VO Data Modeling Language Specification

Current WD:

• VO-DML: a consistent modelling language for IVOA data models (docx, pdf)

The documentation collaborative page, including ongoing versions and other documentation, is located at volute although this should not be used as an official reference

Schema files providing normative definitions vor valid VO-DML/XML files can be found here:

• XML schema (XSD) for main structure of document: https://volute.g-vo.org/svn/trunk/projects/dm/vo-dml/xsd/vo-dml-v1.0.xsd
• Schematron for extra rules that cannot be (easily) implemented in XSD: https://volute.g-vo.org/svn/trunk/projects/dm/vo-dml/xsd/vo-dml.sch.xml

[GL 2014-04-25: I will try to keep track of comments from the mailing list on this page

A set of data models created according to the specification can be found on volute as well in the dm/vo-dml/models folder. Of special relevance for this specification are

• ivoa: a core model defining various primitive types as well as quantity types. This model should be reused by all other models.
• photdm-alt: a version of the photdm data model, should be synchronized with that spec.
• source: TOY model for describing astronomical sources. ONLY used in the VO-DML and UTYPE specs for illustrating the various modelling and mapping concepts. The real source model is still ongoing.

We have made a first superficial pass at porting other IVOA data models to VO-DML, in particular characteriation, stc, simdm. These can be used as starting points for a more formal IVOA DM effort to create VO-DML representations for all models, but such an effort MUST include domain experts for those models, i.e. likely the original modellers.

Both DatasetMetadata and [https://volute.g-vo.org/svn/trunk/projects/dm/vo-dml/models/STC2/][STC2] have been ported to the last VO-DML version (Spring 2016).

Many of these models have been created from a UML definition using an XSLT script available in the xslt sub-folder. For each model an HTML documentation file has been generated from the vo-dml/xml representation using another xslt script. These can be executed using appopriate ttargets in the ant build.xml file. This also contains a target for validating vo-dml/xml files, which is especially useful for such files written by hand.

Please read the README.txt for a first draft of a documentation of the structure of the vo-dml folder on volute and and hints how to use the ant build.xml script for the various XSLT scripts. This documentation will be copied on this page over time.

A model template template has been made available for Modelio 3.0 has. It must be first imported in Modelio and then used as a base for the new model. Before to be converted in VO-DML, the model must be exported as an XMI (UML2.4) file. The others steps are described in README.txt. In some cases the XMI file must be patched by hand (UML namspace 1st row) to pass the VO-DML transformation. This has been tested on Lunix with Modelio 3.0 and on MacOS (El Captain) with Modelion 3.3.