If we constructed a Donantonio query it supposes that we do it because we have some class of interest in the referred resources. In that case it's interesting to be able to have them quickly in local way.
For that nothing else easy that to reply them maintaining a synchronous copy of each one of them.
Having the descriptions of our pleasure and since the resources are accessible via Internet it's almost trivial to design a tool that reply them.
The uses are many and varied:
creation of departmental e-libraries
preparation of gathered cdroms.
maintenance of Linux distributions.