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 VTL 1.0 package includes:
- Part 1, highlighting the main characteristics of VTL, its core assumptions and the information model the language is based on;
- Part 2, containing the full library of operators ordered by category, including examples; this first version can support validation and basic compilation needs. Future versions, whose design is already in progress, will include more features related to transformation of data;
- EBNF notation (Extended Backus-Naur Form) which is the technical notation to be used as a test bed for all the examples throughout the document.
Download the complete VTL 1.0 package (part 1, part 2, EBNF)
Please send your comments to the SDMX Technical Working Group (TWG) at firstname.lastname@example.org. Each email message should contain only a limited set of numbered – and possibly homogeneous – comments and should contain the elements indicated in the attached comment log.
Posted on 3 March 2015