There is no synchronous operation in SRU.   

As for federated  search .  

To digress a moment, you may recall -- I believe it was on this list --
there was discussion (maybe a year ago?) of what that even means and whether
it is the same or differs from metasearch, whatever that means.  That
discussion was inconclusive.  Anyway, earlier drafts of SRU 2.0  describe a
metasearch model.  Recently, the committee decided that the terms
"metasearch" and "federated search" are undefined jargon.  We now choose to
call it "multi-server search".

So to answer the question of whether there is federated search support: yes,
limited support, if by federated search you mean multi server search.   

There is no multi-server support in terms of separate result sets for
different servers.   However,  for (1) faceted search results, and (2)
subquery results, these can be grouped according to server. 

--Ray



-----Original Message-----
From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of Kuba
Sent: Tuesday, May 18, 2010 4:07 AM
To: [log in to unmask]
Subject: Re: [CODE4LIB] OASIS SRU and CQL, access to most-current drafts

Hi,

Does the current draft include any support for asynchronous operation of the
protocol (either by status notifications and polling and/or streaming), e.g
some chunk of results coming back before others?
Sometime ago I read through an early draft published on the LOC site and it
mentioned support for federated search but it's hard to imagine how could
that be implemented without any async support.