Proxy doesn't do well, if preferredRecordSyntax is not set.

Per database config.

Control the various optimizations with config..
  query match
  record caching
  fix-up reference ID
  pre-init
  keepalive
  -1 reinit.

Live status (via search, present).

Possible threading.

Character set conversion for SRW queries.

Throw proper CQL conversion error.

Honor XPath.