The following feature requests and bug reports are known:

Next
* implement DAIA/RDF 

Bugfix
* change XML namespace from http://ws.gbv.de/daia/ to http://purl.org/NET/DAIA ?
* better catch XML parsing errors, show this in client example

Additional functionality
* add inferencing (same id = same object policy)
* add support of logging with Log4Perl
* add 'limited' property to a response (or just open world assumption?)
* ->provideXXX(...)?
* extenden limitation with from, until, embargo 
  (see http://scholar.google.com/intl/en/scholar/institutional_holdings.xml)

Additional methods
* validating as method (move code from daia.pl)
* add 'removeMessages([lang])' ? can be solve with grep!
* user-defined XML-namespace-prefix in XML serialization

More tests and documentation
* better describe how to add properties (add/provide) and to query the structure
* document and test setting via unblessed struct
* test UTF-8 (when reading from streams), append*, ...
* more serialization and unserialization
* does it work on Windows ?

Misc
* minimize package dependencies