LAS-XML, Validation, and RELAX NG Jon Callahan (standing in for Roland Schweitzer)

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’

LAS use of XML

Sister servers

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

New dataset XML <dataset doc=" ID="CDC014" name="COADS LTMs"> <variable ID="V2" name="Sea Surface Temperature" units="degC" url="file://Datasets/coads_2d_g_std/sst.mean.nc#sst"> …

New dataset XML

‘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!

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)

RELAX NG schema for

Useful links The RELAX NG Tutorial at Oasis.RELAX NG Tutorial A 3-part series of "XML Matters" columns entitled "Kicking back with RELAX NG" by David Mertz (Part 1, Part 2, and Part 3).Part 1Part 2Part 3 An article about the design philosophy behind RELAX NG.the design philosophy behind RELAX NG The text of a book on RELAX NG to be published by O'Reilly & Associates.text of a book on RELAX NG A C-library that includes RELAX NG validation with Perl bindings via XML-LibXML.C-libraryXML-LibXML