RDF::Core is a pure perl implementation of RDF storage, parser,
serializer and query.

The storage functionality is basic - store, delete, query statements,
where query means ask about existence or count or retrieve statements
conforming given mask of (subject, predicate, object).  Three storages
are available - in memory, file (DB_File) and DBMS (PostgreSQL).

The parser supports full RDF/XML syntax including aboutEach attribute
(though it became obsolete).

The serializer attempts to preserve anonymous nodes and to compact xml a
bit grouping statements with common subject.

The query language is rather focused on resources than on statements.