Re: issue-34 example

hi Andy, 

>> It seems that we will never see eye-to-eye on this :)
>> I just think that what you want to do with LDP, is different from what I want to do.
>> 
>> I want solutions where servers which guide my clients through a service. If it is "unfriendly week", the hypermedia directing linking with the :friend predicate shouldn't be there. Your solution is essentially allowing any data to be added.
>> 
>> Would you agree ?
> 
> I agree that I want LDP to support adding arbitrary data.  May not be 
> the only usage and some implementations may not allow the opertation 
> (thay can always refuse anything).

Well, the server can always refuse something which would otherwise put the system into an 'illegal' state - but, this isn't the most helpful way of going about things. 

btw: In the 'graph and links model', a resource might either be liberal about which other properties it accepts (or not). This then is a model which covers both arbitrary and constrained data interaction.  

>> 
>> I hope we can support both in LDP (I think we can).
> 
> I hope so - I'm having difficulty seeing what state manipulations you 
> have in mind.  Do you have a concrete example?

Yes ! our LDP example - the Bug tracker.

It seems that most (almost all) applications have some constraints on how a graph may be evolved by LDP. A concrete, simple example started this email thread; friends and enemies - if I want to add a new arc to a Person, called :friend, it is only allowed to link to another person, etc etc ... 

I believe you will see similar constraints in pretty much any "Web API" or "REST API" around on the web. 

Roger

> Isn't the only state is the RDF of a LDP-R?  A unique characteristic 
> here is that an LDP has no hidden/implicit state?



> 
> 	Andy
> 
>> 
>> Roger
>> 
>> 
>>> POST, as it's simply additional triples:
>>> 
>>> <Person/1> :friend <Person/4> .
>>> 
>>> This follows from "Extending a database through an append operation."
>>> (RFC 2616)
>>> 
>>> (it would be valuable to be explicit that POST to LDP-R is add triples)
>>> 
>>> 	Andy
>>> 
>>> On 18/01/13 00:25, Arnaud Le Hors wrote:
>>>> Hi Roger,
>>>> 
>>>> I have to admit not to understand how your example justifies adding
>>>> anything to LDP.
>>>> 
>>>> The spec as it stands allows you to update resources via PUT. Why isn't
>>>> it enough to PUT the new representation with the added Person? Why does
>>>> your resource have to be anything special to the server rather than just
>>>> another RDF resource which happens to contain references to a bunch of
>>>> resources in a totally standard RDF fashion?
>>>> --
>>>> Arnaud  Le Hors - Software Standards Architect - IBM Software Group
>>>> 
>>>> 
>>>> Roger Menday <roger.menday@uk.fujitsu.com> wrote on 01/17/2013 02:31:18 PM:
>>>> 
>>>>> From: Roger Menday <roger.menday@uk.fujitsu.com>
>>>>> To: "public-ldp-wg@w3.org Group" <public-ldp-wg@w3.org>,
>>>>> Date: 01/17/2013 02:32 PM
>>>>> Subject: issue-34 example
>>>>> 
>>>>> 
>>>>> Given the following LD.
>>>>> 
>>>>> <Person/1>
>>>>>   :friend <Person/7>, <Person/9>
>>>>>   :enemy <Person/6>
>>>>> 
>>>>> Issue-34 says it needs a simple way of linking a new friend
>>>>> (<Person/4>), to end up with
>>>>> 
>>>>> <Person/1>
>>>>>   :friend <Person/7>, <Person/9>, <Person/4>
>>>>>   :enemy <Person/6>
>>>>> 
>>>>> ?
>>>>> 
>>>>> So, I believe that aggregation is an essential piece for lDP.
>>>>> 
>>>>> regards,
>>>>> Roger
>>> 
>> 
>