On 8 May 2005, at 16:35, Graham wrote:
On 7 May 2005, at 1:35 pm, Henry Story wrote:My definition is making me wonder whether I should not in fact accept that
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.
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
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)
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.
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 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.
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
Graham
