The AMI (ATLAS Metadata Interface) 2.0 metadata ecosystem: new design principles and features.

AMI (ATLAS Metadata Interface) is a generic ecosystem for metadata aggregation, transformation and cataloguing. Benefitting from more than 15 years of feedback in the LHC context, the second major version was recently released. We describe the design choices and their benefits for providing high-level metadata-dedicated features. In particular, we focus on the implementation of the Metadata Querying Language (MQL), a domain-specific language allowing to query databases without knowing the relation between entities. Finally, we emphasise the assets of the ecosystem for deploying an AMI service and extending its functionalities.