ISSUE-71: No membershipSubject or membershipPredicate

membershipX

No membershipSubject or membershipPredicate

State:
CLOSED
Product:
Linked Data Platform Spec
Raised by:
Henry Story
Opened on:
2013-05-21
Description:
There are a lot of arguments against membershipXXX relations:

- ISSUE-75 monotonicity: there is a deep semantic problem with the default values of the properties. Removing default values won't solve the problem, as then there is a modelling problem: these relations should be thought of as rules that help one to conclude to the ldp:contains relations - but in that case they need to be modelled via blank nodes
<> a ldp:Container;
ldp:membership [ predicate x:attachment; subject <..> ]
as explained in http://lists.w3.org/Archives/Public/public-ldp-wg/2013May/0335.html

- ISSUE-78 inferencing: but if these are disguised inferencing rules then we are probably going beyond the minimal desirable requirement on clients expressed in the spec.

- ISSUE-72 membershipObject: without an object version of the properties one is seriously limiting what can be expressed by the rule, and one shoehorns developers into failing to distinguish LDPRs from non information resources, ie fails to distinguish documents from what they are about. This means that one makes it difficult to express document authorship and copyright properties.

The above arguments show that one needs to remove the ldp:membershipXXX relations.

Replacing the lost functionality:
---------------------------

The question then is with what does one replace the lost functionality. ( This should perhaps be a new issue ). For that one needs to be very clear as to what the use cases for these relations are. The best use case I have seen so far is Steve Speicher's bug example:
http://lists.w3.org/Archives/Public/public-ldp-wg/2013May/0250.html
which shows that the aim has been to allow an ldpr to tell the user how by POSTing to an LDPC he can create a relation from the ?ldpr ( or a resource defined within it ) to the newly created resource ( or with ISSUE-72 to a newly created resource defined within it )

But this is compatible with it being possible for non-reasoning clients ( ISSUE-78 ) to read LDPCs and work out what the ldpc's members are ( ISSUE-73 (rdf:member) and ISSUE-79 (ldp:contains)), without needing to do that reasoning. Ie: it would be better to list the ldp:members in LDPCs clearly, and have the reasoning be there to tell clients what the effect of POSTing a new resource will be: create a new relation ( and if possible do this declaratively ). Currently it is the opposite that is happening: reasoning is required to tell what the members of an ldpc is.

One should perhaps also consider that one could do without the rules telling a client how to add a new relation by POSTing to a LDPC. That is one could allow the client to
1. Create a new LDPR by POSTing to an LDPC
2. Add a relation from some LDPRs to the LDPC using PATCH

Or one could define consistency spaces. Ie the client could POST information with the required links, and the server would add bidirectional relations POSTed by the client. Ie perhaps in the bug example the client can POST relations with links to the existing LDPR.

~~~~POST /ldpc/ HTTP/1.1 ~~~~~~~~~~
<otherbug#bug> beatle:relatesTo <> .
<> a beatle:BugReport;
dc:title "Another silly bug";
dc:author </joe#me> ;
...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

And the client would know that the server is going to add

<otherbug#bug> beatle:relatesTo <> .

to <otherbug>
There may be other ways to get the same functionality and better if one starts to think
about this problem afresh.
Related Actions Items:
No related actions
Related emails:
  1. updated ISSUE-71: membershipX description (from henry.story@bblfish.net on 2013-06-03)
  2. Re: ISSUE-75 Non-montonic - was: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-31)
  3. Re: ISSUE-75 Non-montonic - was: ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-31)
  4. Re: ISSUE-75 Non-montonic - was: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-31)
  5. Re: ISSUE-75 Non-montonic - was: ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-31)
  6. Re: ISSUE-75 Non-montonic - was: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-31)
  7. Re: ISSUE-75 Non-montonic - was: ISSUE-71: second bug tracking example (from kidehen@openlinksw.com on 2013-05-31)
  8. Re: ISSUE-75 (was ISSUE-71: second bug tracking example) (from johnarwe@us.ibm.com on 2013-05-31)
  9. Re: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-31)
  10. Re: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-31)
  11. ISSUE-75 Non-montonic - was: ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-31)
  12. Re: Issue-71: the first bug tracking example (from rgarcia@fi.upm.es on 2013-05-31)
  13. Re: ISSUE-75 (was ISSUE-71: second bug tracking example) (from bertails@w3.org on 2013-05-30)
  14. Re: ISSUE-75 (was ISSUE-71: second bug tracking example) (from lehors@us.ibm.com on 2013-05-30)
  15. Re: ISSUE-71: second bug tracking example (from bertails@w3.org on 2013-05-30)
  16. Re: ISSUE-71: second bug tracking example (from lehors@us.ibm.com on 2013-05-30)
  17. Re: ISSUE-71: second bug tracking example (from bertails@w3.org on 2013-05-30)
  18. Re: ISSUE-71: second bug tracking example (from lehors@us.ibm.com on 2013-05-30)
  19. Re: Issue-71: the first bug tracking example (from johnarwe@us.ibm.com on 2013-05-30)
  20. Re: ISSUE-71: second bug tracking example (from kidehen@openlinksw.com on 2013-05-30)
  21. Re: ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-30)
  22. Re: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-30)
  23. Re: ldp-ISSUE-75 (monotonicity): rdf:membershipProperty makes LDP PATCHing non-monotonic [Linked Data Platform core] (from henry.story@bblfish.net on 2013-05-30)
  24. Re: Missing use case for supporting ldp:membershipPredicate/Subject (from roger.menday@uk.fujitsu.com on 2013-05-30)
  25. Re: ldp-ISSUE-75 (monotonicity): rdf:membershipProperty makes LDP PATCHing non-monotonic [Linked Data Platform core] (from roger.menday@uk.fujitsu.com on 2013-05-30)
  26. Re: ldp-ISSUE-75 (monotonicity): rdf:membershipProperty makes LDP PATCHing non-monotonic [Linked Data Platform core] (from henry.story@bblfish.net on 2013-05-30)
  27. Re: Issue-71: the first bug tracking example (from rgarcia@fi.upm.es on 2013-05-30)
  28. Re: Missing use case for supporting ldp:membershipPredicate/Subject (from henry.story@bblfish.net on 2013-05-30)
  29. Re: ldp-ISSUE-75 (monotonicity): rdf:membershipProperty makes LDP PATCHing non-monotonic [Linked Data Platform core] (from lehors@us.ibm.com on 2013-05-29)
  30. Re: Missing use case for supporting ldp:membershipPredicate/Subject (from sspeiche@gmail.com on 2013-05-29)
  31. Re: Missing use case for supporting ldp:membershipPredicate/Subject (from henry.story@bblfish.net on 2013-05-29)
  32. ldp-ISSUE-75 (monotonicity): rdf:membershipProperty makes LDP PATCHing non-monotonic [Linked Data Platform core] (from sysbot+tracker@w3.org on 2013-05-29)
  33. Re: ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-29)
  34. Re: Issue-71: the first bug tracking example (from nmihindu@fi.upm.es on 2013-05-29)
  35. Re: Issue-71: the first bug tracking example (from lehors@us.ibm.com on 2013-05-29)
  36. Re: ISSUE-71: second bug tracking example (from lehors@us.ibm.com on 2013-05-29)
  37. Re: Missing use case for supporting ldp:membershipPredicate/Subject (from henry.story@bblfish.net on 2013-05-29)
  38. Re: Missing use case for supporting ldp:membershipPredicate/Subject (from bertails@w3.org on 2013-05-29)
  39. Re: ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-29)
  40. Re: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-29)
  41. Re: Issue-71: the first bug tracking example (from bertails@w3.org on 2013-05-29)
  42. Re: Issue-71: the first bug tracking example (from johnarwe@us.ibm.com on 2013-05-29)
  43. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-29)
  44. Re: ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-29)
  45. Re: Issue-71: the first bug tracking example (from lehors@us.ibm.com on 2013-05-28)
  46. Missing use case for supporting ldp:membershipPredicate/Subject (from sspeiche@gmail.com on 2013-05-28)
  47. Re: Issue-71: the first bug tracking example (from johnarwe@us.ibm.com on 2013-05-28)
  48. Re: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-28)
  49. Re: ISSUE-71: second bug tracking example (from johnarwe@us.ibm.com on 2013-05-28)
  50. Re: ldp-ISSUE-73 (rdf:member): LDPCs to list all their rdf:member [Linked Data Platform core] (from henry.story@bblfish.net on 2013-05-25)
  51. Re: ldp-ISSUE-73 (rdf:member): LDPCs to list all their rdf:member [Linked Data Platform core] (from nmihindu@fi.upm.es on 2013-05-24)
  52. Re: ldp-ISSUE-73 (rdf:member): LDPCs to list all their rdf:member [Linked Data Platform core] (from lehors@us.ibm.com on 2013-05-24)
  53. Re: ISSUE-71: second bug tracking example (from nmihindu@fi.upm.es on 2013-05-23)
  54. Re: ISSUE-71: second bug tracking example (from nmihindu@fi.upm.es on 2013-05-23)
  55. Re: ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-23)
  56. Re: Issue-71: the first bug tracking example (from rgarcia@fi.upm.es on 2013-05-23)
  57. Re: ISSUE-71: second bug tracking example (from nmihindu@fi.upm.es on 2013-05-23)
  58. Re: Issue-71: the first bug tracking example (from roger.menday@uk.fujitsu.com on 2013-05-22)
  59. Re: Issue-71: the first bug tracking example (from Erik.Wilde@emc.com on 2013-05-22)
  60. Re: Issue-71: the first bug tracking example (from bertails@w3.org on 2013-05-22)
  61. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-22)
  62. Re: Issue-71: the first bug tracking example (from roger.menday@uk.fujitsu.com on 2013-05-22)
  63. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-22)
  64. Re: Issue-71: the first bug tracking example (from lehors@us.ibm.com on 2013-05-22)
  65. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-22)
  66. Re: Issue-71: the first bug tracking example (from lehors@us.ibm.com on 2013-05-22)
  67. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-22)
  68. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-22)
  69. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-22)
  70. Re: Issue-71: the first bug tracking example (from nmihindu@fi.upm.es on 2013-05-22)
  71. Re: Issue-71: the first bug tracking example (from Roger.Menday@uk.fujitsu.com on 2013-05-22)
  72. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-22)
  73. ISSUE-71: second bug tracking example (from henry.story@bblfish.net on 2013-05-22)
  74. Re: Issue-71: the first bug tracking example (from lehors@us.ibm.com on 2013-05-21)
  75. Re: Issue-71: the first bug tracking example (from Roger.Menday@uk.fujitsu.com on 2013-05-21)
  76. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-21)
  77. Re: Issue-71: the first bug tracking example (from roger.menday@uk.fujitsu.com on 2013-05-21)
  78. Re: Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-21)
  79. Issue-71: the first bug tracking example (from henry.story@bblfish.net on 2013-05-21)
  80. ldp-ISSUE-71 (membershipX): No membershipSubject or membershipPredicate [Linked Data Platform core] (from sysbot+tracker@w3.org on 2013-05-21)

Related notes:

Resolution: Close Issue-71, no changes, all related issues have been closed.
See http://www.w3.org/2013/meeting/ldp/2013-06-20#resolution_10

Arnaud Le Hors, 20 Jun 2013, 16:15:46

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