Re: Kickstarting the Provenance Access and Query Task Force

Olaf Hartig wrote:
 > Proposal 1: The final report [2] of the W3C provenance incubator group contains
 > a section on "Provenance in Web Architecture", Sec.6. The PAQ TF uses this
 > section as foundation for the draft that we want to have for the F2F meeting.
 > By "foundation" I mean as a first incomplete (and inofficial) draft.

-- 
http://www.w3.org/2005/Incubator/prov/XGR-prov-20101214/#Provenance_in_Web_Architecture


...

Short answer:

-- http://www.w3.org/TR/powder-dr/#assoc-linking

...

Longer answer:

I've just re-reviewed the Web Architecture section from Prov XG, and have some 
possible concerns with it.


1. The Web architecture considerations stated by the XG are veru narrowly stated 
in terms of a web of documents served by HTTP.  HTTP may be the main Web 
protocol but it's not the only one; others can be used:

"For example, information retrieval systems often make use of proxies to 
interact with a multitude of URI schemes, such as HTTP proxies being used to 
access "ftp" and "wais" resources. [...] Likewise, future protocols may be 
defined that encompass our current systems, using entirely different interaction 
mechanisms, without changing the existing identifier schemes."
-- http://www.w3.org/TR/webarch/#dereference-uri

With RDF, URIs are often used to refer to things that cannot be retrieved on the 
Web; yet I think it may be important to be able to assign provenance to such 
resources. Yet the XG report seems to say that resources are those things for 
which representations can be retrieved using HTTP.


2. I think that treating provenance as something that can be accessed via 
content negotiation on a resource URI, of that's what is being proposed, is 
plain wrong.

"By design, a URI identifies one resource. Using the same URI to directly 
identify different resources produces a URI collision."
-- http://www.w3.org/TR/webarch/#URI-collision:

In this case, I would argue that provenance is a different resource from the 
entity to which it applies.

There was a vaguely similar issue raised by the IETF WebDAV working group, who 
introduced new HTTP methods for retrieving properties of resources.  This became 
standardized despite some discussion about the "URI collision" problem in the 
web architecture - two different resources accessible only via a common URI. 
Digging for more background, I found this:
-- http://lists.w3.org/Archives/Public/w3c-dist-auth/1998OctDec/0074.html

I'm a bit hazy about how this played out, but there was some discussion of this, 
e.g.
-- http://lists.w3.org/Archives/Public/ietf-http-wg/2007JulSep/0184.html

But rather than focus on the problems, I think there's something we can use to 
avoid these problems:
-- http://www.w3.org/TR/powder-dr/#assoc-linking
suggests several possible mechanisms;  I'm particularly thinking of the HTTP 
Link: header option, though the others might have a place too.

(This ref. thanks to a serendipitous online chat with Julian Reshcke)











Olaf Hartig wrote:
> Hello,
> 
> In our last telecon we agreed on a list of objectives for the F2F meeting [1]. 
> According to that list the Provenance Access and Query Task Force (PAQ TF) 
> will discuss a draft on how provenance fits in the Web architecture.
> The PAQ TF should start working on this draft as soon as possible (in parallel 
> to the work done in the Model TF). To kickstart this activity I would like to 
> bring up the following two proposals:
> 
> Proposal 1: The final report [2] of the W3C provenance incubator group contains 
> a section on "Provenance in Web Architecture", Sec.6. The PAQ TF uses this 
> section as foundation for the draft that we want to have for the F2F meeting. 
> By "foundation" I mean as a first incomplete (and inofficial) draft.
> 
> If we agree on Proposal 1, then we may decide about:
> 
> Proposal 2: To initiate the development of Sec.6 [2] into the draft that we 
> want to have for the F2F meeting, the PAQ TF performs the following four 
> actions:
> 
> 2.a) identify key terms in the overview section (Sec.6.1 [6]) and provide 
> references to definitions of these terms (preferably referring to W3C 
> documents)
> 
> 2.b) exemplify the different options mentioned in Sec.6 [2] using the data 
> journalism example [3]
> 
> 2.c) brainstorm and discuss additional pros and cons for the different options 
> mentioned in Sec.6 [2]
> 
> 2.d) brainstorm and discuss additional options that are not mentioned in
> Sec.6 [2] (if there are any)
> 
> 
> Greetings,
> Olaf
> 
> 
> [1] http://lists.w3.org/Archives/Public/public-prov-wg/2011May/0017.html
> [2] http://www.w3.org/2005/Incubator/prov/XGR-prov/
> [3] http://www.w3.org/2011/prov/wiki/ProvenanceExample
>

Received on Wednesday, 18 May 2011 10:59:44 UTC