Providing a common interface for discovery, exploration of metadata and querying of different types of data sources. With MetaModel you get a uniform connector and query API for:
PostgreSQL
MySQL
Oracle
SQL Server
Apache Hive
Embedded DBs
CouchDB MongoDB HBase Cassandra ElasticSearch DynamoDB Salesforce.com
SugarCRM CSV files
Spreadsheets XML files
JSON files MetaModel isn't a data mapping framework. Instead we emphasize abstraction of metadata and ability to add data sources at runtime, making MetaModel great for generic data processing applications, less so for applications modeled around a particular domain.
https://metamodel.apache.org/