schema-gen

Schema generation

For generating XML Schema (XSD) and JSON Schema artifacts from Metaschema source.

Depends on datatype definitions in subdirectory (submodule) ../support/metaschema/schema.

See the file manifest for a survey of file contents by file.

Currently, schemas in two formats are supported, with a third under development:

• XSD (version 1.1)
• JSON Schema (v 7)
• InspectorXSLT - schema and Schematron emulator for XML, v0.8

Producing schemas for a single metaschema source

Schema generation from NIST Metaschema source data is currently supported by XSLT in this subdirectory. This can be done in any of several ways as is convenient for a developer, tester or Metaschema end user (metaschema author or developer):

• make files supporting the testing and production infrastructure
• Command line scripts calling Apache Maven for Java configuration and support
• calling XSLT directly the same transformations can be executed directly from an environment already supporting XSLT
• using XProc the same transformations are orchestrated using XProc for efficiency and speed

Currently, all these assume a single top-level metaschema as input, with its modules called via import.

Routines that provide the same services over sets or batches of metaschemas, for efficiency, are to be developed.

Produce an XSD using make

Currently the make infrastrucutre supports only high-level testing - see make help.

Schema generation logic (or other utilities useful to developers) can be added to the Makefile as needed.

Produce an XSD with a script (calling Maven)

With Apache Maven installed, to produce a single standalone XSD from a single metaschema source, use the bash script mvn-xsd-schema-xsl.sh:

/path/to/mvn-xsd-schema-xsl.sh metaschema.xml schema.xsd

where metaschema.xml is the name (path) of your metaschema input file (top-level component), and schema.xsd is the name of the XSD file generated as a result.

Produce an XSD calling Saxon/XSLT directly

The shell script in the preceding command works by invoking an XSLT transformation. The same XSLT can be also executed directly using Saxon (up to Saxon 10) and the following command line flags (bindings):

• -xsl (stylesheet) - nist-metaschema-MAKE-XSD.xsl
• -s (source document) - your metaschema
• -o (result path) - where to write your XSD

Note: Saxon 11 is being tested. See the Issue tracker for more info.

Produce any kind of schema using Saxon/XSLT

The same pattern works for any schema supported, with any of the following XSLT transformations:

• XSD (XML Schema Definition Language) - nist-metaschema-MAKE-XSD.xsl
• JSON Schema v7 as JSON - nist-metaschema-MAKE-JSON-SCHEMA.xsl
• JSON Schema v7 as XML (for debugging) - nist-metaschema-MAKE-JSON-SCHEMA-as-xml.xsl
• InspectorXSLT - schema validation emulator with experimental implementation of Metaschema Constraints - nist-metaschema-MAKE-INSPECTOR-XSLT.xsl

One of these stylesheets, when run on a top-level metaschema module, will deliver the appropriate output as directed by the -o flag or by a consuming application.

Produce all schemas at once, with a script

The Maven configuration is also set up for XML Calabash, an implementation of XProc.

This is helpful since all schema outputs can be produced together from a given metaschema, more efficiently than one at a time.

/path/to/mvn-xsd-schema-xsl.sh metaschema.xml newschema

where metaschema.xml is the source metaschema, and newschema is a label to be prepended to XSD and JSON Schema output file names, in this case newschema.xsd and newschema.json.

Using XProc directly

An XProc 1.0 engine can be configured with the pipeline METASCHEMA-ALL-SCHEMAS.xpl and run directly. It assumes a single top-level metaschema as input, and produces multiple outputs on multiple ports:

• -i input port METASCHEMA for the metaschema
• -o output port INT_0_echo-input echoes the input
• -o INT_1_composed-metaschema=/dev/null after composition
• -o OUT_json-schema-xml JSON Schema in XML format
• -o OUT_json-schema JSON Schema in JSON
• -o OUT_xml-schema XML Schema (XSD)

This pipeline is used by the mvn-schemas-xpl.sh script.

It can also be run independently to help in debugging.

For metaschema composition, this pipeline uses the subpipeline ../compose/metaschema-compose.xpl.

Acquiring Saxon sources

curl -s -o SaxonHE12-3J.zip https://www.saxonica.com/download/SaxonHE12-3J.zip

curl -s -o SaxonHE12-2J.zip https://www.saxonica.com/download/SaxonHE12-2J.zip