents, constructing a corresponding sample document that represents the structure of the set of one or more XML documents;

submitting the sample document to an XSLT engine for transformation based at least in part on the XSLT stylesheet and for tracing execution paths associated with the transformation, wherein the execution paths indicate, for particular nodes contained in the sample document, which particular transformation template to use to transform the corresponding particular node.

4. The method of claim 3, wherein the converting further comprises:

accessing a mapping, resulting from the sample document execution path tracing, that identifies a particular template used to transform a particular node in the sample document and defines a corresponding XQuery user-defined function that corresponds to the particular template;

wherein selecting the particular template is based at least in part on template matching criteria defined in the XSLT stylesheet.

5. The method of claim 3, wherein constructing the sample document includes constructing the sample document using an XML schema to which the set of one or more XML documents conforms.

6. The method of claim 3, wherein constructing the sample document includes constructing the sample document using a Document Type Definition to which the set of one or more XML documents conforms.

7. The method of claim 3, wherein constructing the sample document includes constructing the sample document using a relational or object- relational schema based at least in part on which the set of one or more XML documents is constructed.

8. The method of claim 3, wherein constructing the sample document includes constructing the sample document using a data guide to which the set of one or more XML documents structurally conforms.

9. The method of claim 3, wherein determining which particular one or more transformation templates to use to transform the set of one or more XML documents includes:

accessing a mapping resulting from the sample document execution path tracing, wherein the mapping indicates, for each node that may be contained in the XML document, which particular template to use to transform the corresponding node.

10. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

for each of the one or more templates to use to transform the XML document, translating data from the template to one or more XQuery constructors; and

translating instructions from the template to one or more XQuery expressions.

11. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

apply-templates”

instruction into a set of XQuery conditional expressions to call an XQuery user-defined function, wherein the set of XQuery conditional expressions are based at least in part on a template matching pattern for a corresponding template in the XSLT stylesheet, and wherein the XQuery user-defined function is based at least in part on the body of the template.

12. The method of claim 11, wherein translating the “

xsl;

apply-templates”

instruction into the set of XQuery conditional expressions includes;

including, in each XQuery conditional expression, a template matching pattern from the XSLT stylesheet.

13. The method of claim 11, wherein translating the “

xsl;

apply-templates”

instruction into a-the set of XQuery conditional expressions includes;

including, in each XQuery conditional expression, calls to a corresponding XQuery user-defined function.

14. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

call-template”

instruction into an XQuery language expression that calls a corresponding XQuery user-defined function, wherein the corresponding XQuery user-defined function is based at least in part on the body of a corresponding template of the one or more templates.

15. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

representing non-recursive template calls or corresponding non-recursive user-defined XQuery functions in-line in the one or more XQuery language expressions.

16. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

element”

instruction into an XQuery element constructor.

17. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating “

xsl;

attribute”

or “

xsl;

attribute-set”

instructions into an XQuery attribute constructor.

18. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

processing-instruction”

instruction into an XQuery processing instruction constructor.

19. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes :

translating an “

xsl;

comment”

instruction into an XQuery comment constructor.

20. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

text”

instruction into an XQuery text constructor.

21. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating “

xsl;

choose”

, “

xsl;

otherwise”

, or “

xsl;

when”

instructions into an XQuery conditional expression.

22. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

foreach”

instruction into an XQuery FOWR expression.

23. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

sort”

instruction into an XQuery order by expression;

translating a ‘

number’

datatype for xsl;

sort into an XQuery order by with xs;

double( ) function; and

translating a ‘

text’

datatype for xsl;

sort into an XQuery order by with xs;

string( )function.

24. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

variable”

instruction to declare a global variable into an XQuery global variable declaration expression.

25. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

variable”

instruction to declare a local variable into an XQuery LET variable definition expression.

26. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an XSLT instruction that does not have a corresponding direct XQuery expression construct into an XQuery function that is implemented natively by a host XQuery processor.

27. The method of claim 1, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an XSLT stylesheet embedded in an XML document into an XQuery language expression by translating data from the XML document into one or more XQuery constructor expressions and translating the embedded XSLT stylesheet into a set of one or more XQuery language expressions.

28. The method of claim 1, wherein the XSLT stylesheet is a first XSLT stylesheet, further comprising:

at request compile time, computing a rewritten XSLT stylesheet by rewriting the first XSLT stylesheet;

wherein computing the rewritten XSLT stylesheet includes said step of determining, based at least in part on the structural description that constrains the set of one or more XML documents to the hierarchy of nodes that may be present in the set of one or more XML documents, which particular one or more transformation templates to use to transform the set of one or more XML documents; and

wherein the rewritten XSLT stylesheet includes fewer dynamic template matching calls than the first XSLT stylesheet.

29. The method of claim 28, wherein structural description is an XML Schema to which the one or more XML documents structurally conform.

30. The method of claim 28, wherein the structural description is a Document Type Definition to which the set of one or more XML documents structurally conform.

31. The method of claim 28, wherein determining which one or more transformation templates to use to transform the set of one or more XML documents comprises:

based at least in part on the structural description that constrains the set of one or more XML documents to the hierarchy of nodes that may be present in the set of one or more XML documents, constructing a corresponding sample document that represents possible structures of the XML documents in the set of one or more XML documents;

submitting the sample document to an XSLT engine for transformation based at least in part on the XSLT stylesheet and for tracing execution paths associated with the transformation, wherein the execution paths indicate, for each node contained in the sample document, which particular transformation template to use to transform the corresponding node.

32. A non-transitory computer-readable storage medium storing instructions, which, when executed by one or more computing devices, cause the one or more computing devices to perform:

receiving a request to transform a set of one or more XML documents based at least in part on an XSLT stylesheet that includes calls to one or more transformation templates, wherein each transformation template specifies how to transform one or more nodes, wherein the one or more nodes include a first node and a descendant node of the first node, wherein the calls to the one or more transformation templates, if evaluated based on the XSLT stylesheet, would use an XSLT template matching process to associate the descendant node in the set of one or more XML documents with a transformation template;

determining, based at least in part on a structural description that constrains the set of one or more XML documents to a hierarchy of nodes that may be present in the set of one or more XML documents, which transformation templates to use to transform the set of one or more XML documents, wherein the hierarchy of nodes includes the first node and the descendant node; and

converting the calls in the XSLT stylesheet that would use the one or more transformation templates into calls to one or more XQuery user-defined functions, and including the calls to the one or more XQuery user-defined functions in a set of one or more XQuery language expressions;

wherein the calls to the one or more XQuery user-defined functions do not use the XSLT template matching process.

33. The non-transitory computer-readable storage medium of claim 32, wherein the determining further comprises:

based at least in part on the structural description that constrains the set of one or more XML documents to the hierarchy of nodes that may be present in the set of one or more XML documents, constructing a corresponding sample document that represents the structure of the set of one or more XML documents;

submitting the sample document to an XSLT engine for transformation based at least in part on the XSLT stylesheet and for tracing execution paths associated with the transformation, wherein the execution paths indicate, for particular nodes contained in the sample document, which particular transformation template to use to transform the corresponding particular node.

34. The non-transitory computer-readable storage medium of claim 32, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

for each of the one or more templates to use to transform the XML document, translating data from the template to one or more XQuery constructors; and

translating instructions from the template to one or more XQuery expressions.

35. The non-transitory computer-readable storage medium of claim 32, wherein the XSLT stylesheet is a first XSLT stylesheet, and wherein the instructions, when executed by one or more computing devices, cause the one or more computing devices to further perform:

at request compile time, computing a rewritten XSLT stylesheet by rewriting the first XSLT stylesheet;

wherein computing the rewritten XSLT stylesheet includes said step of determining, based at least in part on the structural description of nodes contained in the set of that constrains the set of one or more XML documents to the hierarchy of nodes that may be present in the set of one or more XML documents, which particular one or more transformation templates to use to transform the set of one or more XML documents; and

wherein the rewritten XSLT stylesheet includes fewer dynamic template matching calls than the first XSLT stylesheet.

36. The non-transitory computer-readable storage medium of claim 34, wherein the structural description is an XML schema to which the one or more XML documents structurally conform.

37. The non-transitory computer-readable storage medium of claim 34, wherein the structural description is a Document Type Definition to which the one or more XML documents structurally conform.

38. The non-transitory computer-readable storage medium of claim 32, wherein the instructions, when executed by one or more computing devices, cause the one or more computing devices to further perform:

translating the one or more XQuery language expressions into one or more corresponding SQL database statements; and

submitting the one or more database statements to a database server for execution of the one or more database statements.

39. The non-transitory computer-readable storage medium of claim 32, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

representing non-recursive template calls or corresponding non-recursive user-defined XQuery functions in-line with the one or more XQuery language expressions.

40. The non-transitory computer-readable storage medium of claim 32, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating “

xsl;

choose”

, “

xsl;

otherwise”

, or “

xsl;

when”

instructions into an XQuery conditional expression.

41. The non-transitory computer-readable storage medium of claim 32, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an “

xsl;

sort”

instruction into an XQuery order by expression;

translating a ‘

number’

datatype for xsl;

sort into an XQuery order by with xs;

double() function; and

p1 translating a ‘

text’

datatype for xsl;

sort into an XQuery order by with xs;

string()function.

42. The non-transitory computer-readable storage medium of claim 32, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an XSLT instruction that does not have a corresponding direct XQuery expression construct into an XQuery function that is implemented natively by a host XQuery processor.

43. The non-transitory computer-readable storage medium of claim 32, wherein translating the XSLT stylesheet into the set of one or more XQuery language expressions includes:

translating an XSLT stylesheet embedded in an XML document into an XQuery language expression by translating data from the XML document into one or more XQuery constructor expressions and translating the embedded XSLT stylesheet into a set of one or more XQuery language expressions.

44. The non-transitory computer-readable storage medium of claim 32, wherein the determining further comprises:

based at least in part on the structural description that constrains the set of one or more XML documents to the hierarchy of nodes that may be present in the set of one or more XML documents, constructing a corresponding sample document that represents the structure of the set of one or more XML documents;

submitting the sample document to an XSLT engine for transformation based at least in part on the XSLT stylesheet and for tracing execution paths associated with the transformation, wherein the execution paths indicate, for particular nodes contained in the sample document, which particular transformation template to use to transform the corresponding particular node.

45. The non-transitory computer-readable storage medium of claim 44, wherein the converting further comprises:

accessing a mapping, resulting from the sample document execution path tracing, that identifies a particular template used to transform a particular node in the sample document and defines a corresponding XQuery user-defined function that corresponds to the particular template;

wherein selecting the particular template is based at least in part on template matching criteria defined in the XSLT stylesheet.

46. The non-transitory computer-readable storage medium of claim 44, wherein constructing the sample document includes constructing the sample document using an XML schema to which the set of one or more XML documents conforms.

47. The non-transitory computer-readable storage medium of claim 44, wherein constructing the sample document includes constructing the sample document using a Document Type Definition to which the set of one or more XML documents conforms.

48. The non-transitory computer-readable storage medium of claim 44, wherein constructing the sample document includes constructing the sample document using a relational or object-relational schema based at least in part on which the set of one or more XML documents is constructed.

49. The non-transitory computer-readable storage medium of claim 44, wherein constructing the sample document includes constructing the sample document using a data guide to which the set of one or more XML documents structurally conforms.

50. The non-transitory computer-readable storage medium of claim 44, wherein determining which one or more transformation template to use to transform the set of one or more XML documents includes:

accessing a mapping resulting from the sample document execution path tracing, wherein the mapping indicates, for each node that may be contained in the XML document, which particular template to use to transform the corresponding node.