In the returned data, the result section is empty, there are no error messages, and the correct URL is mentioned: <url execution-time="176" proxy="DEFAULT"><![CDATA[https://spreadsheets.google.com/feeds/cells/0Au659FdpCliwdG44Q2htMWJEQUxVQ3NfRlZUdlZaalE/od6/private/full]]></url>
Note: my final goal is to be able to query the Google spreadsheet like a database table. Using the Google access methods out-of-box, you can fetch - either individuals cells, but based on a query referencing column and row indices (i.e. 'A', 'B', ... '1', '2', ...) - either using a query referencing column names, but then you receive the data of the complete row in a single string (e.g. "en:christmas, fr:noel"), so then you must parse this string Based on the complete cell-based worksheet contents, YQL XML open table should be able to fetch the right data based on some clever XPath expression.
[balajin@visitbadfree-lm ~] $ curl -i 'https://spreadsheets.google.com/feeds/cells/0Au659FdpCliwdG44Q2htMWJEQUxVQ3NfRlZUdlZaalE/od6/private/full' HTTP/1.1 200 OK WWW-Authenticate: No credentials were included in your request. Date: Wed, 22 Sep 2010 17:52:49 GMT Expires: Wed, 22 Sep 2010 17:52:49 GMT Cache-Control: private, max-age=0 X-Content-Type-Options: nosniff X-Frame-Options: SAMEORIGIN X-XSS-Protection: 1; mode=block Content-Length: 0 Server: GSE Content-Type: text/html
See the above output. Looks like the URL is protected and is not returning any result. And since you must be signed into google, you are able to see results on the browser. I believe there is an option on the file upload akin to "Publish this as a file". Once you do that, you can use that URL which is public in the YQL query.
I'm going to work further on this and may report anything useful coming out.
Elsewhere, I read about using the CSV-publication format available for google spreadsheets, which can be queried by the CSV open table, but the disadvantage of that method is that the column names of the table must be declared in the query, and I cannot assume to know them upfront (or at least, I should query for them first).