native OODBMS for CLI

 db4o is the open source object database that enables Java and .NET developers
 to store and retrieve any application object with only one line of code,
 eliminating the need to predefine or maintain a separate, rigid data model.
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 This is the native CLI version of db4o for Mono and Microsoft .NET Framework,
 but there is also a native Java version, check http://www.db4o.com.