reidpr.wikisym.201110

1. Wiki Grows Up: Arbitrary Data Models, Access Control, and Beyond a talk by Reid Priedhorsky IBM T.J. Watson Research Center Collaborative User Experience Group WikiSym 2011

2. Wiki Grows Up: Arbitrary Data Models, Access Control, and Beyond a talk by Reid Priedhorsky IBM T.J. Watson Research Center Collaborative User Experience Group WikiSym 2011

3. a wiki map for bicyclists 2

4. why I’m here 3

5. why I’m here 3 objects 3

6. why I’m here 3 objects private object 3

7. why I’m here 3 objects private object ‣ratings ‣shared layers 3

8. why I’m here 3 objects doing both is hard private object ‣ratings ‣shared layers 3

9. it’s hard because of undo Felipe can edit objects A and B Andrea can edit object A but not B 4

10. it’s hard because of undo Felipe can edit objects A and B Andrea can edit object A but not B 1. Felipe saves a revision N of A and B 4

11. it’s hard because of undo Felipe can edit objects A and B Andrea can edit object A but not B 1. Felipe saves a revision N of A and B 2. Andrea wishes to revert N. 4

12. it’s hard because of undo Felipe can edit objects A and B Andrea can edit object A but not B 1. Felipe saves a revision N of A and B 2. Andrea wishes to revert N. 3. #fail :-( 4

13. talk outline Wiki 1.0 – per-object state Wikipedia, et al. + fine-grained access control Wiki 2.0 + global state Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control 5

14. talk outline independent objects Wiki 1.0 – per-object state Wikipedia, et al. + fine-grained access control Wiki 2.0 + global state Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control 5

15. talk outline Wiki 1.0 – per-object state Wikipedia, et al. + fine-grained access control arbitrary data Wiki 2.0 + global state Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control 5

16. talk outline Wiki 1.0 – per-object state Wikipedia, et al. + fine-grained access control arbitrary data like real version Wiki 2.0 + global state control software Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control 5

17. talk outline Wiki 1.0 – per-object state Wikipedia, et al. + fine-grained access control Wiki 2.0 + global state Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control arbitrary data + good access control 5

18. talk outline Wiki 1.0 – per-object state Wikipedia, et al. + fine-grained access control Wiki 2.0 + global state Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control 6

19. editing history of two articles Article Name Ver. Text Cat 1 Cats are mammals. Cat 2 Cats are cute mammals. Mouse 1 Mice have pointy noses. Cat 3 Cats are cute mammals with whiskers. Mouse 2 Mice have pointy noses that wiggle. 7

25. editing history of two articles Article Name Ver. Text Cat 1 Cats are mammals. Cat 2 Cats are cute mammals. Mouse 1 Mice have pointy noses. Cat 3 Cats are cute mammals with whiskers. Mouse 2 Mice have pointy noses that wiggle. unit of revision = one object 7

26. editing history of two articles ‣ Each object has independent state & history ‣ No well-deﬁned global state ‣ Multiple edits can’t be saved atomically Article Name Ver. Text Cat 1 Cats are mammals. Cat 2 Cats are cute mammals. Mouse 1 Mice have pointy noses. Cat 3 Cats are cute mammals with whiskers. Mouse 2 Mice have pointy noses that wiggle. unit of revision = one object 7

27. critical operation: undo An undo that is undone forms a no-op. 8

28. three ways to undo work in wikis 9

29. three ways to undo work in wikis 1. Manual editing 9

30. three ways to undo work in wikis 1. Manual editing 2. Revert offending revision N ... copy revision N – 1 and save it as a new revision ... destroys all work after N too 9

31. three ways to undo work in wikis 1. Manual editing 2. Revert offending revision N ... copy revision N – 1 and save it as a new revision ... destroys all work after N too 3. Reverse-merge offending revision N 9

32. Reverse-merging revision 2 of article “Cat” (Wikipedia calls this “undo”.) Article Name Ver. Text Cat 1 Cats are mammals. Cat 2 Cats are cute mammals. Mouse 1 Mice have pointy noses. Cat 3 Cats are cute mammals with whiskers. Mouse 2 Mice have pointy noses that wiggle. Cat 4 Cats are mammals with whiskers. 10

37. Reverse-merging revision 2 of article “Cat” (Wikipedia calls this “undo”.) remove cute from between Article and mammals are Name Ver. Text Cat 1 Cats are mammals. Cat 2 Cats are cute mammals. Mouse 1 Mice have pointy noses. Cat 3 Cats are cute mammals with whiskers. Mouse 2 Mice have pointy noses that wiggle. Cat 4 Cats are mammals with whiskers. 10

40. Reverse-merging revision 2 of article “Cat” (Wikipedia calls this “undo”.) remove cute from between Article and mammals are Name Ver. Text Cat 1 Cats are mammals. Cat 2 Cats are cute mammals. Mouse 1 Mice have pointy noses. Cat 3 Cats are cute mammals with whiskers. Mouse 2 Mice have pointy noses that wiggle. Cat 4 Cats are mammals with whiskers. reverse-merge + reverse-merge = no-op 10

41. access control in traditional wikis 11

42. access control in Wiki 1.0 Basic model: access control lists (ACLs) ... e.g., each “thing” has lists of who can do what Even Wikipedia uses ACLs ... e.g., ACL for editing most articles is “everyone” ... e.g., for protected articles it’s “all administrators” Natural granularity is one article Thus: unit of access control is one object ... i.e., unit of access control ≥ unit of revision 12

43. the point Traditional wikis have mature undo and ﬁne-grained access control, but lack global state management. 13

44. talk outline Wiki 1.0 – per-object state ✓ Wikipedia, et al. + fine-grained access control Wiki 2.0 + global state Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control 14

45. data model overview Edge Note Point Region 15

46. data model overview Edge Note Revision Point Region 15

47. data model overview Edge all versioning is controlled by this table Note Revision Point Region 15

48. data model overview Edge all versioning is controlled by this table Note Revision Point Region unit of revision = entire database at every instant, there is a well-deﬁned global state 15

49. Editing history of three articles Article ID Ver. VSR VBR Del? Name Text 16

50. Editing history of three articles Article ID Ver. VSR VBR Del? Name Text identiﬁer (integer) 16

51. Editing history of three articles Article ID Ver. VSR VBR Del? Name Text version (integer) 16

52. Editing history of three articles “valid before revision” Article ID Ver. VSR VBR Del? Name Text “valid starting revision” 16

53. Editing history of three articles Article ID Ver. VSR VBR Del? Name Text deleted ﬂag (boolean) 16

54. Editing history of three articles Revision 21: Create “Mouse” Article ID Ver. VSR VBR Del? Name Text 55 1 21 ∞ no Mouse Mice have pointy noses. 17

61. Editing history of three articles Revision 22: Create “Cat” and “Dog” Article ID Ver. VSR VBR Del? Name Text 55 1 21 ∞ no Mouse Mice have pointy noses. 66 1 22 ∞ no Cat Cats are mammals. 77 1 22 ∞ no Dog Dogs smell funny. 18

67. Editing history of three articles Revision 23: Alter text of “Cat” and “Mouse” Article ID Ver. VSR VBR Del? Name Text 55 1 21 ∞ no Mouse Mice have pointy noses. 66 1 22 ∞ no Cat Cats are mammals. 77 1 22 ∞ no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 ∞ no Cat Cats are cute mammals. 19

72. Editing history of three articles Revision 23: Alter text of “Cat” and “Mouse” Article ID Ver. VSR VBR Del? Name Text 55 1 21 ∞ 23 no Mouse Mice have pointy noses. 66 1 22 23 ∞ no Cat Cats are mammals. 77 1 22 ∞ no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 ∞ no Cat Cats are cute mammals. 19

73. Editing history of three articles r21 / 8:01 pm ‣ ‣ r22 / 8:30 pm Revision 23: Alter text of “Cat” and “Mouse”pm ‣ r23 / 8:47 Article ID Ver. VSR VBR Del? Name Text 55 1 21 ∞ 23 no Mouse Mice have pointy noses. 66 1 22 23 ∞ no Cat Cats are mammals. 77 1 22 ∞ no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 ∞ no Cat Cats are cute mammals. 19

74. Editing history of three articles r21 / 8:01 pm ‣ ‣ r22 / 8:30 pm Revision 23: Alter text of “Cat” and “Mouse”pm ‣ r23 / 8:47 Article ID Ver. VSR VBR Del? Name Text 55 1 21 ∞ 23 no Mouse Mice have pointy noses. 66 1 22 23 ∞ no Cat Cats are mammals. 77 1 22 ∞ no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 ∞ no Cat Cats are cute mammals. 19

75. Editing history of three articles r21 / 8:01 pm ‣ ‣ r22 / 8:30 pm Revision 23: Alter text of “Cat” and “Mouse”pm valid from 8:01:00.000 ‣ r23 / 8:47 to 8:46:59.999 Article ID Ver. VSR VBR Del? Name Text 55 1 21 ∞ 23 no Mouse Mice have pointy noses. 66 1 22 23 ∞ no Cat Cats are mammals. 77 1 22 ∞ no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 ∞ no Cat Cats are cute mammals. 19

76. Editing history of three articles Revision 24: Alter text of “Cat”, delete “Dog” Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 ∞ no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 ∞ no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 20

77. Editing history of three articles Revision 24: Alter text of “Cat”, delete “Dog” Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 ∞ no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 ∞ no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 20

81. undoing work under global state 21

82. Reverse-merge revision 23, creating revision 25 Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 55 3 25 ∞ no Mouse Mice have pointy noses. 66 4 25 ∞ no Cat Cats are mammals with whiskers. 22

86. Reverse-merge revision 23, creating revision 25 Article remove that wiggle ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 55 3 25 ∞ no Mouse Mice have pointy noses. 66 4 25 ∞ no Cat Cats are mammals with whiskers. 22

91. Reverse-merge revision 23, creating revision 25 remove cute Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 55 3 25 ∞ no Mouse Mice have pointy noses. 66 4 25 ∞ no Cat Cats are mammals with whiskers. 22

95. Reverse-merge revision 23, creating revision 25 Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ 25 no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ 25 no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 55 3 25 ∞ no Mouse Mice have pointy noses. 66 4 25 ∞ no Cat Cats are mammals with whiskers. 22

96. Reverse-merge revision 23, creating revision 25 Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ 25 no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ 25 no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 55 3 25 ∞ no Mouse Mice have pointy noses. 66 4 25 ∞ no Cat Cats are mammals with whiskers. 22 (see paper & backup slides for revert)

97. undoing under global state management Keep “undo that is undone = no-op” Generally: More complicated because the data is more complex ... see paper for details ... (Cyclopath does not do reverse-merge) But, no big deal 23

98. the point Now we have global state management. but: unit of access control = unit of revision (i.e., the whole database); too coarse. 24

99. talk outline Wiki 1.0 – per-object state ✓ Wikipedia, et al. + fine-grained access control Wiki 2.0 + global state ✓ Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control 25

100. talk outline Wiki 1.0 – per-object state ✓ Wikipedia, et al. + fine-grained access control Wiki 2.0 + global state ✓ Cyclopath now – no fine-grained access control Wiki 3.0 + global state Cyclopath future + fine-grained access control ‣ unit of access control < unit of revision ‣ meta access control 25

101. problem: undo Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 26

102. problem: undo Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 26

103. problem: undo Felipe can edit “Cat” and “Mouse” → no problem Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 26

104. problem: undo Felipe can edit “Cat” and “Mouse” → no problem Andrea can edit “Cat” but not “Mouse” → problem Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 26

105. problem: undo Felipe can edit “Cat” and “Mouse” → no problem Andrea can edit “Cat” but not “Mouse” → problem Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — Solution: partial undo 26

106. problem: undo Felipe can edit “Cat” and “Mouse” → no problem Andrea can edit “Cat” but not “Mouse” → problem Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — Solution: partial undo 26 Andrea reverts just “Cat”

107. partial undo to enable unit of access control < unit of revision Old: Undo entire revision or nothing at all New: Undo only part of a revision ... i.e., undo changes to objects I have access to Keep: “undo that is undone = no-op” ... iff second undo is a complete undo Need UI support to reduce confusion ... e.g., warn if introducing potential for partial undo ... e.g., special “completify undo” operation 27

108. meta access control i.e., constraints on access control lists 28

109. use cases from Cyclopath Public base map ... edges of transportation network must be public Private watch regions ... regions can be public or private Rate anything that can be seen, privately ... force ratings to be private ... allow rating anything, even if can’t edit other attributes Shared private layers ... force objects to have same permissions as the layer 29

110. implementation overview Databases + recursion = ☹ ... i.e., best to make access decision with just one lookup Each Cyclopath object has 4 ACLs ... viewing, searching, editing, changing access ... implemented w/ standard optimizations That’s basic access control Meta access control gives rules deﬁning valid ACL content 30 basic/meta model from Dewan & Shen, 1998

111. the point With partial undo and both basic & meta access control, wikis can implement both global state management and ﬁne-grained access control. 31

112. talk outline Wiki 1.0 – per-object state ✓ Wikipedia, et al. + fine-grained access control Wiki 2.0 + global state ✓ Cyclopath now – no fine-grained access control Wiki 3.0 + global state ✓ Cyclopath future + fine-grained access control 32

113. I’ve described ways to make wikis less simple and less open. Have we lost the spirit of the wiki model? 33

114. The 3 fundamental properties of the wiki model 34

115. The 3 fundamental properties of the wiki model 1. Inverted publishing model ... review after publication, not before 34

116. The 3 fundamental properties of the wiki model 1. Inverted publishing model ... review after publication, not before 2. Maximally open access ... whenever reasonable, anyone can change anything ... minimize e.g. unfriendly UI, unfriendly culture 34

117. The 3 fundamental properties of the wiki model 1. Inverted publishing model ... review after publication, not before 2. Maximally open access ... whenever reasonable, anyone can change anything ... minimize e.g. unfriendly UI, unfriendly culture 3. Transparent changes ... everyone can see who is changing what ... recent changes lists, watching, difﬁng ... enables meta-work (notably, undoing bad edits) 34

118. the point Our radical new collaboration model, the wiki, has great promise in many domains. Why limit ourselves to relatively unstructured data or contexts with simple access control needs? 35

119. the end Reid Priedhorsky and Loren Terveen reid@reidster.net http://reidster.net/research/

120. Cyclopath revisions 37

121. Cyclopath revisions in example: 26 edges, 9 notes 37

122. Cyclopath revisions in example: 26 edges, 9 notes of 13k revisions: 60% alter graph 65% alter >1 object 37

123. Reverting revision 2 of article “Cat” Article Name Ver. Text Cat 1 Cats are mammals. Cat 2 Cats are cute mammals. Mouse 1 Mice have pointy noses. Cat 3 Cats are cute mammals with whiskers. Mouse 2 Mice have pointy noses that wiggle. Cat 4 Cats are mammals. 38

130. Reverting revision 23, creating revision 25 Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 55 3 25 ∞ no Mouse Mice have pointy noses. 66 4 25 ∞ no Cat Cats are mammals. 39

136. Reverting revision 23, creating revision 25 Article ID Ver. VSR VBR Del? Name Text 55 1 21 23 no Mouse Mice have pointy noses. 66 1 22 23 no Cat Cats are mammals. 77 1 22 24 no Dog Dogs smell funny. 55 2 23 ∞ 25 no Mouse Mice have pointy noses that wiggle. 66 2 23 24 no Cat Cats are cute mammals. 66 3 24 ∞ 25 no Cat Cats are cute mammals with whiskers. 77 2 24 ∞ yes — — 55 3 25 ∞ no Mouse Mice have pointy noses. 66 4 25 ∞ no Cat Cats are mammals. 39

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