[WEB4LIB] Re: Z39.50 Discussion on Web4Lib

[Matthew Dovey]

> Actually, it was "only" 100 targets, but Matthew is correct that we

Oh sorry!!

> There *are* scalability issues, but my sense is in practice they will have
> more to do with quality-of-service and reliability issues (ie. if you
> search 500 targets, do you *need* a response from each one).

There is another scalability issue - if you are searching 500 targets you
are like to get 500 times as many hits, so the user needs to put in more
specific queries. Also the necessity for dedup begins to surface.

> Perhaps the most important issue, and one which is sometimes ignored in
> discussions of Z39.50-based virtual union catalogs of any form, has to do
> with server-side scalability (rather than client-side scalability, which
is
> where the "mystic" bottlenecks are quoted). Many library systems in
smaller
> libraries are really only scaled to handle a handful of workstations and
> perhaps the odd web-user visitng the OPAC from home.

This is certainly an issue I met in at least one UK union catalogue project
(I think I refered to this at the ZIG) - the systems were in small music
conservatiores and scaled to support a few OPACs on site. This lead to three
issues - the server wasn't scaled to above half a dozen users, the licensing
for the system was per user and typically only covered a dozen simultaneous
users, and the network connection was poor!

However, the essential point is that these are no Z39.50 issues, but general
issues which infortunately this use of Z39.50 tends to expose...

Matthew