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LASXML, Validation, and RELAX NG
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Have all configuration information in XML. Be ... Well formed' vs. valid' 10% of XML documents have errors! Well formed' means that the XML syntax is correct. ... – PowerPoint PPT presentation
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Title: LASXML, Validation, and RELAX NG
1
LAS-XML, Validation, and RELAX NG
- Jon Callahan(standing in for Roland Schweitzer)
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LAS use of XML
- LAS (will) store all configuration information
in XML documents - Server configuration
- User Interface components
- Dataset descriptions
- Variables
- User Interface presentation
- Product generation hints
- Data access hints
3
LAS use of XML
4
Sister servers
5
Improving our use of XML
- GOALS
- Have all configuration information in XML
- Be able to create a schema for validation
- Better separate UI vs. product server info
- Expanded set of information
- Clean up inconsistencies
6
New dataset XML
- ltlasdata version"6.5"gt
- ltdataset
- doc"http//www.cdc.noaa.gov/cdc/data.coad
s.ltm.html" - ID"CDC014"
- name"COADS LTMs"gt
- ltvariable
- ID"V2"
- name"Sea Surface Temperature"
- units"degC"
- url"file//Datasets/coads_2d_g_std/ss
t.mean.ncsst"gt - ltgrid IDREF"G88"/gt
- lt/variablegt
- ltvariablegt lt/variablegt
- lt/datasetgt
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New dataset XML
- ltgrid ID"G88"gt
- ltaxis IDREF"CDC014-lon17"/gt
- ltaxis IDREF"CDC014-lat18"/gt
- ltaxis ID"CDC014-time88" type"t"
units"month"gt - ltarange size"120" start"1990-01-01"
step"1"/gt - lt/axisgt
- lt/gridgt
- ltaxis ID"CDC014-lon17" type"x"
units"degrees_east"gt - ltarange size"180" start"1" step"2"/gt
- lt/axisgt
- ltaxis ID"CDC014-lat18" type"y"
units"degrees_north"gt - ltarange size"90" start"-89" step"2"/gt
- lt/axisgt
- lt/lasdatagt
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Well formed vs. valid
- 10 of XML documents have errors!
- Well formed means that the XML syntax is
correct. - Valid means that the XML conforms to a schema
(or DTD). - Tools are available to validate XML against your
schema. - Automatic validation means less user support!
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Writing schemas with RELAX NG
- RELAX NG is a newly popular tool for writing XML
schemas. - RELAX NG focuses on XML tree structure(not
element content). - RELAX NG schemas are easy to write.
- RELAX NG schemas are easy to read.
- Working with RELAX NG is fun! (Roland)
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RELAX NG schema for ltlasdatagt
- ltdefine name"Lasdata"gt
- ltelement name"lasdata"gt
- ltattribute name"version"/gt
- ltinterleavegt
- ltoneOrMoregt
- ltref name"Dataset"/gt
- lt/oneOrMoregt
- ltoneOrMoregt
- ltref name"Grid"/gt
- lt/oneOrMoregt
- ltoneOrMoregt
- ltref name"Axis"/gt
- lt/oneOrMoregt
- lt/interleavegt
- lt/elementgt
- lt/definegt
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Useful links
- The RELAX NG Tutorial at Oasis.
- A 3-part series of "XML Matters" columns entitled
"Kicking back with RELAX NG" by David Mertz (Part
1, Part 2, and Part 3). - An article about the design philosophy behind
RELAX NG. - The text of a book on RELAX NG to be published by
O'Reilly Associates. - A C-library that includes RELAX NG validation
with Perl bindings via XML-LibXML.
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