At 12:25 AM 8/16/00 -0600, Stuart G. Poss wrote:

Bryan Heidorn wrote:

...

What I am concerned about with the revision number is easing processing for www spiders and for composite documents created from lower level documents/treatments. www spiders search the network for new documents to index. If the documents are dynamically created "on demand", they are in

some

...

way different every time the spider looks, if nothing else because the "creation date" will change to always be now. We need something more stable like editorial date... the last time a qualified human said the record was

OK.

Yes. Each "atomic element" must have a "date last modified [by authority]" attribute for the reason you suggest.

However, would not the spec also need to require that the "spider", or specifically those processing instructions that define the "behavior" or

result

set produced by the spider or other collation [transformation] programs (methods), also leave a distinguishing revision number in the document so

that

one can determine what specific method was used? One might expect different behaviors even for slight changes to the processing (compilation) code

used to

assemble the consitutent [atomic] elements of the document to influence the document content.

I was thinking the document type definition would specify a method for generating a field. Kevin had an example of calculating a mean or something like that. That does mean that there need to be a set of predefined methods for value calculation and collection but I do not think that we need to be exhaustive in the spec. The spec can just say that you should identify your method. If it is all object oriented as Bob suggests it might be real executable code. I think that is too much to ask for the first rev of the spec but it should be an option. As Stuart suggests, the resulting value generated by a method at a particular time needs to be tagged with information about when and how it was generated. The attribution fields might do part of that.

Even though there may be transient lack of availability of some distributed resources (perhaps due to network failure, loss of a particular server,

server

load, etc.] , the behavior of the "spider" also could influence the document content [atomic element inclusion], albeit independently. This would be an

issue

for "higher level" associations (documents) that are created by automatically assembling other "documents" that are themselves constructed from "atomic elements". Consequently, requiring the "spider" [read element inclusion processing instructions] to leave an identifying mark in the document would provide an ability to distinguish the source of the potential differences in

the

final dynamic document.

ditto

...

The same problem exists for higher level taxon descriptions that are

created

...

from lower level descriptions. There was a short thread about this a while

ago

...

on this list. A good feature of dynamic creation of the descriptions is

that

...

when a low level detail changes the higher level summary information also automatically changes. The "oops, that specimen was actually a different species" syndrome, may cause a character state recording some value to

change

...

(because the outlier was recognized as another species.) We do not want to have to recalculate and verify all atomic facts whenever someone looks at a high level description.

Yes, I fully agree that the lower [atomic] level of detail must force changes

at

higher more associative/inclusive levels precisely for the reason you

suggest.

However, within an environment where the data may be distributed there may be sources of error that may be generated when "key" atomic elements are not

found

(server load to great, network failure, etc) or perhaps only older versions

can

be located (only mirrors available, unflushed cache, etc). Consequently, to assess the logic needed to [possibly further] process or interpret a

document's

contents would it not be useful to also have a means to pass knowledge of

what

methods were used to assemble the document? Presumably, the behaviors of

the

processing instructions (document generating methods) will influence the circumstances under which some kinds of atomic element processing

instructions

(methods) will fail while others may succeed, say in making subsequent

changes

"automatically" or "recognizing" the existence of another species.

Don't we need a spec that includes [requires?] a means to pass knowledge

about

the kinds of associations that were made to generate the document, as well as

the

lower level "atomic elements"and their attribution, if we are to avoid recalculation to fundamental atomic level at each stage in the transformation (document building) process? If documents were characterized in XML, this

could

make it much easier to chain XML transformations by faciliating the

recognition

of what order of transformations were permissible. This could also greatly simplify the modification of processor (method) behavior and the development/maintenance of efficient interprocess communication. A document

that

was validated by successfully being transformed at one lower level of

processing

to another by a given method, would not require revalidation at these "lower levels" when being transformed to the next "higher" level by another method. Presumably, such tags could be scattered at widely different levels within

the

document, indicating scope of the document over which specific

transformations

were relevant.

Right. This is complex. Any CS doctoral students out there looking for a dissertation? Just kidding! It is not that bad. Well, if we make simplifying assumptions it is not that bad. For rev 1.0 we should skip it but I can think of an easy case to test. We could include a common name list in the butterfly records from itis*ca. That list could be manually generated at first. By "manually", I mean have the contributor search itis and type the results by hand into the treatment. Later we can have the system query itis for XML that can be inserted directly (or transformed first) into the treatment, on-the-fly. We'll see how the method tracking issue shakes out on the real example.

These issues are separate from the kinds of errors that may result when a

method

encounters "atomic elements" that are internally inconsistent, within a distributed processing environment. So far we've avoided how to handle this separate issue within the spec. I don't have an answer except perhaps simply requiring everyone to agree :-) or specifying the kinds of errors that should

be

generated under such conditions.

Perhaps we should just report processing errors somewhere. All calculated fields have comment fields already. Perhaps there should be exception fields too that in most cases will be empty. Again, this is a bell or whistle that is not needed to get "something" running.

Perhaps others may suggest a better/alternate approach to address these

aspects

of dynamic document generation/transformation within the spec.

Bryan -- -------------------------------------------------------------------- P. Bryan Heidorn Graduate School of Library and Information Science pheidorn@uiuc.edu University of Illinois at Urbana-Champaign (V)217/ 244-7792 501 East Daniel St., Champaign, IL 61820-6212 (F)217/ 244-3302 http://alexia.lis.uiuc.edu/~heidorn