Survey of XML Query Languages

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Survey of XML Query Languages

• Josh Spiegel

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What is an XML Query Language?
Roughly like SQL but for XML instead of
relational data.
ltemployeesgt ltemployee id1gt ltnamegtJohn
Coltranelt/namegt ltsalarygt152156lt/salarygt lt/emplo
yeegt ltemployee id2gt ltnamegtMaceo
Parkerlt/namegt ltsalarygt82654lt/salarygt lt/employee
gt ltemployee id3gt ltnamegtJosh
Spiegellt/namegt ltsalarygt35250lt/salarygt lt/employe
egt lt/employeesgt
I want all the employees that make more than
50,000.
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The Languages
Chances are, if you ever end up using an XML
query language, you will use XQuery.
XML-QL
The High Bit
XQuery
Lorel
Quilt
SQL/XML

• Almost a W3C recommendation
• Already the de facto standard
• There are many implementations

(ANSI/ISO)
XPath
CXQuery
XML-GL
XSL
XQL
Active XQuery
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Comparative Analysis

• Comparative Analysis of Five XML Query Languages
  by Angela Bonifati and Stefano CeriSIGMOD
  Record 2000
• 27 Features an XML Query Language should have
• Uses the features to compare 5 languages
• Lorel
• XML-QL
• XML-GL
• XSL
• XQL
• ADDED XQuery

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Expectations

• We expect XQuery to do better than the other 5
  languages.
• The other languages are roughly grandparents of
  XQuery.
• XQuery is the de facto standard.
• XQuery will soon be a W3C recommendation.

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XQuery could have done better

• Where it did well
• Integration of XML Schema
• Where it needs improvement
• Insert, update, delete
• Full support for XPointer and XLink
• XQuery working group indicates these features
  will be added in the future.
• Implementations support features not in the
  language specification.

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Integration of XML Schema

• XML Schema / DTD define the structure, content
  and semantics of XML documents e.g. xsdinteger
• XQuery will never require a XML Schema
• When a schema is available, more static checks
  are possible

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Integration of XML Schema

• ltemployeesgt
• ltemployee id1gt
• ltnamegtJohn Coltranelt/namegt
• ltsalarygt152156lt/salarygt
• lt/employeegt
• ltemployee id2gt
• ltnamegtMaceo Parkerlt/namegt
• ltsalarygt82654lt/salarygt
• lt/employeegt
• ltemployee id3gt
• ltnamegtJosh Spiegellt/namegt
• ltsalarygtpeanutslt/salarygt
• lt/employeegt
• lt/employeesgt

Query What is the average salary?
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Integration of XML Schema

• ltemployeesgt
• ltemployee id1gt
• ltnamegtJohn Coltranelt/namegt
• ltsalarygt152156lt/salarygt
• lt/employeegt
• ltemployee id2gt
• ltnamegtMaceo Parkerlt/namegt
• ltsalarygt82654lt/salarygt
• lt/employeegt
• ltemployee id3gt
• ltnamegtJosh Spiegellt/namegt
• ltsalarygtpeanutslt/salarygt
• lt/employeegt
• lt/employeesgt

Query What is the average salary?
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THE END