What is DDI-CDI?
DDI Cross-Domain Integration (DDI-CDI) enhances the DDI suite of standards by adding the capability to describe key elements of data structure and process/provenance for integrating data coming from different sources. While it can be used on its own, it is designed to act as a supplement to domain-specific models for describing data (ontologies, vocabularies, DDI Codebook, DDI Lifecycle, etc.). It is built on the detailed "DDI Moving Forward" model which also is utilized by the DDI Lifecycle standard, making these compatible (e.g., they both use the same model of variables).
DDI-CDI is expressed as a formal Unified Modeling Language (UML) model, expressed in interchangeable Canonical XMI (and XML format). It can be implemented using any desired technology - many good tools exist for leveraging UML models in this way. This guarantees that in any domain or system, the normal technology can be used (XML, RDF, JSON, Java, SQL, etc.). While it is primarily intended for use across domain and discipline boundaries, often the challenges of data integration also exist within domains. It is a suitable model for addressing these as well.