Fwd: Re: [Yazlist] Retrieve information in a Z39.50 server

Edward C. Zimmermann edz at bsn.com
Mon Mar 26 15:27:08 CEST 2007


-- 
  E. Zimmermann, BSn/Munich R&D Unit
  Leopoldstrasse 53-55, D-80802 Munich,
  Federal Republic of Germany
  http://www.nonmonotonic.net

----- Forwarded message from "Edward C. Zimmermann" <edz at bsn.de> -----
    Date: Mon, 26 Mar 2007 12:22:37 +0200
    From: "Edward C. Zimmermann" <edz at bsn.de>
Reply-To: edz at nonmonotonic.net
 Subject: Re: [Yazlist] Retrieve information in a Z39.50 server
      To: "Discussion on the YAZ Z39.50 toolkit" <yazlist at lists.indexdata.dk>

Quoting marc <marc at indexdata.dk>:

> Carlos Escuriola wrote:
> > Hello, I'm making a final degree project in my University and I 
> > "playing" with YAZ/PHP. I want to retrieve all the information of a 
> > local Z39.50 server, store that I consider most important (autor, title, 
> > ISBN, subjects) and then show it in my own way. The problem is that I 
> > don't know if is possible to retrieve all the information of a Z39.50 
> > without making a lot of individual searching. Exists any php script to 
> > get all this information in a only (or few) step?
> > 
> 
> No. Z39.50 or SRU is not meant to copy entire collections, it's meant to 
> search  a specific small sample of records having your interest.

There is a vast difference, however, between "copying entire collections"
and harvesting information of a collection to ask the question: Where should
I search for such and such.
In Z39.50 there are various mechanisms to support the creation of locators
(explain, scan and a whole bunch of extensions).

> Many server administrators would not even like to be copied ..
> 
> If you need copying, you have to look at other protocols, like OAI for 
> example.

OAI is not for copying collections either.. (really not). OAI is for exporting
metadata (with all kinds of granularity from locator all the way up) and not
(really) the data. OAI mind and the ISO 23950 mind are not really different.
The OAI impulse came from the observation (and frustration in real life
projects) that distributed did not always work out--- what good is knowing
that the National Library in Abuja Nigeria has a good collection if I can't
reliably access it. Even in the OECD, despite high levels of broadband
deployment, availability is not always "up to standard". That said.. its
designers nearly all came from the distributed information camp and so its
"central" model is less than centralized and more distributed than any
centralist would want.

Now.. with OAI, ISO 23950 or nearly any protocol.. one needs to "connect"
to harvest. The difference between "harvest" and "search" is not always so
clear-cut.

-- 
- 
Edward C. Zimmermann, Basis Systeme netzwerk // BSn Germany
Norbert Poellmann und Edward C. Zimmermann GbR     http://www.bsn.de
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----- End forwarded message -----





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