VTL is a standard language for defining validation and transformation rules (set of operators, their syntax and semantics) for any kind of statistical data.
VTL builds on the Transformation section of the SDMX information model, by taking the common parts of GSIM, SDMX and DDI as for the representation of concepts and data. The assumption is that such a logical formalization of validation and transformation rules will provide a "technology-neutral" expression at business level of the processing taking place, against which various implementations and specific programming languages can be mapped.
The specifications for exchanging VTL validation rules in SDMX messages, for storing rules and for requesting validation rules from web services will be provided in a specific update to the SDMX Technical Standards on which the SDMX Technical Working Group is working on.
The current official version of the language is v2.1 and it includes:
- User Manual highlighting the main characteristics of VTL, its core assumptions and the information model the language is based on;
- Reference Manual, describing the full library of operators ordered by category, with examples;
- EBNF notation (Extended Backus-Naur Form) grammar, which is the technical notation to be used as a test bed for all the examples throughout the document: files Vtl.g4 & VtlTokens.g4
- Technical Notes document, to support VTL implementation
generate_tck_files.py allows you to generate a zip containing all the examples for a given version of VTL.
The proposed structure allows obtaining the script, the necessary datasets as input and the datasets to be tested as output.
v2.1 is the only supported version for now.
git clone https://github.com/sdmx-twg/vtl.git
cd vtl/scripts
DOC_VERSION=v2.1 python3 generate_tck_files.pyGithub action releases TCK zip each time vX/docs/reference_manual/operators is updated.
For instance, for v2.1, you can access directly to the zip through http with https://sdmx-twg.github.io/vtl/tck/v2.1.zip url.