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Re: Creation of Containers

From: Henry Story <henry.story@bblfish.net>
Date: Thu, 8 Nov 2012 14:41:59 +0100
Cc: Roger Menday <roger.menday@uk.fujitsu.com>, "Wilde, Erik" <Erik.Wilde@emc.com>, "public-ldp-wg@w3.org" <public-ldp-wg@w3.org>, nathan <nathan@webr3.org>
Message-Id: <87D839CF-E19C-419C-AAD8-8B02250D753D@bblfish.net>
To: Alexandre Bertails <bertails@w3.org>

On 8 Nov 2012, at 14:29, Alexandre Bertails <bertails@w3.org> wrote:

> On 11/08/2012 05:40 AM, Roger Menday wrote:
>> 
>> On 8 Nov 2012, at 08:25, Henry Story wrote:
>> 
>>> 
>>> On 8 Nov 2012, at 00:56, "Wilde, Erik" <Erik.Wilde@emc.com> wrote:
>>> 
>>>> hello henry.
>>>> 
>>>> On 2012-11-07 15:27 , "Henry Story" <henry.story@bblfish.net> wrote:
>>>>> On 8 Nov 2012, at 00:12, "Wilde, Erik" <Erik.Wilde@emc.com> wrote:
>>>>>> that's what on the web media types are doing. i know that this is way
>>>>>> outside of the scope of this group, but since we're saying REST in the
>>>>>> charter, this is what we would be doing in a RESTful design: design a
>>>>>> media type that represented the concepts we're building interactions
>>>>>> around, and then making the distinction you're pointing out is done by
>>>>>> virtue of the media type.
>>>>> I think you are trying to put too much in the media types. The Media type
>>>>> is just a way to interpret a document - i.e. to extract its semantics.
>>>> 
>>>> nope, it's more than that. it defines the set of interconnected resources
>>>> a client can traverse, and defines that traversing this set of resources
>>>> means. for every link that a client can find, the media type specifies why
>>>> a client might want to follow that link, and maybe what a client has to do
>>>> when following that link.
>>> 
>>> You can do that with RDF too, you just choose special vocabularies instead
>>> of choosing special mime types.
>> 
>> I agree with that. we don't want to go the way of many REST apis where a new mediatype is defined for each (XML schema) type in the system. I think that one mime type will be enough for LDP.
> 
> The cost of looking at the RDF to decide what to do may be pretty high.

Not if you can POST a SPARQL query on the Container. Eg: 

ASK { <> a ldp:Container }

On the other hand that still only gives you what the document says. What you may want
is to query the metadata about that container. 

> 
> Alexandre.
> 
>> 
>> Roger
>> 
>>> 
>>> 
>>>> 
>>>>> 
>>>>>> yup, and that would be the header signaling the media type.
>>>>> As said above that would be like saying that servers MUST speak a
>>>>> different
>>>>> language from the other documents they are serving, which seems arbitrary.
>>>> 
>>>> it's the opposite. it's the difference in functionality that's exposed as
>>>> media types.
>>> 
>>> That's a mistake, that just happens to work.
>>> 
>>>> if you are an XML database, you accept any XML and just store
>>>> it. that's fine. if you also allow people to interact with any kind of
>>>> management functionality of the database, what you exchange is still XML,
>>>> but its meaningful (let's say some XACML for managing access right) and
>>>> thus labeled by a media type that makes that distinction clear. that's
>>>> just how HTTP works.
>>> 
>>> Http allows you to do content negotiation on a resource to get back
>>> a preferred representation of that resource. All representations returned
>>> should be pretty much equal. That is where the idea of semantics comes from:
>>> there is something all these representations have in common.
>>> 
>>> What you are describing is in my view just a lucky error that people on
>>> REST mailing lists have used because it seems enough like it solves the
>>> problem, when in fact it just makes things more complicated. For example
>>> that way of working makes things a lot more complicated as all of a sudden
>>> you have to create a whole syntax for servers to work with, just to
>>> distinguish when the server is speaking  from when the document is served by
>>> it but is not a statement made by the  server.
>>> 
>>> That solution is at the wrong place at the logical layer. What you want is
>>> information about WHO said something, and the solution you are describing
>>> is telling me HOW it is said. Then there is a backchannel convention of which
>>> actors can say something which way to get to the WHO.
>>> 
>>> Much simpler would be to at least start out by thinking about WHO is
>>> saying something, since the original problem was at that layer. Is the
>>> server telling me that this is a collection? Or is this just a document
>>> someone else wrote saying it is a collection?
>>> 
>>> In any case on could also just argue: don't put a document saying
>>> 
>>>  <> a ldp:Container
>>> 
>>> anywhere. It would be like putting up a web page that was lying, and people
>>> will end up removing links to that resource, and distrusting servers that
>>> publish it. If one wanted to help servers publish documents of people on the
>>> web they did not fully control, then it would be useful to allow the server to
>>> say that it is not responsible for what is in the document.
>>> 
>>>> 
>>>> cheers,
>>>> 
>>>> dret.
>>>> 
>>> 
>>> Social Web Architect
>>> http://bblfish.net/
>>> 
>> 
> 

Social Web Architect
http://bblfish.net/



Received on Thursday, 8 November 2012 13:42:38 UTC

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