[WEB4LIB] Re: Z39.50

[Grace Agnew]

Everyone,

There are scalability issues with Z39.50.  Multithreaded searching of more
than 5-7 institutions at a time can result in bottlenecks due to the
client/server communications overhead.  Standards for metadata harvesting
such as OAI are emerging to address the complexity and network bottleneck
issues of Z39.50.  Z39.50 uses, eseentially, the same registry concept that
RDF, digital certificates and handles technology employ.  However, the
client/server registry adds networking overhead.  I think that future
developments ought to divorce the registry aspect of Z39.50 from the client
and server and reference instead an independent "third-party" registry.
Z39.50 should only use client/server functionality, if needed, for tuning
the search engine to address the appropriate registry.   As search engines
get smarter, even this requirement would drop off. This would integrate
Z39.50 more tightly into XML-based distributed registry implementations,
such as RDF, which has never gotten off the ground, I think because it is
bound too tightly to the individual metadata record, which makes it very
cumbersome and labor-intensive to employ.

Z39.50 has a lot to offer that simpler harvesting protocols do
not--granularity of searching to nontextual atrributes, to holdings, to
segments of hierarchical records such as EAD Finding Aids.  I think the
protocol needs some fine tuning to reflect the realities of the distributed
web networking environment but I don't think it is replaced by technologies
such as OAI, but rather complemented by them.

Grace Agnew




At 09:25 AM 02/09/2001 -0800, you wrote:
>I wonder if the person who said it was dying was referring to clients
>dying.  I read something in the last week or so from some "reliable
>source", perhaps in a recent eContent or Online, that talked about
>Z39.50 standalone clients being a dying breed, but not the whole
>protocol.  That seems fairly reasonable to me, since everything is
>moving to the browser view.
>
>I also understand that a number of ILS vendors are moving away from
>using Z39.50 as an intermediary between their native OPAC and their
>web OPAC.  Walt, what figures do you have on that?
>
>cheers
>
>dan
>
>
>Friday, February 09, 2001, 8:33:29 AM, you wrote:
>
>
>Wnro> I'm a little taken aback by that too. Let's see. ProCite and EndNote
both
>Wnro> embed Z39.50 clients. Unless I'm mistaken (quite possible), most good
>Wnro> online catalogs can serve as Z39.50 clients or Z39.50 servers. Z39.50
>Wnro> searching is fundamental to ISO-standard ILL. I know UC's statewide
system
>Wnro> makes heavy use of Z39.50, as do quite a few other systems.
>
>
>
>-- 
>Dan Lester, Data Wrangler  dan at RiverOfData.com
>3577 East Pecan, Boise, Idaho  83716-7115 USA
>www.riverofdata.com  www.postcard.org  www.gailndan.com 
>