Subject: entry definition

From: Henry Story <[email-masked]>
Date: Fri, 6 May 2005 18:46:59 +0200

Some have been clamoring for a good definition of an entry.
Here is one I have thought of recently.

An Atom Entry is a resource (identified by atom:id) whose  
representations
(atom:entry) describe the state of a web resource at a time
(the link alternate)

Any thoughts?

Henry

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From: "Bob Wyman" <[email-masked]>
Date: Fri, 6 May 2005 14:40:34 -0400

Henry Story wrote:
> representations (atom:entry) describe the state of a web resource
> at a time (the link alternate).

	I think that if this is not 100% "correct" then it is at least very
close to whatever correct actually is. 

		bob wyman

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From: David Powell <[email-masked]>
Date: Fri, 6 May 2005 21:24:41 +0100

> Any thoughts?

The entry's alternate link is optional isn't it?

-- 
Dave

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From: James Tauber <[email-masked]>
Date: Fri, 6 May 2005 22:53:52 -0400

In the case where there is an "alternate" I think this is correct,  
but it:

1. highlights the inaccuracy of the word "alternate"
2. doesn't address the case where there is no link alternate

James

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From: Henry Story <[email-masked]>
Date: Sat, 7 May 2005 14:35:42 +0200

> 2. doesn't address the case where there is no link alternate

I agree.

     My definition is making me wonder whether I should not in fact  
accept that
link alternate is a MUST.
     There may be ways of tweaking the definition which mean that I  
don't need to
come to that conclusion. Or perhaps one can think of entries without  
an alternate
as speaking about themselves?

     I agree also that the definition would make it more appropriate  
to have an
<about>...</about> node (or something similar) to highlight its  
importance.

     A good one sentence definition can help a lot in conveying the
complexities of something. As a result I may feel inclined to change  
my positions on
matters elsewhere to have them in accord with the definition, as  
opposed to making
the definition more complicated. It all depends. But I am pretty sure  
that a clear
definition of a core element of the spec would really help in  
spreading the understanding
of what we are doing.

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From: Graham <[email-masked]>
Date: Sun, 8 May 2005 15:35:06 +0100

> link alternate is a MUST.

Not really. There's no reason why the resource an Atom entry  
describes has to be visible online anywhere else.

>>> (atom:entry) describe the state of a web resource at a time

But in theory there's a one-to-one relationship between atom:id and  
the resource being described, and not between it and the link  
alternate (eg Alternate versions of several entries may all appear on  
the same webpage). This makes more sense to me:

     An Atom Entry is a resource whose representations (atom:entry)  
describe the state
     of a resource (identified by atom:id) at a time. [One or more  
alternate representations
     of that resource may also be available (link alternate)]

The part in square brackets isn't really part of the definition of an  
entry. The "at a time" not having an associated element bugs me. It's  
too late now, but we really should have had a "When was this snapshot  
taken?" date element.

Graham

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From: Henry Story <[email-masked]>
Date: Sun, 8 May 2005 21:38:43 +0200

> describes has to be visible online anywhere else.

yes.
I suggested that perhaps one could think of the atom entry as being  
about itself in that case.
Perhaps that is circular.

But perhaps not. Think of an entry id such as http://test.net/blog/ 
entry1
This could have two representations:
    -an atom entry representation
    -a simple html representation
One could think of the atom entry as being about the representation  
that would
be returned by fetching the same resource with a text/html mime type

> alternate (eg Alternate versions of several entries may all appear  
> on the same webpage). This makes more sense to me:
>
>     of a resource (identified by atom:id) at a time.

That is true by definition of the atom:entry representations being  
representations of the
atom:id resource. Representations of a resource are always  
descriptions of the resource they
are representations of. That's the whole point of the resource/ 
representation distinction.

So we agree that atom:entry representations are representations of  
the atom:id resource.

But what I thought interests us (humans) about these representations  
is that they contain information about the state of some other  
resource(s) (the link alternate). The entry is a collection of  
metadata (where the content can also be metadata), about the link  
alternate.
But perhaps I am wrong here. Perhaps an entry is just metadata (about  
the atom:content?). And
the time stamp atom:updated is the time at which all that metadata  
was changed (and so thought
to be correct).

> [One or more alternate representations
> The part in square brackets isn't really part of the definition of  
> an entry. The "at a time" not having an associated element bugs me.  
> It's too late now, but we really should have had a "When was this  
> snapshot taken?" date element.

I think there is in fact such a time element.
  - If the atom:id is a simple http url and can be dereferenced then  
the time of the
snapshot would be the time you fetched the representation.
  - if the atom:id is a undereferenceable uri such as uri:urn:...  
then it usually will come
   in another packet, eg a feed, which will have been fetched from  
the web. One could use that
   time stamp, if one fetches it oneself, or even better, one could  
use the atom:updated field
   of the feed.

I wonder if this exercise has been much help now.

Henry