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Moving forward on Site Metadata

From: Mark Nottingham <mnot@yahoo-inc.com>
Date: Mon, 24 Apr 2006 11:09:03 -0700
Message-Id: <8AEF770D-8767-4937-8AB2-1335F19C90A6@yahoo-inc.com>
To: www-tag@w3.org

What's the status of the Site Metadata work? From the Web site, it  
doesn't appear if any progress has been made in some time.

I ask because it's getting quite relevant; e.g., there is a Task  
Force that's looking at mechanisms for cross-site access control  
<http://lists.w3.org/Archives/Member/member-accesscontrol-tf/>, and a  
site metadata format is one potential solution. Additionally,  
individual groups, sites and services continue to develop ad hoc site  
metadata formats. Combined with the growing popularity of  
microformats, service description, etc., I suspect Web metadata is  
about to become a lot more useful and prevalent, and site metadata is  
part of that.

I also wonder if it would help the TAG to bite off a more manageable  
piece of the site metadata problem, by first considering what the  
appropriate uses of site metadata are.

In particular, some people argue that any sort of site-wide metadata  
is bad, because it disadvantages people who don't have control over a  
whole site;

On the other hand, there are use cases that require knowledge of  
metadata for a particular resource before accessing it; for example,  
privacy policy, robots policy, and other access control policy (which  
is very relevant, as there's currently a TF looking at that topic).

In these cases, doing a resource-specific policy request before each  
request incurs too much of an overhead to be practical. For many of  
them, a site-wide metadata format is very attractive (as seen in P3P  
and Robot Exclusion).

Perhaps it would help to develop guidelines for the establishment of  
new types of site-wide metadata, e.g.:
   - Site metadata is most appropriate when it is applicable to a  
potentially large number of resources, knowledge of it is necessary  
before access to a resource.
   - Site metadata is least approrpriate when it is specific to a  
small number of resources, and knowledge of it is necessary before  
access to a resource.
   - Site metadata should be able to be mirrored in content (e.g.,  
meta tags, microformat) and in HTTP headers (e.g., the Link header).
   - Site metadata formats should be modular; it should be possible  
to delegate authority to part of a site to a different resource  
(e.g., policy for /foo/ delegated to /foo/policy.xml).


Mark Nottingham
Received on Monday, 24 April 2006 18:12:01 UTC

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