Streaming validation of XML documents

• US 20070250766A1
• Filed: 04/19/2006
• Published: 10/25/2007
• Est. Priority Date: 04/19/2006
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Sedlar, Eric, Murthy, Ravi, Agarwal, Nipun, Medi, Vijay, Rabinov, Arkady
• Granted Patent: US 7,992,081 B2
• Time in Patent Office: Days
• 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 40/149 Adaptation of the text data for streaming purposes, e.g. Efficient XML Interchange [EXI] format
• CPC Class Codes: G06F 40/221 Parsing markup language streams streaming G06F40/149
• CPC Class Codes: G06F 40/226 Validation

Abstract

A method and apparatus for streaming validation of XML documents is provided. A particular event of a series of events is received. The series of events is generated as an XML document is parsed by a parser, and the received particular event indicates that the parser has encountered a particular part of the XML document. The particular part of the XML document indicated by the particular event is then received. A current validation state for the XML document is determined. The current validation state, which is one of a plurality of validation states for the XML document, indicates a validation type associated with the particular part of the XML document. Based on at least the current validation state, the particular part of the XML document is validated against an XML schema that defines the structure of the XML document.

Claims

1. A method for streaming validation of eXtensible Markup Language (XML) documents, the method comprising performing a machine-executed operation involving instructions, wherein the machine-executed operation is at least one of:

A) sending the instructions over transmission media;

B) receiving the instructions over transmission media;

C) storing the instructions onto a machine-readable storage medium; and

D) executing the instructions;

wherein the instructions, when executed by one or more processors, cause the one or more processors to perform the steps of;

receiving a particular event of a series of events which is generated as an XML document is parsed by a parser, wherein the particular event indicates that the parser has encountered a particular part of the XML document;

receiving the particular part of the XML document from the parser;

determining a current validation state for the XML document, wherein the current validation state indicates a validation type associated with the particular part of the XML document, and wherein the current validation state is one of a plurality of validation states for the XML document; and

based at least on the current validation state, validating the particular part of the XML document against an XML schema that defines the structure of the XML document.

2. The method of claim 1, wherein the step of validating the particular part of the XML document comprises maintaining a stack of stack-elements, wherein the stack-elements represent schema components of the XML schema-against which parts of the XML document are validated.

3. The method of claim 2, further comprising:

before receiving the particular event, receiving a start-document event of the series of events, wherein the start-document event indicates that the parser is beginning to parse the XML document;

generating a first stack-element, wherein the first stack-element indicates a first schema component that is associated with the XML document;

storing the first stack-element on the stack;

receiving an end-document event of the series of events, wherein the end-document event indicates that the parser has completed parsing the XML document; and

in response to receiving the end-document event, removing the first stack-element from the stack.

4. The method of claim 2, wherein the step of determining the current validation state for the XML document comprises determining the current validation state based on information that is stored in a current stack-element that is on top of the stack.

5. The method of claim 4, further comprising:

before receiving the particular event, receiving a start-element event of the series of events, wherein;

the start-element event indicates that that the parser has encountered an XML element of the XML document; and

the particular part of the XML document is a sub-element of the XML element;

wherein the step of maintaining the stack of stack-elements comprises;

generating one or more stack-elements, wherein the one or more stack-elements indicate one or more schema components that are associated with the XML element; and

storing the one or more stack-elements on the stack, wherein the one or more stack-elements include the current stack-element that is on top of the stack.

6. The method of claim 5, further comprising:

receiving an end-element event of the series of events, wherein the end-element event indicates that the parser has completed parsing the XML element;

wherein the step of maintaining the stack of stack-elements comprises removing the one or more stack-elements from the stack in response to receiving the end-element event.

7. The method of claim 4, wherein:

the particular part of the XML document is an XML element;

the current stack-element includes at least one value referencing at least one schema component of the XML schema that includes a definition of the XML element;

the step of receiving the particular part of the XML document comprises receiving a content of the XML element; and

the step of validating the particular part of the XML document comprises;

based on the current validation state, determining that the XML element is associated with a simple XML type; and

checking the content of the XML element to determine whether the content conforms to the definition of the XML element.

8. The method of claim 4, wherein the particular part of the XML document is an XML element, and wherein the step of validating the particular part of the XML document comprises determining, based on the current validation state, that the XML element is associated with a complex XML type.

9. The method of claim 8, wherein:

the current stack-element includes at least one value referencing at least one schema component of the XML schema, wherein the at least one schema component includes a definition of the XML element which indicates that the XML element includes content having a simple XML type;

the step of receiving the particular part of the XML document comprises receiving the content of the XML element; and

the step of validating the particular part of the XML document further comprises checking the content of the XML element to determine whether the content conforms to the definition of the XML element.

10. The method of claim 8, wherein:

the current stack-element includes at least one value referencing at least one schema component of the XML schema, wherein the at least one schema component includes a definition of the XML element which indicates that the XML element includes a set of attributes;

the step of receiving the particular part of the XML document comprises receiving one or more attributes that are included in the XML element; and

the step of validating the particular part of the XML document further comprises checking the one or more attributes to determine whether the one or more attributes conform to the definition of the XML element.

11. The method of claim 10, wherein:

the one or more attributes include a specific attribute that overrides the complex XML type of the XML element with a different XML type; and

the step of validating the particular part of the XML document further comprises at least one of;

modifying the information stored in the current stack-element to indicate a different validation state instead of the current validation state, wherein the different validation state reflects the different XML type; and

modifying the current stack-element to include one or more different values that reference one or more different schema components of the XML schema, wherein the one or more different schema components include a different definition of the XML element which indicates that the XML element is associated with the different XML type.

12. The method of claim 8, wherein:

the current stack-element includes at least one value referencing at least one schema component of the XML schema, wherein the at least one schema component includes a definition of the XML element which indicates that the XML element includes a set of content particles;

the step of receiving the particular part of the XML document comprises receiving one or more content particles that are included in the XML element; and

the step of validating the particular part of the XML document further comprises validating the one or more content particles against the definition of the XML element.

13. The method of claim 12, wherein the step of validating the particular part of the XML document further comprises:

generating one or more stack-elements, wherein the one or more stack-elements include one or more values referencing one or more schema components that include a particular definition of a particular content particle of the one or more content particles;

storing the one or more stack-elements on the stack; and

removing the one or more stack-elements from the stack when the step of validating the particular content particle is completed.

14. The method of claim 4, wherein the step of validating the particular part of the XML document comprises determining, based on the current validation state, that the particular part of the XML document is an XML element that is a content particle included in a parent XML element.

15. The method of claim 14, wherein:

the current validation state indicates that the XML element is an element particle of the parent XML element;

the current stack-element includes;

an occurrence count indicating the number of already validated XML elements that are the same element particles of the parent XML element as the XML element; and

at least one value referencing at least one schema component of the XML schema, wherein the at least one schema component includes a definition of the XML element;

the step of receiving the particular part of the XML document comprises receiving the XML element; and

the step of validating the particular part of the XML document further comprises validating the XML element against the definition of the XML element, wherein validating the XML element includes;

if the XML element conforms to the definition, then incrementing the occurrence count; and

if the XML element does not conform to the definition, then removing the current stack-element from the stack.

16. The method of claim 14, wherein:

the current validation state indicates that the XML element is a choice particle of the parent XML element;

the current stack-element includes;

a reference to a list of entries, wherein each entry represents a sub-element included in the XML element;

an occurrence count indicating the number of already validated XML elements that are the same choice particles of the parent XML element as the XML element; and

at least one value referencing at least one schema component of the XML schema, wherein the at least one schema component includes a definition of the XML element;

the step of receiving the particular part of the XML document comprises receiving at least one sub-element included in the XML element; and

the step of validating the particular part of the XML document further comprises validating the XML element against the definition of the XML element, wherein validating the XML element includes at least one of;

for at least one sub-element included in the XML element, creating an entry representing that sub-element and inserting that entry in the list of entries;

for each entry in the list of entries, validating at least one sub-element included in the XML element, wherein if one sub-element conforms to the definition of the XML element, then the occurrence count is incremented; and

after processing all sub-elements included in the XML element, removing the current stack-element from the stack.

17. The method of claim 14, wherein:

the current validation state indicates that the XML element is a sequence particle of the parent XML element;

the current stack-element includes;

a reference to a list of entries, wherein each entry represents a sub-element included in the XML element;

an occurrence count indicating the number of already validated XML elements that are the same sequence particles of the parent XML element as the XML element; and

at least one value referencing at least one schema component of the XML schema, wherein the at least one schema component includes a definition of the XML element;

the step of receiving the particular part of the XML document comprises receiving all sub-elements included in the XML element; and

the step of validating the particular part of the XML document further comprises validating the XML element against the definition of the XML element, wherein validating the XML element includes;

for each sub-element included in the XML element, creating an entry representing that sub-element and inserting that entry in the list of entries;

based on the list of entries, validating each sub-element included in the XML element, wherein if all sub-elements conform to the definition of the XML element, then the occurrence count is incremented; and

after processing all sub-elements included in the XML element, removing the current stack-element from the stack.

18. The method of claim 14, wherein:

the current validation state indicates that the XML element is a validate-all particle of the parent XML element;

the current stack-element includes;

a reference to a list of entries, wherein each entry represents a sub-element included in the XML element;

an occurrence count indicating the number of already validated XML elements that are the same validate-all particles of the parent XML element as the XML element; and

at least one value referencing at least one schema component of the XML schema, wherein the at least one schema component includes a definition of the XML element;

the step of receiving the particular part of the XML document comprises receiving each sub-element included in the XML element; and

the step of validating the particular part of the XML document further comprises validating the XML element against the definition of the XML element, wherein validating the XML element includes;

for each sub-element included in the XML element, creating an entry representing that sub-element and inserting that entry in the list of entries;

looping through each entry in the list of entries and validating each sub-element represented by that entry; and

after validating all sub-elements included in the XML element, removing the current stack-element from the stack.

19. The method of claim 14, wherein:

the current validation state indicates that the XML element is a group particle of the parent XML element;

the current stack-element includes;

a reference to a list of entries, wherein each entry represents a sub-element included in the XML element;

an occurrence count indicating the number of already validated XML elements that are the same group particles of the parent XML element as the XML element; and

a value referencing a schema component of the XML schema, wherein the schema component includes a definition of the XML element;

the step of receiving the particular part of the XML document comprises receiving each sub-element included in the XML element; and

the step of validating the particular part of the XML document further comprises validating the XML element against the definition of the XML element, wherein validating the XML element includes;

for each sub-element included in the XML element, creating an entry representing that sub-element and inserting that entry in the list of entries;

based on the value referencing the schema component included in the current stack-element, determining one or more schema components of the XML schema, wherein the one or more schema components include definitions for each sub-element of the XML element;

looping through each entry in the list of entries and validating each sub-element represented by that entry against a corresponding definition for that sub-element included in the one or more schema components; and

after validating all sub-elements included in the XML element, removing the current stack-element from the stack.

20. The method of claim 14, wherein:

the current validation state indicates that the XML element is a validate-any particle of the parent XML element;

the current stack-element includes;

an occurrence count indicating the number of already validated XML elements that are validate-any particles of the parent XML element; and

at least one value referencing at least one schema component of the XML schema, wherein the at least one schema component includes a definition of the XML element;

the step of receiving the particular part of the XML document comprises receiving the XML element; and

the step of validating the particular part of the XML document further comprises validating the XML element against the definition of the XML element, wherein validating the XML element includes;

determining a namespace definition for the XML element based on the definition of the XML element included in the at least one schema component;

if the XML element conforms to the namespace definition, then incrementing the occurrence count; and

removing the current stack-element from the stack.

21. The method of claim 1, wherein the particular event indicates that the parser has encountered an XML element that is associated with one of a simple XML type, a complex XML type, and a content particle type.

22. The method of claim 1, wherein the step of receiving the particular event, the step of receiving the particular part of the XML document, the step of determining the current validation state, and the step of validating the particular part of the XML document are performed by a streaming validator implemented as part of a database server.

23. The method of claim 1, wherein the parser is any one of a SAX parser and a StAX parser.

24. The method of claim 1, further comprising:

receiving a request from an application to validate the XML document;

in response to the request, performing the steps of receiving the particular event, receiving the particular part of the XML document, determining the current validation state, and validating the particular part of the XML document, for at least one part of the XML document;

generating a validation result that indicates whether the XML document was validated successfully based on performing the step of validating for the at least one part of the XML document; and

sending the validation result to the application.

25. The method of claim 1, further comprising the step of transmitting at least one event of the series of events to an event consumer.

26. The method of claim 25, wherein:

the step of validating the particular part of the XML document comprises generating a validation result that indicates whether the particular part of the XML document was validated successfully; and

the step of transmitting at least one event of the series of events comprises transmitting a specific event to the event consumer, wherein the specific event indicates that the parser has completed parsing the particular part of the XML document, and wherein the specific event is augmented to include the validation result.

27. A computer system for streaming validation of an extensible Markup Language (XML) document, comprising:

a stack of stack-elements, wherein the stack-elements represent schema components of an XML schema, wherein the XML schema defines the structure of the XML document; and

a validation driver that is operatively connected to the stack, wherein the validation driver is configured to;

receive, from a parser, a series of events which is generated as the XML document is parsed by the parser, wherein the series of events includes at least one start-element event which indicates that the parser has encountered at least one part of the XML document; and

for each of the at least one part of the XML document;

receive that particular part from the parser;

determine a current validation state for the XML document based on information that is stored in a current stack-element that is on top of the stack; and

validate that particular part based at least on the current validation state.

28. The computer system of claim 27, further comprising:

a simple type validator, wherein the simple type validator is operatively connected to the stack and is configured to validate XML elements associated with a simple XML type;

a complex type validator, wherein the complex type validator is operatively connected to the stack and is configured to validate XML elements associated with a complex XML type; and

a content particle validator, wherein the content particle validator is operatively connected to the stack and is configured to validate XML elements associated with a content particle type;

wherein, for each of the at least one part of the XML document, the main validation driver;

determines a validation type of that particular part based on the current validation state; and

based on the validation type, dispatches that particular part for validation to one of the simple type validator, the complex type validator, and the content particle validator.

29. The computer system of claim 27, wherein the main validation driver is further configured to:

receive a request from an application to validate the XML document;

generate a validation result that indicates whether the XML document was validated successfully based on the validation of the at least one part of the XML document; and

sending the validation result to the application.

30. The computer system of claim 27, wherein the main validation driver is configured to transmit the series of events received from the parser to an event consumer, wherein for each of the at least one part of the XML document, the main validation driver:

generates a validation result that indicates whether that particular part of the XML document was validated successfully; and

augments a specific event of the series of events to include the validation result, wherein the specific event indicates that the parser has completed parsing that particular part.