TODO list for Perl module PS::IPP::IData

- validation of URIs
- test that client->delete_instance removes the storage object too
- review caching of database statement handles
- code tiding/consistency
- volume handling for instance placement
- file creation retrying
- server config file
- make Apache::DBI behave
- split SOAP out of Client.pm
- error string support
- support volume with move/copy
- port to Apache2/mp2

distant future
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- cache some database tables (updated at some interval) 
- volume size/% in-use discovery
- server side per client lock tracking
- per client authentication
- client side lookup table of filehandles/locks
- Perl only?, scoped lock release/filehandle destruction
