W3C home > Mailing lists > Public > public-ldp-wg@w3.org > November 2012

Re: Creation of Containers

From: Alexandre Bertails <bertails@w3.org>
Date: Thu, 08 Nov 2012 08:29:23 -0500
Message-ID: <509BB3B3.9020808@w3.org>
To: Roger Menday <roger.menday@uk.fujitsu.com>
CC: Henry Story <henry.story@bblfish.net>, "Wilde, Erik" <Erik.Wilde@emc.com>, "public-ldp-wg@w3.org" <public-ldp-wg@w3.org>, nathan <nathan@webr3.org>
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.


> 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/
Received on Thursday, 8 November 2012 13:29:49 UTC

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