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Bob Morris wrote:
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">Umm...there is a distinguishable class of data consumers,
namely <span style="font-style: italic;">applications</span>, and so a
distinguishable constituency whose burden is relevant, namely <span
style="font-style: italic;">
application writers.</span> Some applications may well be motivated to
query providers directly for a number of reasons, including:<br>
<ul>
<li>the data indexers currency policies may be unsuitable</li>
</ul>
</blockquote>
This equally applies to data providers. They may not index data in a
way the consumer requires. It may lag behind their own live data set
etc. <br>
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">
<ul>
<li>the data indexers may aggregate in undesirable ways [the
present model seems to be that indexer==portal, but I doubt that is
general]</li>
</ul>
</blockquote>
Ditto from point above. Data suppliers may index in undesirable ways
plus they might index heterogeneously - each supplier may be
undesirable in different ways - which would be a really big headache.
Is there anything to say this will cause
less of a burden when spread across many providers rather than few
indexers? If a thematic indexer doesn't do what is required then it may
be possible to get something changed. If 50 suppliers don't index
something correctly then it will no doubt take years to get any changes
affected - especially if they are all doing it wrong differently.
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">
<ul>
<li>the data indexers may index too promiscuously or not
promiscuously enough for the application's taste [this might be a
non-issue if there were a way for a machine to understand what exactly
the indexing strategy is and perhaps how to induce the indexer to alter
it, but that sounds hard]</li>
</ul>
</blockquote>
Again ditto. If providers are also indexers then any criticism of
problems with indexing has to apply to the suppliers but is magnified
by the number of suppliers.<br>
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">
<ul>
<li>portals, and maybe indexers---indeed, <span
style="font-style: italic;">any</span> processor of the data---can
intentionally or inadvertantly hide assumptions about how the data will
be used, making it unsuited for uses that don't meet these assumptions.
Put another way, it is probably difficult to insure that a
machine-enforceable contract is possible between aggregators and
applications that assures the application that records obtained from
the aggregator or identical to those available from the provider. I
think it is even a deep problem to have machine-understandable
"fitness for use" metadata that would allow a machine to understand
what fitness contract the aggregator is actually offering. </li>
</ul>
</blockquote>
I would assume that the aggregator is assembling metadata (in the sense
of things that can be searched on) rather than actual data. The
aggregator/indexer is really only providing a GUID discovery service.
The consumer can always retrieve the original objects from the data
supplier. The aggregator/indexer is only providing a match making
service.<br>
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">In general it should never be <span
style="font-style: italic;">harder</span> to query providers than
aggregators, especially if it is difficult for a machine to understand
what, if any, point of view the aggregator has imposed on the view they
offer of the aggregated data. <br>
<br>
</blockquote>
I don't believe this follows from your points above:<br>
<br>
I frequently go to websites and can't find what I want so I go to
Google and do a search restricting its scope to just that site. Indeed
Google provide this as a service - just embed a search box on your site
that passes the right parameters. In this situation it is definitely
easier to query the aggregator than the supplier. Indeed many sites
don't bother with providing search services other than Google (which is
the point I make precisely). The alternative is that every tin-pot
website has to have an implementation of the Google search algorithm
and indexes within it. (I appreciate that this is a human example but
it translates to a machine world. A data provider's metadata could
easily provide the location of web services to query it that are not
actually part of the provider itself. Indeed it could offer a list of
services. A neat place to do this would be in the WSDL returned by a
LSID Authority.) <br>
<br>
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">People are no doubt tired of hearing this from me, but my
position is always that modeling data consumers as humans is
dangerously constricting. Humans are too smart and readily deal with
lots of violations of the principle of least amazement, whereas
machines don't. In point of fact, except for those on paper, stone,
clay tablets and the like, there is no such thing as a database
accessed by a human. They all have software between the human and the
data provision service. From this I conclude that in your trinity
below, reduction of the burden on humans actually falls to the
applications, and so I think TAGs requirement is to reduce the burden
on application writers (including those of TDWG itself, but also all
others in the world) in <span style="font-style: italic;">their</span>
quest to reduce the burden on human data consumers. My intuition is
that this will lead to a different analysis than thinking about humans
as consumers, but at the moment I have no specific examples to offer. <br>
<br>
</blockquote>
I think this is a really good point and will take it forward. I hope to
start the TAG meeting with a discussion of Actors within our domain and
will attempt to differentiate client-human from client-machine within
this.<br>
<br>
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">A little more is interspersed below.<br>
<br>
<br>
<div><span class="gmail_quote">On 3/1/06, <b class="gmail_sendername">Roger
Hyam</b> <<a href="mailto:roger@tdwg.org">roger@tdwg.org</a>>
wrote:</span>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style="direction: ltr;">
<pre>This is a little more of a controversial question that has been suggested:
"Why should data providers supply search and query services?"
</pre>
<ul>
<li>We have many potential data providers (potentially every
collection and institution).</li>
<li>We have many potential data consumers (potentially every
researcher with a laptop).</li>
<li>We have a few potential data indexers (GBIF, ORBIS , etc +
others
to come).</li>
</ul>
<pre>The implementation burden should therefore be:
</pre>
<ul>
<li>Light for the providers - who's role is to conserve data and
physical objects.</li>
<li>Light for the consumer - who's role is to do research not
mess
with data handling.<br>
</li>
<li>Heavy for the indexers - who's core business is making the
data
accessible.</li>
</ul>
Data providers should give the objects they curate GUIDs. This is
important because it stamps their ownership (and responsibility) on
that piece of data. They then need to run an LSID service that serves
the
(meta)data for the objects they own. <b>There work should stop at this
point!</b>
They should not have to implement search and query services. They
should not anticipate what people will require by way of data access -
that is a separate function.<br>
<br>
Data consumers should be able to access indexing services that pool
information from multiple data providers. They should not have to run
federated queries across multiple data providers or have to discover
providers as this is complex and
difficult (though they may want to browse round data providers like
they would browse links on web pages). Once they have retrieved the
GUIDs of the objects they are interested
in from the indexers they may want to call the data providers for more
detailed information.<br>
<br>
Data indexers should crawl the data exposed by the providers and index
them in thematic ways. e.g. provide geographic or taxon focused
services. This is a complex job as it involves doing clever, innovative
things with data and optimization of searches etc.<br>
<br>
Currently we are trying to make every data provider support searching
and querying when the consumers aren't really interested in querying or
searching individual providers - they want to search thematically
across
providers.</div>
</blockquote>
<div><br>
Restated, this sentence may fall in my class of questions forbidden to
software architects, namely that class of questions that begin with
the words "Why would anybody ever want to ..." <br>
</div>
</div>
</blockquote>
I should restate it "What is the use case that indicates the system
should support this behavior?"<br>
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">
<div><br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style="direction: ltr;">If a big data provider wants to
provide search and query then
they can set themselves up as both a provider and an
indexer - which is more or less what everyone is forced to do now - but
the functions are separate.<br>
<br>
Data providers would have to implement a little more than just an LSID
resolver services for this to work. They would need to provide a single
web service
method (URL call) that allowed indexers to get lists of LSIDs they hold
that have had their (meta)data modified since a certain date but this
would be a relatively simple thing compared with providing arbitrary
query facilities.<br>
<br>
I believe (though I haven't done a thorough analysis of log data ) that
this is more or less the situation now. Data providers implement
complete DiGIR or BioCASE protocols but are only queried in a limited
way by portal engines. Consumers go directly to portals for their data
discovery. So why implement full search and query at the data provider
nodes of the network (possibly the hardest thing we have to do) when it
may not be used?<br>
<br>
This may be controversial. What do you think?</div>
</blockquote>
<div><br>
<br>
I'm not sure about controversial, but I am pretty sure that what you
are pointing at is a warehouse model. I don't know if I am prepared to
agree that all possible present and future concerns of TDWG can be
answered by data warehouses. In particular, if you analyse log data of
a warehouse, it won't be too surprising if the conclusion is that users
are behaving as though they mainly need a warehouse. [To data consumers
a warehouse and a portal are indistinguishable. I think.] <br>
<br>
</div>
</div>
</blockquote>
This is why I use the term 'indexer' rather than aggregator. The
analogy with web search engines is a good one. Basically we have to
implement aggregated-indexes for key data (although federated searching
by crawling all the providers is theoretically possible if you are not
in a hurry) the question I raise is whether we also need to implement
querying in every provider.<br>
<br>
<blockquote
cite="mid16957b040603021857p56e9075fvc0fbb169b669c8fd@mail.gmail.com"
type="cite">
<div>
<div>Bob Morris<br>
</div>
<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style="direction: ltr;">Roger<br>
<br>
<pre cols="72">--
-------------------------------------
Roger Hyam
Technical Architect
Taxonomic Databases Working Group
-------------------------------------
<a href="http://www.tdwg.org" target="_blank"
onclick="return top.js.OpenExtLink(window,event,this)">
http://www.tdwg.org</a>
<a href="mailto:roger@tdwg.org" target="_blank"
onclick="return top.js.OpenExtLink(window,event,this)">roger@tdwg.org</a>
+44 1578 722782
-------------------------------------
</pre>
</div>
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</blockquote>
</div>
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</blockquote>
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