[eml-dev] Recommendations for reporting file access errors to software agents

[Wade Sheldon]

Oops, I incorrectly included a "correct" url as an example. Here's what I intended:

Invalid EML distribution URL (agent client):
http://gce-lter.marsci.uga.edu/lter/asp/db/send_file.asp?accession=PLT-GCED-0409&filename=PLT-GCED-0409_1_2.TXT&name=metacat-user&email=none&affiliation=LNO&notify=0

Note that if you paste this into a web browser after you have created a 
temporary session by logging in to download some other file (or trying the 
interactive link), or execute this url twice, it will switch to interactive 
mode. That's expected behavior.

--Wade



Wade Sheldon wrote:
> Matt and all,
> 
> What type of error message (content and formatting) do you think should be
> returned to a software agent that tries to retrieve an inaccessible ASCII data
> table referenced in an EML document? For instance, if a particular version of a
> data set has been taken offline due to the discovery of major errors, how should 
> the file access error be communicated to Kepler or some other Metacat/EML-savvy 
> software agent (i.e. when they try to retrieve the old file based on a legacy 
> EML document that hasn't been re-synced yet)?
> 
> The reason I'm asking is that I've been revising the GCE data distribution web
> application to support stored cookies and more gracefully handle requests for
> outdated or offline files, and I'd like to provide optimal support for both
> interactive web clients and agents. I am currently using http and session
> characteristics to distinguish these client types, and bouncing web clients to a
> "contact the IM for assistance" web form on errors and returning a simple text 
> message to agents, e.g. "Error: PLT-GCED-0409_1_2.TXT was not found on the 
> GCE-LTER server (contact the GCE Information Manager <gcelter at uga.edu> for 
> assistance)". If there is a common structured error message format (xml or text) 
> supported by Kepler or other SEEK tools, though, I will use that instead.
> 
> Here are examples of what I'm doing now for invalid versions of data set tables 
> (invalid data set accessions or missing files are handled similarly with 
> different messages):
> 
> Invalid EML distribution URL (agent client):
> http://gce-lter.marsci.uga.edu/lter/asp/db/send_file.asp?accession=PLT-GCED-0409&filename=PLT-GCED-0409_1_1.TXT&name=metacat-user&email=none&affiliation=LNO&notify=0
> 
> Invalid EML distribution URL (interactive client, using web session/cookie/login):
> http://gce-lter.marsci.uga.edu/lter/asp/db/send_file.asp?accession=PLT-GCED-0409&filename=PLT-GCED-0409_1_2.TXT
> 
> 
> One a related note, I've been archiving outdated but otherwise valid data sets
> (e.g. those that have been updated to add an attribute or records) so that they
> can be retrieved by URLs in legacy EML docs. However, not communicating the fact
> that a more recent version of a data table is available seems to be a disservice
> to users. Do you think it would be preferable to return an error or message if a 
> more recent version of a data set exists, or just keep returning the old version 
> as requested (if not taken offline) until the metadata is re-synced?
> 
> We are currently finalizing the "EML Best Practices for LTER Sites" document for 
> general distribution, so if there is a consensus on these issues I'll add 
> recommendations to the eml/dataset/dataTable/physical/distribution/online/url 
> section.
> 
> Thanks.
> 
> Wade Sheldon
> GCE-LTER Information Manager
> 
> 
> ____________________________________
> 
> Wade M. Sheldon
> GCE-LTER Information Manager/SIMO Database Administrator
> School of Marine Programs
> University of Georgia
> Athens, GA 30602-3636
> Email: sheldon at uga.edu
> WWW: http://gce-lter.marsci.uga.edu/lter/bios/wsheldon.htm
> 
> _______________________________________________
> Eml-dev mailing list
> Eml-dev at ecoinformatics.org
> http://mercury.nceas.ucsb.edu/ecoinformatics/mailman/listinfo/eml-dev

-- 
____________________________________

Wade M. Sheldon
GCE-LTER Information Manager/SIMO Database Administrator
School of Marine Programs
University of Georgia
Athens, GA 30602-3636
Email: sheldon at uga.edu
WWW: http://gce-lter.marsci.uga.edu/lter/bios/wsheldon.htm