The Data Mediation Area includes all services required to manage the registration to the infrastructure of a set of data sources and to validate their content (in the case of metadata content) with respect to given rules.  Data suorces can register as being of three typologies: OAI-PMH data sources, FTP data sources, or "manual" data sources, which will upload the data through user interfaces.

The services in the D-NET Data Layer software kit have been realized to support running metadata laboratories that satisfy such requirements. In particular, a metadata laboratory consists of a dynamic pool of running services, of the following typologies:

• Data Source Management Service: offers user interfaces to allow registration and validation of data sources and to manage the subsequent data collection workflows;
• OAI-PMH harvester Service: used to harvest metadata records from OAI-PMH compatible data sources;
• FTP Collector Service: used to collect files from FTP server data sources or from file system;
  
• OGC Harvester Service: used to collect files from OGC server data sources;
  
• Validator Service: used to check and rank the “quality” of the metadata records collected from data sources (validation is performed thanks to a configurable set of "validation rules").