Subject: Re: Posted PaceEntryOrder (was Entry order)

From: "David Powell" <[email-masked]>
Date: Sat, 5 Feb 2005 10:20:15 -0000

>(I.e., I could come up with the UseLexicalOrdering extension, and 
   >require processors to understand it to use the feed, assuming our 
   >extensibility model supports that, which I very much hope it will).
   
Ok, well I am assuming that we won’t have MustUnderstand extensions, therefore all extensions must be just informative.

   >My preference would be something like
   >
   >This specification assigns no significance to the order of atom:entry 
   >elements within an Atom Feed Document. Atom Processors MAY present 
   >entries in any order, unless a specific ordering is required by an 
   >extension.
   >

Given a model of only informative metadata extensions this wouldn't be valid, unless the spec said that the order was significant, then it would be acceptable to communcate a preferred display order using extensions.

The question is basically, if I have a database does it need to preserve the sequence number of the entry within a document?  Display order is a different matter, but for the option of lexical order, then the answer would need to be yes, but I don't think it would be worth it.

-- 
Dave

---

From: Henry Story <[email-masked]>
Date: Sat, 5 Feb 2005 13:38:34 +0100

On 5 Feb 2005, at 11:20, David Powell wrote:
> Given a model of only informative metadata extensions this wouldn't be 
> valid, unless the spec said that the order was significant, then it 
> would be acceptable to communcate a preferred display order using 
> extensions.
>
> The question is basically, if I have a database does it need to 
> preserve the sequence number of the entry within a document?

You put this in terms of databases and I put the question in terms of 
graphs (which if you
have an rdf database to store your triples comes to the same thing).

And my feeling is here that we should not have to keep the sequence 
numbers of the
order of the entries in the document.

Perhaps this is what Roy Fielding is getting at when he speaks of there 
being confusion
on this list between the data model and the interaction model. It is 
important for
clients when they ask for a sequence of entries to know what the order 
those entries
are coming in. This can save them a lot of processing time. But it 
should not be part
of the syntax to specify a preferred order of the entries.

>  Display order is a different matter, but for the option of lexical 
> order, then the answer would need to be yes, but I don't think it 
> would be worth it.

Display order on the client will also completely depend on what the 
client is trying to
do. If the client is just interested in archiving all the entries, then 
any new feed
be it an old one or a new one will be of interest: it will just be 
added to the database.
If the client is interested in displaying the changes in a gui, this 
again may be completely up to the user. Some users may want only to see 
entries that they have read
that have changed, as this may show a change of position of interest to 
them.

Henry Story

---

From: Mark Nottingham <[email-masked]>
Date: Sat, 5 Feb 2005 09:48:43 -0800

> order of the entries in the document.

Very well said, with emphasis on "have to"; they shouldn't be 
prohibited from doing so if they want to (and I don't think you're 
saying otherwise).

> do. If the client is just interested in archiving all the entries, 
> then any new feed

+1

--
Mark Nottingham     http://www.mnot.net/

---

From: Henry Story <[email-masked]>
Date: Sat, 5 Feb 2005 19:12:22 +0100

> prohibited from doing so if they want to (and I don't think you're 

yes, but perhaps if these were to be kept in the database they should
not be saved as a direct property of the entry, but as a relation that 
the entry has to an event of document fetching.

I am thinking here about the parallel with search engine results.
The results you get from a search engine will be ordered in some
way. This is inevitable. But one should be careful not to think that
generally the results have any intrinsic meaning. Certainly not
intrinsic in the sense that these would usefully be thought of
as being properties of the web pages themselves. They are rather
a factual statement about an order given by the search engine when
you made a request at a certain time.

Continuing along this line of thought, if you made a request to
your favorite search engine to return its results in last changed
order (and perhaps narrowed your request down to a specific site)
then the order of the results could help you come to conclusions
much faster. If could save you for example having to search
through all the results if you were only looking for entries that
had changed in the last day. Once you reached results that had
changed before that, you would be sure that all other results were
no longer relevant.

I think this is probably what Roy fielding meant recently when he
spoke about the difference between the model and the interaction
model. In any case this should be something that one specifies at
the protocol level.

Henry Story

>> be it an old one or a new one will be of interest: it will just be 

Cool sometimes I also get +1 :-)