Re: Interaction model vs data model

> 
>>>>> <> a ShoppingCartContainer;
>>>>> ldp:membershipPredicate :order .
>>>>> 
>>>>> and the client  now knows that if he posts something like
>>>>> 
>>>>> <> a Order;
>>>>> content [ a BarbieDoll ];
>>>>> for <http://joe.example/#me >;
>>>>> address <http://joe.example/#address> .
>>>> 
>>>> I think this kind of example can join the BugTracker for input about doing "services" with LDP. 
>>>> 
>>>> I do think that one of the good things about REST is that it eliminates pre-knowledge for the client. For example, there is magic in your example, i.e., the client has to know it is a Toyshop. It could be a selling Pizza .... and then what ?
>> 
>>> Now your question is good one: how do you delimit the type of things ordered.
>>> There are many possible answers. One would be to restrict the order relation
>>> using an owl restriction on the elements of an rdf collection named by 
>>> reference. Clearly more work is to be done there...
>> 
>> In my proposal for this kind of thing at http://lists.w3.org/Archives/Public/public-ldp-wg/2012Dec/0118.html I'm taking large amounts of inspiration from HTML. Therefore, to accomplish the above, we just need a select/option element for a robot ... i.e., we might have a "suggested" property which points to a LDP container - this means pick your type of Doll from the contents of this container. For similar (copying-html) reasons, I prefer POSTing sets of properties, rather than POSTing a graph. 
> 
> "I prefer POSTing sets of properties", which means that you are losing context. What is a property of? Some subject
> presumably. The aim is to make everything as explicit as possible for reasons I gave earlier
> 

Look to the Web. You are sent a form, you fill it out, and then return. You are responding to a request for a list of required parameters. And there is no context lost !! 

Roger