Subject: Closure on Extensibility & RDF

From: Tim Bray <[email-masked]>
Date: Sat, 08 Jan 2005 10:49:14 -0800

[On behalf of Paul and myself:]

The opinion has been forcefully expressed that Atom should adopt an 
extensibility framework based partly or wholly, directly or indirectly, 
on RDF.  This idea is not unreasonable on the face of it.  Thus, the 
time has now come to put this into a concrete proposal.  Since we've 
talking about it for months, this shouldn't take long.

Would the advocates of this view please, by Monday January 17th, bring 
the WG a proposal for its consideration.  This could take one of these 
forms:

- A Pace proposing extensibility-framework changes to the language of 
the format draft.  (Rob/Joe, any chance of getting that -04 draft I 
know you're working on published Real Soon Now as a basis?)
- A new Internet-Draft that co-exists with the existing Atom drafts 
that describes an extensibility framework.
- Both.

Note that if you do a Pace and it fails to obtain quick consensus, the 
ideas may fall by the wayside; on the other hand, if you do an I-D this 
may find a life of its own and wind its way to RFC-hood even if people 
in the Atom community remain unconvinced that they need it.  Also, work 
on an I-D would be free of the distraction of Paul and I snarling at 
everyone to finish it up and ship it right now :)

On the other hand, if the extensibility framework requires only a few 
simple additions and/or changes to the existing drafts, and there's a 
chance the WG will be OK with them, then that's probably a much better 
way to go.

In any case, we've invested enough time arguing in the abstract.  
Discussions on this subject which are not framed in terms of specific 
language in specific documents will be ruled out of order by the 
co-chairs starting Monday January 17th.

  -Tim

---

From: Henry Story <[email-masked]>
Date: Sat, 8 Jan 2005 20:33:20 +0100

Here is one suggestion I was thinking of to move along, quickly and 
seamlessly I hope.

   1. Atom will have an associated machine readable OWL document that 
defines each
    of the objects and properties described in the Atom syntax spec, 
with language
    that mirrors that of the spec.
     1.1 The IETF document is the final arbiter of any disputes

   2. The Atom-OWL document will be placed at the namespace location of 
the Atom spec.
     2.1 it will be retrievable in full by requesting that http location 
using the application/rdf+owl mime type
     2.2 any of the atom properties or Entities definition will be 
retrievable by
requesting the url of those entities in a web browser
     2.3 a link to the atom-owl document will be placed from the IETF 
spec to the
         atom-owl document, specifying that a machine readable version 
of the spec
         is available at that location.
     2.4 And vice versa the Atom-owl document will point to the IETF 
spec as the
         final arbiter of the meaning of the Atom-OWL document

   3. Evolution of the Atom-OWL and Atom IETF specs
     3.1 The aim is that any IETF Atom conformant document, be an RDF 
document
         as described by something like the transformation in [1]
     3.1 during the evolution of the atom OWL development, the atom-owl 
document
        will be under the obligation to do anything it can within the 
syntax
        allowed by rdf and owl to map precisely the IETF document
     3.2 If it is absolutely impossible for some aspect of atom-owl to 
map the
         IETF document, this should give some cause to think of revising 
the IETF
         spec so that such a mapping does become possible. This should 
be rare.

   4. An Atom extended document is an Atom document with additional name 
spaced
     elements the whole of which can be mapped into an RDF graph.

Henry Story

[1] http://www.imc.org/atom-syntax/mail-archive/msg11850.html

On 8 Jan 2005, at 19:49, Tim Bray wrote:

> extensibility framework based partly or wholly, directly or 
> indirectly, on RDF.  This idea is not unreasonable on the face of it.  
> Thus, the time has now come to put this into a concrete proposal.  
> Since we've talking about it for months, this shouldn't take long.
>
> ideas may fall by the wayside; on the other hand, if you do an I-D 
> this may find a life of its own and wind its way to RFC-hood even if 
> people in the Atom community remain unconvinced that they need it.  
> Also, work on an I-D would be free of the distraction of Paul and I 
> snarling at everyone to finish it up and ship it right now :)
>

---

From: "Jeremy Gray" <[email-masked]>
Date: Sat, 8 Jan 2005 12:02:13 -0800

> -----Original Message-----
> From: [email-masked]
[mailto:[email-masked]] On Behalf Of Tim Bray
> Sent: Saturday, January 08, 2005 10:49 AM
> To: 'Atom WG'
> Subject: Closure on Extensibility & RDF
> 

Hehe. I finally post a long-winded message on the subject and then within
moments I receive this in my inbox. I'll definitely give Tim's message a
think, along with the replies to it, over the weekend. Have a good weekend
everyone.

Jeremy

PS - Henry, Danny, Bill/Bill, et al - I know its been a while since I've
been actively involved, but now looks like it would definitely be the right
time, if any. If I can be of any assistance, whether in looking over draft
text and/or playing devil's advocate in any conference calls, email threads,
IRC chats, whatever, please feel free to get in touch. In the meantime, I'm
going to think about a few extensibility experiments I have in mind, and
will let you know if anything interesting comes of them.

---

From: Paul Hoffman / IMC <[email-masked]>
Date: Sat, 8 Jan 2005 12:50:42 -0800

>Here is one suggestion I was thinking of to move along, quickly and 

All that seems fine, but your list is neither a Pace nor an Internet 
draft, and is therefore not in line with what Tim and I asked for. 
Given that you talk about an "IETF document", I am assuming that you 
intend to write the Internet Draft, yes?

--Paul Hoffman, Director
--Internet Mail Consortium

---

From: Henry Story <[email-masked]>
Date: Sat, 8 Jan 2005 22:54:28 +0100

The IETF document I mentioned is the one this mailing list is working 
on developing. The four points I listed are starting points for a 
couple of small additions to the Atom IETF document and their relation 
to a to be written OWL Ontology. There are I am sure people more 
familiar with the ins and outs of this standards process that will know 
how to turn that general idea into more specific and acceptable 
proposals.

Henry

---

From: Paul Hoffman / IMC <[email-masked]>
Date: Sat, 8 Jan 2005 14:35:21 -0800

At 10:54 PM +0100 1/8/05, Henry Story wrote:
>The IETF document I mentioned is the one this mailing list is 
>working on developing.

Then you didn't understand Tim's message. He meant a *new* Internet 
draft, not a change to the current draft (unless the change is a few 
sentences). From your list of changes, it doesn't seem like it is 
just a few sentences, so you need to submit a separate Internet 
Draft, initially as an individual submission. If the WG agrees that 
it should be a WG work item, it will change into one; otherwise, you 
can pursue it as an individual document, probably still discussing it 
on this mailing list.

>  The four points I listed are starting points for a couple of small 
>additions to the Atom IETF document and their relation to a to be 
>written OWL Ontology. There are I am sure people more familiar with 
>the ins and outs of this standards process that will know how to 
>turn that general idea into more specific and acceptable proposals.

See Tim's message. You do this by creating either a detailed Pace or 
a complete Internet Draft.

--Paul Hoffman, Director

---

From: Henry Story <[email-masked]>
Date: Sun, 9 Jan 2005 00:06:27 +0100

The "internet draft" I want to propose is an OWL document. I can get 
this out tomorrow. It will essentially say everything the current Atom 
OWL spec says, but in machine readable form.

All that is required then is that the Atom IETF document this working 
group is working on have some language describing its relation to the 
OWL document. This need not be a very big change to the current 
document. I believe it could be done in a few sentences taking my first 
proposal as a guide. If anyone has some good ideas on where it would be 
best to change the language, please help me along and write that out. I 
can do with all the help out there :-)

Understand that all I am proposing is a machine readable rewriting of 
what the current Atom spec says. That is most of what there is to it. 
The rest is just asking for a little good will.

Yours sincerely,

Henry Story
http://bblfish.net/blog/

On 8 Jan 2005, at 23:35, Paul Hoffman / IMC wrote:

>> on developing.
> sentences). From your list of changes, it doesn't seem like it is just 
> a few sentences, so you need to submit a separate Internet Draft, 
> initially as an individual submission. If the WG agrees that it should 
> be a WG work item, it will change into one; otherwise, you can pursue 
> it as an individual document, probably still discussing it on this 
> mailing list.
>
>> the ins and outs of this standards process that will know how to turn 
>> that general idea into more specific and acceptable proposals.
>
> See Tim's message. You do this by creating either a detailed Pace or a 
> complete Internet Draft.
>
> --Paul Hoffman, Director

---

From: Henry Story <[email-masked]>
Date: Sun, 9 Jan 2005 00:15:38 +0100

On 9 Jan 2005, at 00:06, Henry Story wrote:

> OWL spec says,

Sorry it is past midnight here at I am typing a little fast.
I meant "It will essentially say everything the current Atom spec[1]  
says,"

[1]  
http://ietf.levkowetz.com/drafts/atompub/format/draft-ietf-atompub- 
format-03.txt

>  but in machine readable form.
>
> document. I believe it could be done in a few sentences taking my  
> first proposal as a guide. If anyone has some good ideas on where it  
> would be best to change the language, please help me along and write  
> that out. I can do with all the help out there :-)
>

---

From: Paul Hoffman / IMC <[email-masked]>
Date: Sat, 8 Jan 2005 15:25:17 -0800

At 12:06 AM +0100 1/9/05, Henry Story wrote:
>this out tomorrow. It will essentially say everything the current 
>Atom OWL spec says, but in machine readable form.

An OWL document is not an Internet Draft. If you cannot create an 
Internet Draft, please find someone who agrees with your desires to 
help you.

>All that is required then is that the Atom IETF document this 
>working group is working on have some language describing its 
>relation to the OWL document.

That should be included in your Internet Draft.

>  This need not be a very big change to the current document.

That remains to be seen. The best way we can see it is in your 
Internet Draft. Clearly, if it is a small change and the WG wants to 
use it, it can be folded into the main document before we send it to 
the IETF.

>  I believe it could be done in a few sentences taking my first 
>proposal as a guide.

Great! Let's see them.

>  If anyone has some good ideas on where it would be best to change 
>the language, please help me along and write that out.

That is actually the least important point in your proposal, and the 
easiest to take care of late in the process if the WG agrees to the 
incorporation. If the WG doesn't agree to the incorporation, it isn't 
needed at all in your Internet Draft.

>I can do with all the help out there :-)

So can we all...

>Understand that all I am proposing is a machine readable rewriting 
>of what the current Atom spec says.

In order for us to verify that statement, we need to see the 
rewriting, and we need to hear from a few people who understand OWL 
saying "yup, that exactly matches what is in the format draft".

>  That is most of what there is to it. The rest is just asking for a 
>little good will.

Fully disagree. The rest is the WG coming to consensus on whether or 
not we want this as part of the baseline spec. Given this WG's 
propensity to disagree about most things XML and RDF, assuming that 
will come easily is not based on even a casual reading of the mailing 
list.

--Paul Hoffman, Director

---

From: Henry Story <[email-masked]>
Date: Sun, 9 Jan 2005 00:48:33 +0100

I can't do everything simultaneously. Tomorrow I will give you a first 
version of an OWL document that will map the current atom spec. Can you 
give me the current namespace for the draft atom spec I am supposed to 
be working to? This is so the atom OWL document can describe the 
properties of the draft atom spec.

The url of the location of the directory of the draft spec will 
probably do.
Then I can define the properties of atom:content using the full url say

  http://purl.org/atom/#content

When someone clicks on that link with a browser that asks for the 
content as text/simple they will get the current atom draft spec. When 
they ask for it using the mime type application/rdf+owl they will get 
the document I will present you tomorrow.

With this document at hand it will be a lot easier to explain the 
relation between the spec and the OWL document, either in the current 
atom spec, or if you really insist, in a separate Draft. That will be 
machine interpretable xml, ie: running code.

Good night,

	Henry Story

On 9 Jan 2005, at 00:25, Paul Hoffman / IMC wrote:

>> OWL document.
>> what the current Atom spec says.
>

---

From: Henry Story <[email-masked]>
Date: Sun, 9 Jan 2005 18:14:37 +0100

Attached is the closest I could get today in writing the Atom ontology. 
There is an N3 and RDF version of the OWL Ontology. For a nice and 
easily understood reading of the data you can have a look at these 
files using Protégé [1]. Of course they can also be read with a simple 
text or xml editor.

These files illustrate the relationship between the ontology and Atom. 
As you can see I describe the meaning of each property simply by 
referring to the IETF Atom chapters. The Atom IETF document is 
therefore the final arbiter of the meaning of these terms.

This exercise has made me aware of the following problem with the spec: 
there are two title properties that are not quite the same: the title 
attribute of the link points to a simple string whereas the title of 
the Head and Entry are more complex structures.

As far as the modeling goes I am having difficulty modeling the 
following elements in Protégé:
	- the Atom TEXT element seems to be a union of three different literal 
types:
         + string
         + xml
         + encoded html
       is it possible for a property to have three different literals 
types?
     - I am not sure how to model the Generator element

The whole thing will just make a lot of sense when looked at in 
Protégé. It is written in Java and so is available on all platforms.

Clearly there is ironing out to be done, as I may have missed out a few 
properties.

This ontology should enable us to get very close to our aim which is to 
have a well formed Atom file be a file that is an rdf graph that uses 
the above ontology.

If we can get the ontology to be a formalization of the spec, then it 
will be very simple to explain how to extend Atom.

Henry Story

[1] http://protege.stanford.edu/