Thomas Broyer wrote:
2006/10/9, Andreas Sewe:
But while the draft states that "[t]hese [feed] types are complementary"
(section 1), but is unfortunately silent on how precisely the three
different types can be used together.
Here are a few questions I still have:
- Is it possible that an Archived Feed Document is marked as complete?
By definition, an Archived Feed is a set of Feed Documents, and an
Archive Document is a Feed Document within that set. It cannot be
"complete", unless it is the only one in the set, and therefore
represents the whole Archived Feed as a single Feed Document. It's
"current" link should then point to itself (i.e. the same as the
"self" link).
Thank you for the clarification; I did not get my terminology straight.
But it would be desirable, IMHO, to be able to link to archived, older
versions of a complete feed from within the current complete feed document.
Say, a feed document contains this month's Top Ten. Wouldn't it be nice
if the feed document could link to September's Top Ten, in case anybody
is interested in all the recent Top Ten lists? And linking to archived
feed documents is precisely what "prev-archive" and "next-archive" are
for. So why can't I use them in conjunction with complete feeds?
- Is it possible that a Paged Feed's pages (i.e., its feed documents)
are marked as complete?
No. By definition, a Complete Feed is a single Feed Document.
See:
2. Complete Feeds
A complete feed is a feed document that contains all of the entries
of a logical feed; any entry not actually in the feed document SHOULD
NOT be considered to be part of that feed.
This is the same reason as to why archived feeds can't be complete. But,
as I argued above, making an archive of complete feed documents
available ought to be possible with archived feeds, too.
Now, in contrast to archived feeds, paged feeds serve a different
purpose: they allow a logical feed to be divided into more easily
digestible pages. (See the APP draft: "A naive client such as a web
spider or web browser could be overwhelmed if the response to a GET
contained every entry in the Collection, and the server would waste
large amounts of bandwidth and processing time on clients unable to
handle the response.")
And I can't think of a reason why complete feeds are per se small enough
to be served without problems as a single document. Granted, the above
Top Ten list example contains, in all likelihood, only ten entries, but
what about Top 100s, the Supercomputing Top 500, etc.?
If you accept the usefulness of complete paged or archive feeds for a
moment, you will see that "completeness" should extend from one page to
the next (or previous), but not from one archive document to another;
each archive document is considered complete in its own right.
- Is it possible to serve a single, possibly large Archive Document as
multiple pages?
Not sure what you're talking about...
>
Do you mean a Logical Feed would be split into "stable subsets", each
such subset split into "unstable" Feed Documents?
In this case, as each document is not "stable", it's a Paged Feed, not
an Archived Feed, even if the subset of entries from within 2 Feed
Documents form a "stable subset".
If every Feed Document is "stable", then you have an Archived Feed an
dyou can link Feed Documents to each others using next-archive and
prev-archive.
This was more or less what I was getting at, and while I recognize the
issue of stability, being able to page an archive document does make
sense if you follow the above analysis: 1) archival of complete feeds is
useful (each archive document will be marked as complete) and 2) even
complete feeds may need to be paged (each complete archive document
might be served as several pages).
Putting it all together this leads to a variant of the diagram in my
previous mail:
Compl. Archive Document 1 -\ Compl. Archive Document 2
========================= \ =========================
Page 1.1 -next-> Page 1.2 \-prev-archive-> Page 1.1 -next-> Page 1.2
Here Archive Document 1 contains, say, last month's Top 100 as a
complete archive document split into two pages of 50 entries each. It
then links, via "prev-archive", to August's Top 100 which is again split
in two.
Does this explanation make sense?
I am aware, now, that this is not what the current draft says, since the
three types of feed (complete, paged, and archived feed) can't be
combined in *any* way, even though the draft's introduction claims that
"[t]hese types are complementary". But at least some of the additional
expressiveness offered by the combination of complete with either paged
or archive feeds would be nice to have -- even though it adds some minor
complexities.
Regards,
Andreas Sewe
