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Re: Distributed searches in Z39.50?

From: Ben Soares <Ben.Soares@ed.ac.uk>
Date: Mon, 19 Apr 2004 14:56:42 +0100
To: "NJ Rogers, Learning and Research Technology" <Nikki.Rogers@bristol.ac.uk>
Cc: Alex Khokhlov <alex@lib.msu.ru>, "'Alan Kent'" <ajk@mds.rmit.edu.au>, www-zig@w3.org
Message-Id: <200404191456.42360.Ben.Soares@ed.ac.uk>

Hello all,

Nikki's description of Xgrain project/GetRef service is accurate, though let 
me expand a little as I'm one of the developers.

The focus of GetRef is on Abstracting & Indexing databases available to the 
UK HE/FE (mainly HE), though of course the technology could be deployed 

GetRef provides a brokering service with (currently) a web interface and a 
Z39.50 target.  Searches on these get distributed concurrently across the 
list of configured end-resources (which the end-user is authorised to use, 
since most of the resources require an institutional subscription).  We 
intend to create an SRW/U service on top of this too.  Only a few 
access-points are searchable, but this is perhaps the nature of 
cross-searching large numbers of resources.  Incidentally, the modular 
nature of construction means that the end-resources do not need to be 
Z39.50 targets themselves, though that seems to be the most popular means 
of m2m searching.  We are currently developing screen-scraping (ugh!) 
capabilities where necessary.  The authentication/authorisation issues are 
no minor part either!
The returned records are normalised into something hopefully still useful.  
Having a focus on A&I dbs is a help here.

As for client notification, this isn't available in the Z30.50 target, 
though we may look into it in future.  I hadn't realised that there was a 
prescribed way of doing this in Z39.50 and have been reading this thread 
with interest.  We were thinking more along the lines of adding additional 
functionality to an SRW service (on the appropriate hooks) to allow 
"query-monitoring" and perhaps linking this to Z39.50 queries too (so you 
could make a query with a simple zclient, and monitor its progress using 
SOAP queries...?).
We've been working with SPP to make the Z39.50 server more useful in terms 
of its cross-search functionality (must resume this!).

I would quite like to see us also create some kind of unbuffered 
event-driven SOAP response which could provide a single query with a single 
response with realtime information, though I suppose the client would have 
to be threaded to make good use of that, and it probably wouldn't allow for 
retrieval of records before the whole search had finished.

Our web interface allows result components to be reported as they happen, 
and for searches to be put in the background whilst existing records are 
viewed, though this is just using internal communication.

Unfortunately there are no plans to make the Xgrain/GetRef code open 
source :(

See <http://edina.ac.uk/getref/> for more details!


On Mon, 19 April, 2004 13:07, NJ Rogers, Learning and Research Technology 
> Hi
> >> My curiosity was a little different - I was wondering how to expose
> >> a Z39.50 interface instead of a web interface. That is, develop a
> >> server that allowed Z39.50 clients to access it where the server
> >> forwarded requests on to all the remote servers, did the query
> >> translations, record normalization, etc.
> Just for information - some projects here in the UK (HE/FE) that are
> probably relevant to your discussion:
> 1) The EDINA GetRef service
> http://edina.ac.uk/getref/
> (was previously the Xgrain project -
> http://edina.ed.ac.uk/projects/joinup/xgrain/)
> This represents a broker service - to remote Z39.50 and other services.
> 2) The Subject Portals Project
> http://www.portal.ac.uk/spp/
> I am a developer on 2). We have developed a xsearch portlet for 2), the
> functionality of which will ultimately be abstracted. Hence it will
> represent a cross-searching client in essence, capable of concurrently
> searching Z39.50 (and other types of) targets.  In developing this
> xsearch portlet we have also targeted 1) as a means of including
> additional multiple targets via a broker. There have been lots of issues
> along the way, these will get documented as project outputs and I believe
> the source code will be made freely available (not sure which license
> yet!) at the project end.  The project (2) will conclude August of this
> year.
> Nikki

Ben Soares                              	   tel:	+44 (0)131-651 1238
EDINA, Edinburgh University Data Library	   fax:	+44 (0)131-650 3308
Main Library Building, George Square    	 email:	ben.soares@ed.ac.uk
Edinburgh EH8 9LJ, Scotland, UK         	   www:	http://edina.ac.uk/

"Hmmm, that makes no sense to me...
 But then you are very small, perhaps you're right." -- Treebeard
Received on Monday, 19 April 2004 09:57:42 UTC

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