Re: membershipSubject clarification

On 30 Apr 2013, at 18:11, Arnaud Le Hors <lehors@us.ibm.com> wrote:

> Hi all, 
> On Monday we agreed to close Issue-61 which suggested to drop membershipSubject and focus on clarifying the spec instead. 
> To get us started I'd like to highlight that the editor's draft has an expanded example 3 which may clarify things a bit: 
> 
> # The following is an elaborated representation of
> #   http://example.org/netWorth/nw1
> @prefix ldp: <http://www.w3.org/ns/ldp#>.
> @prefix o: <http://example.org/ontology/>.
> <>
>   a o:NetWorth;
>   o:netWorthOf <http://example.org/users/JohnZSmith>;
>   o:asset 
>      <assetContainer/a1>,
>      <assetContainer/a2>;
>   o:liability 
>      <liabilityContainer/l1>,
>      <liabilityContainer/l2>,
>      <liabilityContainer/l3>.
> 
> <assetContainer/>
>   a ldp:Container;
>   dcterms:title "The assets of JohnZSmith";
>   ldp:membershipSubject <.>;
>   ldp:membershipPredicate o:asset.
> 
> <liabilityContainer/>
>   a ldp:Container;
>   dcterms:title "The liabilities of JohnZSmith";
>   ldp:membershipSubject <.>;
>   ldp:membershipPredicate o:liability. 
> 
> This defines two containers (assetContainer and libabilityContainer) corresponding two different membership predicates (respectively o:asset and o:liability) around the same subject resource (netWorth/nw1). 

1. does the ldp:membershipSubject have to be a document such as <> ? ( which in the example above is a o:NetWorth )
    a. if yes: how would one add a relation to a thing such as a person <#me> a foaf:Person ?
    b. if no: why is the relation called membership subject? Does this imply that the o:asset relation is an rdf:subProperty of rdf:member.
      I don't think that if I want to create a document I want to necessarily think of the document I created in say <assetContainer> as being a ldp:member of me.
 
  Consider the following example
 
   {
      <#me> a foaf:Person;
      foaf:depicts <portrait/img1> ;
      cal:attending <meetings/meet1> .
      
       <portrait/> a ldp:Container;
         dcterms:title "The assets of JohnZSmith";
         ldp:membershipSubject <#me>;
         ldp:membershipPredicate foaf:depicts.

       <meetings/>
         a ldp:Container;
         dcterms:title "The liabilities of JohnZSmith";
         ldp:membershipSubject <.>;
         ldp:membershipPredicate cal:attending. 
    } 
 
    Is this ok?

2. Would it not be a good thing if a GET on <portrait/> returned the following

    <> a ldp:Container;
         dcterms:title "The assets of JohnZSmith";
         ldp:membershipSubject <#me>;
         ldp:membershipPredicate foaf:depicts;
         rdfs:member <img1>, <img2> .

    and of course if <meetings> mentioned its rds:member ?

3. What if I want the object of the relation from the ldp:membershipSubject to the the object to be something described by the created  
resource? Say I want to create a resource that contains a <#me> and the ldp:membershipPredicate should be a foaf:knows relation to the object
( perhaps a <#him> in the created document? )
 
4. Can I have a number of different membershipSubjects?

Guess
-----

  My feeling is that what is wanted is some way to describe how contents of the POSTed
graph get tied to other resources managed by the server. My feeling is that this is
a good idea, but orthogonal to the rdf:member of an LDPC. 

Henry

> 
> I would appreciate if Henry and others could ask specific questions about this design so we can try to answer them and see how the spec needs to be clarified. 
> 
> Thanks.
> --
> Arnaud  Le Hors - Software Standards Architect - IBM Software Group

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