Wait, but in the case you suspect is common, where you return results as
soon as the first resource is returned, and subsequent results are added
to the _end_ of the list....
I'm thinking that in most of these cases, the subsequent results will be
several pages "in", and the user will never even get there. And if the
majority of users are only looking at results from one resource... why
do a broadcast multi-server search in the first place?
Peter Noerr wrote:
However things are a bit different now... At the risk of opening the debate once more
and lots of lengthy discussion let me say that our experience (as one of the handful of
commercial providers of "multi-server search engines" (MSSEs? - it'll never
stick, but I like it)) is:
1) Times are not slow for most installations as they are set by default to provide incremental
results in the fashion Jakub suggests ("First In, First Displayed"). So users see results
driven by the time of the fastest Source, not the slowest. <contentious statement>This means
that, on average, getting the results from a MSSE can be faster than doing the same search on all of
the native sites (just talking response times here, not the fact it is one search versus N). Do the
maths - it's quite fun. </contentious statement>
2) The average "delay" for just processing the results through modern MSSEs is
about 0.5 sec. Add to this say another 0.2 for two extra network hops and the additional
response time to first display is about 3/4 of a second. This is a time shift all the way
down the set of results - most of which the user isn't aware of as they are beyond the
first 10 on screen, and the system allows interaction with those 10 while the rest are
getting their act together. So, under 1 second is added to response times which average
about 5 seconds. Of course, waiting for all the results adds this time to the slowest
results.
3) Most users seem happy to get things back faster and not worry too much about relevance
ranking. To combat the response time issue for users who require ranked results, the
incremental return can be set to show interfiled results as the later records come in and
rank within the ones displayed to the user. This can be disconcerting, but making sure
the UI doesn't lose track of the user's focus is helpful. Another option is to show that
"new results" are available, and let the user manually click to get them
incorporated - less intrusive, but an extra click!
General experience with the incremental displays shows that users are happiest with them when there is an obvious and clear reason for the new additions. The most accepted case is where the ranking criterion is price, and the user is always happy to see a cheaper item arrive. It really doesn't work well for titles sorted alphabetically - unless the user is looking for a specific title which should occur at the beginning of the list. And these examples illustrate the general point - that if the user is focused on specific items at the top of the list, then they are generally happy with an updating list, if they are more in "browse" mode, then the distraction of the updating list is just that - a distraction, if it is on screen.
Overall our experience from our partner's users is that they would rather see
things quickly than wait for relevance ranking. I suspect partly (can of worms
coming) because the existing ranking schemes don't make a lot of difference
(ducks quickly).
Peter
Peter Noerr
CTO, Museglobal
www.museglobal.com
-----Original Message-----
From: Code for Libraries [mailto:code4...@listserv.nd.edu] On Behalf Of
Walker, David
Sent: Tuesday, May 18, 2010 12:44 PM
To: CODE4LIB@LISTSERV.ND.EDU
Subject: Re: [CODE4LIB] OASIS SRU and CQL, access to most-current
drafts
in order to provide decent user experience you need to be
able to present some results "sooner" than others.
I would actually question whether this is really necessary.
A few years back, I did a big literature review on metasearch, as well
as a looked at a good number of usability studies that libraries did
with metasearch systems.
One thing that stood to me out was that the literature (written by
librarians and technologists) was very concerned about the slow search
times of metasearch, often seeing it as a deal-breaker.
And yet, in the usability studies, actual students and faculty were far
less concerned about the search times -- within reason, of course.
I thought the UC Santa Cruz study [1] summarized the point well: "Users
are willing to wait as long as they think that they will get useful
results. Their perceptions of time depend on this belief."
Trying to return the results of a metasearch quickly just for the sake
of returning them quickly I think introduces other problems (in terms
of relevance ranking and presentation) that do far more to negatively
impact the user experience. Just my opinion, of course.
--Dave
[1]
http://www.cdlib.org/services/d2d/metasearch/docs/core_ucsc_oct2004usab
ility.pdf
==================
David Walker
Library Web Services Manager
California State University
http://xerxes.calstate.edu
________________________________________
From: Code for Libraries [code4...@listserv.nd.edu] On Behalf Of Kuba
[skoc...@gmail.com]
Sent: Tuesday, May 18, 2010 9:57 AM
To: CODE4LIB@LISTSERV.ND.EDU
Subject: Re: [CODE4LIB] OASIS SRU and CQL, access to most-current
drafts
That is quite unfortunate, as we were looking at SRU 2.0 as a possible
candidate for the front-end protocol for Index Data's pazpar2. The
main problem with federate/broadcast/meta (however you want to call it
;) searching is that the back-end databases are scattered in different
locations or simply slow in their response times and in order to
provide decent user experience you need to be able to present some
results "sooner" than others. Waiting for the slowest database to
respond is usually not an option.
On Tue, May 18, 2010 at 5:24 PM, Ray Denenberg, Library of Congress
<r...@loc.gov> wrote:
On 18 May 2010 15:24, Ray Denenberg, Library of Congress
<r...@loc.gov>
wrote:
There is no synchronous operation in SRU.
Sorry, meant to say "no asynchronous .....
--Ray
--
Cheers,
Jakub
