reidpr.wikisym.201110

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

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

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a wiki mapfor bicyclists 2

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why I’m here 3

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why I’m here 3 objects 3

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why I’m here 3 objects private object 3

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

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

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it’s hard becauseof undo Felipe can edit objects A and B Andrea can edit object A but not B 4

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it’s hard becauseof 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

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it’s hard becauseof 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

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it’s hard becauseof 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

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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

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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

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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

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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

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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

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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

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editing history oftwo 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

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editing history oftwo 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

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editing history oftwo 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

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

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three ways toundo work in wikis 9

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three ways toundo work in wikis 1. Manual editing 9

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three ways toundo 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

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three ways toundo 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

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Reverse-merging revision 2of 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

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Reverse-merging revision 2of 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

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Reverse-merging revision 2of 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

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access control intraditional wikis 11

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access control inWiki 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

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

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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

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data model overview Edge Note Point Region 15

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data model overview Edge Note Revision Point Region 15

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

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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

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Editing history ofthree articles Article ID Ver. VSR VBR Del? Name Text 16

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

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

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

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

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

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Editing history ofthree 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

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Editing history ofthree 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

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Editing history ofthree 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

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Editing history ofthree 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

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Editing history ofthree 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

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Editing history ofthree 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

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Editing history ofthree 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

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Editing history ofthree 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

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undoing work underglobal state 21

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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

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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

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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

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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

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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)

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undoing under globalstate 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

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

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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

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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

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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

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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

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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

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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

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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

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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”

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partial undo toenable 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

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

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use cases fromCyclopath 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

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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

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

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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

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

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The 3 fundamentalproperties of the wiki model 34

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

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The 3 fundamentalproperties 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

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The 3 fundamentalproperties 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

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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

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the end Reid Priedhorskyand Loren Terveen reid@reidster.net http://reidster.net/research/

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Cyclopath revisions 37

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Cyclopath revisions in example: 26edges, 9 notes 37

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

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Reverting revision 2of 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

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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

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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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