relProperty Re: [uf-rest] Roy Fielding on WebDAV and PROPs

[Ernest Prabhakar]

You're certainly welcome to talk about it on this list, as long as it  
doesn't get too far afield.  Profiles themselves are very near-and- 
dear to microformats, and definitely on topic.

I myself know virtually nothing about HTTP internals, so I'm not  
likely to contribute much. :-)

-- Ernie P.

On Apr 12, 2006, at 3:00 PM, Mark Nottingham wrote:

> For other reasons, I've been thinking of putting together an I-D to  
> revive the Link HTTP header, along with a separate header to  
> capture the URI(s) of the profile(s) in effect for the content.
>
> Interested?
>
> On 2006/04/12, at 2:55 PM, Dr. Ernie Prabhakar wrote:
>
>> Hi Larry,
>>
>> On Apr 12, 2006, at 2:11 PM, Larry Masinter wrote:
>>> After Yaron's bed time story and a 9 year slumber...
>>>
>>> What was I thinking? Clearly, URL munging isn't so bad, if you
>>> add:
>>>
>>>> where ",properties" is a site-configurable string. It needs to be
>>>> advertised by some sort of site metadata; e.g., in OPTIONS
>>
>> Right, the key is that it has to be *advertised*, not implicitly  
>> *assumed*.
>>
>>> Putting on a different hat, I'll point out another option ...
>>> put the metadata *in* the data:
>>>
>>>     http://www.adobe.com/products/xmp
>>>
>>> For the descriptive metadata for which this is appropriate,
>>> you don't need a separate URI, the latency of a separate
>>> GET request, etc.
>>
>> Yeah, I think someone has already come up with a convention for  
>> embedding metadata in web documents:
>>
>> http://www.w3.org/TR/REC-html40/struct/global.html#h-7.4.4
>>
>> :-)
>>
>> As it happens, these in fact use the same profile as microformats:
>>
>> http://www.w3.org/TR/REC-html40/struct/global.html#adef-profile
>>
>> The issue at stake, though, is how to advertise metadata that is  
>> *not* a proper part of the actual document, which is why I think  
>> we need <link> or Link:
>>
>> I've started a Wiki page to capture the discussion so far.  Please  
>> feel free to add questions or comments; let me know if you need  
>> write access.
>>
>> http://microformats.org/wiki/rest/property
>>
>> -- Ernie P.
>>
>> = The Problem =
>>
>> HTML has long used the [http://www.w3.org/TR/REC-html40/struct/ 
>> global.html#h-7.4.4 meta] tag for metadata to describe the  
>> ''contents'' of a document.  While this works well for "intrinsic"  
>> metadata related to authoring, there's no equivalent function for  
>> "extrinsic" metadata provided by the server or external sources.
>>
>> To address this need, [WebDAV] defined a new set of "PROP" methods  
>> to create, search, and retrieve '''properties'''.  Unfortunately,  
>> in addition to defining a whole new protocol this violates the  
>> [rest]ful notion of each resource having a URL for manipulating  
>> it.  This raises the question, "What is the RESTful way to use  
>> HTML and HTTP to provide useful properties."
>>
>> = Proposal =
>> == relProperty ==
>>
>> Our proposal, currentlly called "relProperty", is motivated by the  
>> following principles:
>>
>> # Every property must have at least one well-defined URL which can  
>> be retrieved and updated.
>> # There must be an easy way to discover all the properties  
>> associated with a given document.
>> # It must be simple to implement on existing web servers without  
>> requiring non-trivial modifications
>> # It should respect and build on existing [http://microformats.org/ 
>> about/ microformat principles] and practices
>> # It should be consistent with URL [[rest/opacity]] (properly  
>> understood)
>>
>> == &lt;link> ==
>>
>> Together, this implies that that the optimal way to associate a  
>> property with a document is via the HTML [ link] tag (or the  
>> equivalent HTTP "Link:").  This provides the requisite mechanism  
>> for telling the client how to construct an appropriate URL for  
>> getting or setting each property, as in:
>>
>>  &lt;link rel="property" href=".;prop1">
>>
>> == ;property ==
>>
>> It is conventional, but not mandatory, to use a semicolon (";") as  
>> the first character of each property.  This follows the convention  
>> used in, e.g. [http://www.macromedia.com/cfusion/knowledgebase/ 
>> index.cfm?id=1c6b723 ColdFusion], and eases human-readability.
>>
>> = Examples =
>> * TBD
>>
>> = Open Issues =
>>
>> * Can properties be chained together? If so, are they retrieved in  
>> parallel, or would those be subproperties?
>> * Would we need to worry about [http://lists.evolt.org/archive/ 
>> Week-of-Mon-20020114/065707.html semicolon exploits]?
>> * Are there other conventions we should follow/avoid?
>> * Should the "Link:" tag itself be declared in HTTP "OPTIONS"?
>>
>> _______________________________________________
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>> microformats-rest at microformats.org
>> http://microformats.org/mailman/listinfo/microformats-rest
>>
>
>
> --
> Mark Nottingham     http://www.mnot.net/
>