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Premium member Presentation Transcript Querying XML Documents: Querying XML Documents Paul Cotton, Microsoft Canada XML 2002 Conference Dec 12, 2002Organization of Presentation: Organization of Presentation XML query history XML Query WG history, goals and status XML Query working drafts XQuery overview XQuery issues XQuery demo QuestionsXML query history : XML query history Early queries facilities for SGML 1998: “roll your own query language” Feb 1998: XQL proposal http://metalab.unc.edu/xql Aug 1998: XML-QL submission http://www.w3.org/TR/NOTE-xml-ql/ Dec 1998: W3C QL’98 Workshop http://www.w3.org/TandS/QL/QL98 Nov 1999: XPath Recommendation http://www.w3.org/TR/xpath W3C XML Query WG - History : W3C XML Query WG - History July 1999: Working Group proposed as part of XML Activity Phase 3 rechartering Sept 1999: WG chartered and first F2F Currently 31 W3C member companies (46 WG members) 19 F2F meetings and 120+ telcons so far Public WDs every three months Proposed recommendation(s)W3C XML Query WG - Goals: W3C XML Query WG - Goals “The goal of the XML Query WG is to produce a data model for XML documents, a set of query operators on that data model, and a query language based on these query operators.”XML Query Requirements WD: XML Query Requirements WD General Requirements Non-procedural query language XML syntax for query language but also a readable syntax Protocol independent Standard error conditions Future support for updates XML Query Data Model Requirements Built on XML Infoset and PSVI Namespace aware Support for XML Schema data types Support for inter- and intra- document references XML Query Requirements WD : XML Query Requirements WD XML Query Functionality Operators on all data types Text operators across element boundaries Support for hierarchy and sequence Ability to combine data from different locs Aggregation and sorting Combination of operators including queries as operands Support for NULL/empty values Structural preservations Identity preservation Operations on names Operations on “schemas” Extensibility ClosureXML Query Use Cases WD: XML Query Use Cases WD Use Case Organization Description, DTD/Schema, Input Data, Queries and Results Current Use Cases "XMP": Experiences and Exemplars "TREE": Queries that preserve hierarchy "SEQ" - Queries based on Sequence "R" - Access to Relational Data “STRING": String Search "NS" - Queries Using Namespaces "PARTS" - Recursive Parts Explosion "REF" - Queries based on References “STRONG” – Queries that exploit strongly typed data XML Query 1.0 Data Model WD: XML Query 1.0 Data Model WD Defines what information is available to an XML Query or XPath 2.0 processor Published jointly with XSL Working Group Infoset plus the following: Support for XML Schema data types (PSVI) Support for document collections Node-labelled tree constructor model with node identity Mapping from Infoset to Query Data Model uses Infoset terminology and is shown by exampleXML Query 1.0 Formal Semantics WD: XML Query 1.0 Formal Semantics WD XML Query Formal Semantics is used: to define XQuery and XPath semantics to support query optimization FS defines both static and dynamic semantics static semantics are presented as type inference rules, which relate XQuery/FS expressions to types dynamic, or operational, semantics are presented as value inference rules, which relate XQuery/FS expressions to values in the XML Query Data Model XQuery: A Query Language for XML: XQuery: A Query Language for XML XQuery is a functional language in which a query is represented as an expression XQuery expressions can be nested with full generality The input and output of an XQuery are instances of the XML Query Data Model Based on OQL, SQL, XML-QL, XPath Readable vs. XML syntax XQueryX: XQueryX XQueryX is an XML representation of an XQuery It was created by mapping the productions of the XQuery BNF directly into XML productions XQueryX useful to enable: Parser reuse Queries on queries Generation of queries Embedding of queries in XML documents XQuery Function and Operators WD: XQuery Function and Operators WD XML Query Functions and Operators is used: to defines basic operators and functions on the datatypes defined in XML Schema Part 2: Datatypes for use in XQuery, XPath, XSLT and other related XML standards to define operators and functions on nodes and node sequences as defined in the XQuery 1.0 and XPath 2.0 Data Model for use in XQuery, XPath, XSLT and other related XML standards Includes several new data types derived from XML Schema data types XQuery Expressions: XQuery Expressions XQuery expressions Path expressions Element constructors FLWOR expressions Expressions involving operators and functions Conditional expressions Quantified expressions List constructors Expressions that test or modify datatypes XQuery Path Expressions: XQuery Path Expressions Based on abbreviated syntax of XPath Select the second section of the fifth chapter of the doc /doc/chapter[5]/section[2] XQuery Element Constructors: XQuery Element Constructors XQuery element constructor consists of a start tag and an end tag, enclosing an optional list of expressions that provide the content of the element. Generate an <emp>element that has an “empid” attribute. The value of the attribute and the content of the element are specified by variables that are bound in other parts of the query. <emp empid = {$id}> {$name} {$job} </emp> XQuery FLWOR Expressions: XQuery FLWOR Expressions A FLWOR expression binds some expressions, applies an optional predicate and ordering, and constructs a new result. FOR and LET clauses generate a list of tuples of bound expressions, preserving document order. WHERE clause applies a predicate, eliminating some of the tuples RETURN clause is executed for each surviving tuple, generating an ordered list of outputsXQuery FLWOR Expressions: XQuery FLWOR Expressions List the titles of books published by Morgan Kaufmann in 1998. FOR $b IN document("bib.xml")//book WHERE $b/publisher = "Morgan Kaufmann" AND $b/year = "1998" RETURN $b/title List each publisher and the average price of its books. FOR $p IN distinct(document("bib.xml")//publisher) LET $a := avg(document("bib.xml") /book[publisher = $p]/price) RETURN <publisher> <name> {$p/text()} </name> <avgprice> {$a} </avgprice> </publisher> XQuery Operators and Functions: XQuery Operators and Functions Infix and prefix operators Parenthesized expressions Arithmetic and logical operators Sequence operators UNION, INTERSECT and EXCEPT Functions can be defined in XQuery XQuery Operators and Functions: XQuery Operators and Functions Find the maximum depth of the document named "partlist.xml." NAMESPACE xsd="http://www.w3.org/2001/XMLSchema-datatypes" DEFINE FUNCTION depth($e AS ELEMENT) AS xsd:integer { {-- An empty element has depth 1 --} {-- Otherwise, add 1 to max depth of children --} IF empty($e/*) THEN 1 ELSE max(FOR $c in $e/* RETURN depth($c)) + 1 } depth(document("partlist.xml")) XQuery Conditional Expressions: XQuery Conditional Expressions IF THEN ELSE construct Make a list of holdings. For journals, include the editor, and for all other holdings, include the author. FOR $h IN //holding RETURN <holding> {$h/title, IF $h/@type = "Journal" THEN $h/editor ELSE $h/author } </holding> XQuery Quantified Expressions: XQuery Quantified Expressions Existential and Universal quantifiers Find titles of books in which both sailing and windsurfing are mentioned in the same paragraph. FOR $b IN //book WHERE SOME $p IN $b//para SATISFIES contains($p, "sailing") AND contains($p, "windsurfing") RETURN $b/title Find titles of books in which sailing is mentioned in every paragraph. FOR $b IN //book WHERE EVERY $p IN $b//para SATISFIES contains($p, "sailing") RETURN $b/title Sequence-related Operators: Sequence-related Operators A sequence may be constructed by enclosing zero or more expressions separated by commas. For example: ($x, $y, $z) denotes a sequence containing three members represented by variables >> (precedes) and << (follows) boolean functions () denotes an empty sequence. XQuery Operators on Data Types: XQuery Operators on Data Types INSTANCE OF returns True if its first operand is an instance of the type named in its second operand CAST is used to convert a value from one data type to another TREAT AS causes the query processor to treat an expression as though its data type were a subtype of its static type VALIDATE executes XML Schema validation W3C XML Query WG - Status : W3C XML Query WG - Status Feb 2001 XML Query Requirements http://www.w3.org/TR/xmlquery-req June 2001 XML Syntax for XQuery 1.0: XQueryX http://www.w3.org/TR/xqueryx (out of date) W3C XML Query WG - Status : W3C XML Query WG - Status Nov 15 2002 XQuery 1.0: An XML Query Language http://www.w3.org/TR/xquery/ XML Query Use Cases http://www.w3.org/TR/xmlquery-use-cases/ XML Path Language (XPath) 2.0 http://www.w3.org/TR/xpath20/ XML Query 1.0 and XPath 2.0 Formal Semantics http://www.w3.org/TR/query-semantics/ XML Query 1.0 and XPath 2.0 Functions and Operators http://www.w3.org/TR/query-operators/ XML Query 1.0 and XPath 2.0 Data Model http://www.w3.org/TR/query-datamodel/ Next publication status WG Charter status Current XQuery Issues: Current XQuery Issues Need to close out issues to get to Last Call How to serialize XQuery results? When and how should schema validation be invoked? How to handle the new data types in Functions and Operators? What is best XML syntax for XQuery? Internationalization (I18N) issues Support for an update language Support for full-text retrieval Internationalization Issues: Internationalization Issues Internationalization issues string operations impact of “character normalization” http://www.w3.org/TR/charmod/ comparison and sorting of data specification of collations default collation (user, query or schema?) http://www.w3.org/XML/Group/xmlschema-current/lcissues.html#cotton-on-collation relationship to xml:lang attribute http://www.w3.org/TR/REC-xml#sec-lang-tag Full-Text Issues: Full-Text Issues Full-Text issues history within XML Query WG Library of Congress Use Case http://lcweb.loc.gov/crsinfo/xml/lc_usecases.html related to I18N issues amount of conformance: interface or results? Is cross-language definition of characters, words, sentences or paragraphs feasible? relationship to ISO SQL/MM Part 2: Full-Text? ftp://sqlstandards.org/SC32/WG4/Progression_Documents/CD/cd-fulltext-2001-05.pdf Early implementations: Early implementations CL-XML http://homepage.mac.com/james_anderson/XML/index.html Enosys Markets http://www.enosysmarkets.com/products/xq.html Fatdog http://www.fatdog.com/ Kawa-Query http://www.gnu.org/software/kawa/xquery/ IPSI-XQ http://xml.ipsi.fhg.de/xquerydemo Lucent http://db.bell-labs.com/galax/ Kweelt http://db.cis.upenn.edu/Kweelt/ Microsoft http://xqueryservices.com Software AG http://www.softwareag.com/developer/downloads/default.htm SourceForge http://sourceforge.net/projects/xquench/ X-Hive http://www.x-hive.com/xquery XML Global http://www.xmlglobal.com and more … XQuery demo: XQuery demo Microsoft http://xqueryservices.com Questions: Questions Today Later: pcotton@microsoft.com Feedback email list: public-qt-comments@w3.org (archived at http://lists.w3.org/Archives/Public/public-qt-comments/). Public discussion email list: www-ql@w3.org XQuery/XPath Town Hall Room 307, 7:30-9:00pm Dec 12 (tonight) You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
cotton2 Susett Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 31 Category: Education License: All Rights Reserved Like it (0) Dislike it (0) Added: January 24, 2008 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Querying XML Documents: Querying XML Documents Paul Cotton, Microsoft Canada XML 2002 Conference Dec 12, 2002Organization of Presentation: Organization of Presentation XML query history XML Query WG history, goals and status XML Query working drafts XQuery overview XQuery issues XQuery demo QuestionsXML query history : XML query history Early queries facilities for SGML 1998: “roll your own query language” Feb 1998: XQL proposal http://metalab.unc.edu/xql Aug 1998: XML-QL submission http://www.w3.org/TR/NOTE-xml-ql/ Dec 1998: W3C QL’98 Workshop http://www.w3.org/TandS/QL/QL98 Nov 1999: XPath Recommendation http://www.w3.org/TR/xpath W3C XML Query WG - History : W3C XML Query WG - History July 1999: Working Group proposed as part of XML Activity Phase 3 rechartering Sept 1999: WG chartered and first F2F Currently 31 W3C member companies (46 WG members) 19 F2F meetings and 120+ telcons so far Public WDs every three months Proposed recommendation(s)W3C XML Query WG - Goals: W3C XML Query WG - Goals “The goal of the XML Query WG is to produce a data model for XML documents, a set of query operators on that data model, and a query language based on these query operators.”XML Query Requirements WD: XML Query Requirements WD General Requirements Non-procedural query language XML syntax for query language but also a readable syntax Protocol independent Standard error conditions Future support for updates XML Query Data Model Requirements Built on XML Infoset and PSVI Namespace aware Support for XML Schema data types Support for inter- and intra- document references XML Query Requirements WD : XML Query Requirements WD XML Query Functionality Operators on all data types Text operators across element boundaries Support for hierarchy and sequence Ability to combine data from different locs Aggregation and sorting Combination of operators including queries as operands Support for NULL/empty values Structural preservations Identity preservation Operations on names Operations on “schemas” Extensibility ClosureXML Query Use Cases WD: XML Query Use Cases WD Use Case Organization Description, DTD/Schema, Input Data, Queries and Results Current Use Cases "XMP": Experiences and Exemplars "TREE": Queries that preserve hierarchy "SEQ" - Queries based on Sequence "R" - Access to Relational Data “STRING": String Search "NS" - Queries Using Namespaces "PARTS" - Recursive Parts Explosion "REF" - Queries based on References “STRONG” – Queries that exploit strongly typed data XML Query 1.0 Data Model WD: XML Query 1.0 Data Model WD Defines what information is available to an XML Query or XPath 2.0 processor Published jointly with XSL Working Group Infoset plus the following: Support for XML Schema data types (PSVI) Support for document collections Node-labelled tree constructor model with node identity Mapping from Infoset to Query Data Model uses Infoset terminology and is shown by exampleXML Query 1.0 Formal Semantics WD: XML Query 1.0 Formal Semantics WD XML Query Formal Semantics is used: to define XQuery and XPath semantics to support query optimization FS defines both static and dynamic semantics static semantics are presented as type inference rules, which relate XQuery/FS expressions to types dynamic, or operational, semantics are presented as value inference rules, which relate XQuery/FS expressions to values in the XML Query Data Model XQuery: A Query Language for XML: XQuery: A Query Language for XML XQuery is a functional language in which a query is represented as an expression XQuery expressions can be nested with full generality The input and output of an XQuery are instances of the XML Query Data Model Based on OQL, SQL, XML-QL, XPath Readable vs. XML syntax XQueryX: XQueryX XQueryX is an XML representation of an XQuery It was created by mapping the productions of the XQuery BNF directly into XML productions XQueryX useful to enable: Parser reuse Queries on queries Generation of queries Embedding of queries in XML documents XQuery Function and Operators WD: XQuery Function and Operators WD XML Query Functions and Operators is used: to defines basic operators and functions on the datatypes defined in XML Schema Part 2: Datatypes for use in XQuery, XPath, XSLT and other related XML standards to define operators and functions on nodes and node sequences as defined in the XQuery 1.0 and XPath 2.0 Data Model for use in XQuery, XPath, XSLT and other related XML standards Includes several new data types derived from XML Schema data types XQuery Expressions: XQuery Expressions XQuery expressions Path expressions Element constructors FLWOR expressions Expressions involving operators and functions Conditional expressions Quantified expressions List constructors Expressions that test or modify datatypes XQuery Path Expressions: XQuery Path Expressions Based on abbreviated syntax of XPath Select the second section of the fifth chapter of the doc /doc/chapter[5]/section[2] XQuery Element Constructors: XQuery Element Constructors XQuery element constructor consists of a start tag and an end tag, enclosing an optional list of expressions that provide the content of the element. Generate an <emp>element that has an “empid” attribute. The value of the attribute and the content of the element are specified by variables that are bound in other parts of the query. <emp empid = {$id}> {$name} {$job} </emp> XQuery FLWOR Expressions: XQuery FLWOR Expressions A FLWOR expression binds some expressions, applies an optional predicate and ordering, and constructs a new result. FOR and LET clauses generate a list of tuples of bound expressions, preserving document order. WHERE clause applies a predicate, eliminating some of the tuples RETURN clause is executed for each surviving tuple, generating an ordered list of outputsXQuery FLWOR Expressions: XQuery FLWOR Expressions List the titles of books published by Morgan Kaufmann in 1998. FOR $b IN document("bib.xml")//book WHERE $b/publisher = "Morgan Kaufmann" AND $b/year = "1998" RETURN $b/title List each publisher and the average price of its books. FOR $p IN distinct(document("bib.xml")//publisher) LET $a := avg(document("bib.xml") /book[publisher = $p]/price) RETURN <publisher> <name> {$p/text()} </name> <avgprice> {$a} </avgprice> </publisher> XQuery Operators and Functions: XQuery Operators and Functions Infix and prefix operators Parenthesized expressions Arithmetic and logical operators Sequence operators UNION, INTERSECT and EXCEPT Functions can be defined in XQuery XQuery Operators and Functions: XQuery Operators and Functions Find the maximum depth of the document named "partlist.xml." NAMESPACE xsd="http://www.w3.org/2001/XMLSchema-datatypes" DEFINE FUNCTION depth($e AS ELEMENT) AS xsd:integer { {-- An empty element has depth 1 --} {-- Otherwise, add 1 to max depth of children --} IF empty($e/*) THEN 1 ELSE max(FOR $c in $e/* RETURN depth($c)) + 1 } depth(document("partlist.xml")) XQuery Conditional Expressions: XQuery Conditional Expressions IF THEN ELSE construct Make a list of holdings. For journals, include the editor, and for all other holdings, include the author. FOR $h IN //holding RETURN <holding> {$h/title, IF $h/@type = "Journal" THEN $h/editor ELSE $h/author } </holding> XQuery Quantified Expressions: XQuery Quantified Expressions Existential and Universal quantifiers Find titles of books in which both sailing and windsurfing are mentioned in the same paragraph. FOR $b IN //book WHERE SOME $p IN $b//para SATISFIES contains($p, "sailing") AND contains($p, "windsurfing") RETURN $b/title Find titles of books in which sailing is mentioned in every paragraph. FOR $b IN //book WHERE EVERY $p IN $b//para SATISFIES contains($p, "sailing") RETURN $b/title Sequence-related Operators: Sequence-related Operators A sequence may be constructed by enclosing zero or more expressions separated by commas. For example: ($x, $y, $z) denotes a sequence containing three members represented by variables >> (precedes) and << (follows) boolean functions () denotes an empty sequence. XQuery Operators on Data Types: XQuery Operators on Data Types INSTANCE OF returns True if its first operand is an instance of the type named in its second operand CAST is used to convert a value from one data type to another TREAT AS causes the query processor to treat an expression as though its data type were a subtype of its static type VALIDATE executes XML Schema validation W3C XML Query WG - Status : W3C XML Query WG - Status Feb 2001 XML Query Requirements http://www.w3.org/TR/xmlquery-req June 2001 XML Syntax for XQuery 1.0: XQueryX http://www.w3.org/TR/xqueryx (out of date) W3C XML Query WG - Status : W3C XML Query WG - Status Nov 15 2002 XQuery 1.0: An XML Query Language http://www.w3.org/TR/xquery/ XML Query Use Cases http://www.w3.org/TR/xmlquery-use-cases/ XML Path Language (XPath) 2.0 http://www.w3.org/TR/xpath20/ XML Query 1.0 and XPath 2.0 Formal Semantics http://www.w3.org/TR/query-semantics/ XML Query 1.0 and XPath 2.0 Functions and Operators http://www.w3.org/TR/query-operators/ XML Query 1.0 and XPath 2.0 Data Model http://www.w3.org/TR/query-datamodel/ Next publication status WG Charter status Current XQuery Issues: Current XQuery Issues Need to close out issues to get to Last Call How to serialize XQuery results? When and how should schema validation be invoked? How to handle the new data types in Functions and Operators? What is best XML syntax for XQuery? Internationalization (I18N) issues Support for an update language Support for full-text retrieval Internationalization Issues: Internationalization Issues Internationalization issues string operations impact of “character normalization” http://www.w3.org/TR/charmod/ comparison and sorting of data specification of collations default collation (user, query or schema?) http://www.w3.org/XML/Group/xmlschema-current/lcissues.html#cotton-on-collation relationship to xml:lang attribute http://www.w3.org/TR/REC-xml#sec-lang-tag Full-Text Issues: Full-Text Issues Full-Text issues history within XML Query WG Library of Congress Use Case http://lcweb.loc.gov/crsinfo/xml/lc_usecases.html related to I18N issues amount of conformance: interface or results? Is cross-language definition of characters, words, sentences or paragraphs feasible? relationship to ISO SQL/MM Part 2: Full-Text? ftp://sqlstandards.org/SC32/WG4/Progression_Documents/CD/cd-fulltext-2001-05.pdf Early implementations: Early implementations CL-XML http://homepage.mac.com/james_anderson/XML/index.html Enosys Markets http://www.enosysmarkets.com/products/xq.html Fatdog http://www.fatdog.com/ Kawa-Query http://www.gnu.org/software/kawa/xquery/ IPSI-XQ http://xml.ipsi.fhg.de/xquerydemo Lucent http://db.bell-labs.com/galax/ Kweelt http://db.cis.upenn.edu/Kweelt/ Microsoft http://xqueryservices.com Software AG http://www.softwareag.com/developer/downloads/default.htm SourceForge http://sourceforge.net/projects/xquench/ X-Hive http://www.x-hive.com/xquery XML Global http://www.xmlglobal.com and more … XQuery demo: XQuery demo Microsoft http://xqueryservices.com Questions: Questions Today Later: pcotton@microsoft.com Feedback email list: public-qt-comments@w3.org (archived at http://lists.w3.org/Archives/Public/public-qt-comments/). Public discussion email list: www-ql@w3.org XQuery/XPath Town Hall Room 307, 7:30-9:00pm Dec 12 (tonight)