Open Annotation: Technical Overview                                   h"p://www.openannota-on.org/
                       ...
Outline•  Motivation•  OAC’s Perspective on Annotations•  Design Choices•  Alpha 3 Data Model                      Open An...
Motivation (1)•  Annotations are a core ingredient of scholarship:    •  Transcribe and annotate medieval manuscripts;    ...
Motivation (2)•  Existing solutions for scholarly annotation are repository-centric, tied   to silos:    •  Annotation in ...
Open Annotation Collaboration•  Focus on interoperability for annotations in order to allow sharing of   annotations acros...
OAC’s Perspective on Annotations (1)•  The following characterize an annotation:    •    There is an author (human, softwa...
OAC’s Perspective on Annotations (2)•  Body and target of an annotation can be of any media type.   •  A video can annotat...
OAC’s Perspective on Annotations (3)•  Most (scholarly) annotations involve parts of resources (image   regions, slices of...
Design Choices (1)•  Interoperability specified in terms of the Architecture of the Web (URI,   link, resource, representa...
Design Choices (2)•  Client autonomy.   •  Not an annotation protocol (cf. Annotea) but an annotation model      combined ...
Protocolpublish, subscribe, consume   Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel   11
Publish/Subscribepublish   subscribe                                 consume            Open Annotation: Technical Overvie...
Design Choices (3)•  An annotation is an information resource (aka document).   •  Earlier versions of the model regarded ...
Design Choices (4)•  Significant attention to problems related to the ephemeral nature of the   Web.•  Representations of ...
Design Choices (5)•  A model that gracefully builds from simple to complex•  The simple core of the model supports element...
Basic Model•  The basic model has three resources:    •  Annotation (an RDF document)         •  Default: RDF/XML but othe...
Basic Model Example  Open Annotation: Technical OverviewRobert Sanderson, Herbert Van de Sompel   17
Additional Relationships and Properties•  Any of the resources can have additional information attached,such as creator, d...
Additional Properties Example      Open Annotation: Technical Overview    Robert Sanderson, Herbert Van de Sompel   19
Annotation Types•  There can be further types of Annotation, such as a Reply.•  Example: Replies are Annotations on Annota...
Annotation Types Example    Open Annotation: Technical Overview  Robert Sanderson, Herbert Van de Sompel   21
Annotation Types ExampleWell come back to      these …                         Open Annotation: Technical Overview        ...
Inline Information•  It is important to be able to have content contained within theAnnotation document for reasons of Cli...
Inline Information: Body•  We introduce a resource identified by a non resolvable URI, suchas a UUID URN, as the Body.•  W...
Inline Body Example  Open Annotation: Technical OverviewRobert Sanderson, Herbert Van de Sompel   25
Multiple Targets•  There are many use cases for multiple targets for an Annotation:     •  Comparison of two or more resou...
Multiple Targets Example    Open Annotation: Technical Overview  Robert Sanderson, Herbert Van de Sompel   27
Segments of Resources•  Most annotations are about part of a resource•  Different segments for different media types:    •...
Segments of Resources (2)•  Web Architecture Segmentation:    •  A URI with a Fragment identifies part of the resource    ...
Segments of Resources: Fragment URIs•  URI Fragments are a syntax for creating subsidiary URIs thatidentify part of the ma...
Segments of Resources: Media Fragments•  Media Fragments allow anyone to create URIs that identify partof an image, audio ...
Media Fragments Example    Open Annotation: Technical Overview  Robert Sanderson, Herbert Van de Sompel   32
Media Fragments Example    Open Annotation: Technical Overview  Robert Sanderson, Herbert Van de Sompel   33
Complex Constraints•  If a Fragment URI is not possible, we introduce a Constraint todescribe the segment of interest     ...
Constraint Example  Open Annotation: Technical OverviewRobert Sanderson, Herbert Van de Sompel   35
Inline Information: Constraints•  We can also use inline information in the same way as for the Bodyresource to include th...
Inline Constraint Example    Open Annotation: Technical Overview  Robert Sanderson, Herbert Van de Sompel   37
RDF Constraints•  Instead of having the information in an external document, it could bewithin the RDF of the Annotation d...
RDF Constraint Example   Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel   39
RDF Constraint plus Media Fragment         Open Annotation: Technical Overview       Robert Sanderson, Herbert Van de Somp...
Constrained Body•  The body may also be constrained in the same way as Targets                       Open Annotation: Tech...
Constrained Body  Open Annotation: Technical OverviewRobert Sanderson, Herbert Van de Sompel   42
Annotating a Non-Document•  The Target of an Annotation does not have to be a document:     can be a Non Information Resou...
Non Information Resource Example        Open Annotation: Technical Overview      Robert Sanderson, Herbert Van de Sompel  ...
Annotations and Time•  Web Resources change over time, but keep the same URI•  This is important for linking, but makes An...
Web-Centric Annotation: No PersistenceGoogle Sidewiki Annotation on http://news.bbc.co.uk/ as of 2010-06-14               ...
Web-Centric Annotation: No Annotations                       Archived page from:http://www.dracos.co.uk/work/bbc-news-arch...
Web-Centric Annotation: Desired Cross-Linking              Open Annotation: Technical Overview            Robert Sanderson...
Annotations and Time•  There are three different types of Annotation with respect toTime:    •  Timeless Annotations      ...
Timeless Annotations•  The model for a Timeless Annotation is the base model                       Open Annotation: Techni...
Uniform Annotations•  If the same time is applicable to all resources, we attach it to theAnnotation using the oac:when pr...
Uniform Annotation Example     Open Annotation: Technical Overview   Robert Sanderson, Herbert Van de Sompel   52
Varied Annotations•  If different timestamps are required for each resource, we useoac:when from an oac:TimeConstraint.   ...
Varied Annotation Example     Open Annotation: Technical Overview   Robert Sanderson, Herbert Van de Sompel   54
http://www.openannotation.org/http://groups.google.com/group/oac-discuss            Open Annotation: Technical Overview   ...
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OAC Technical Summary

  1. 1. Open Annotation: Technical Overview h"p://www.openannota-on.org/
 h"p://groups.google.com/group/ oac‐discuss
 Robert
Sanderson






 Herbert
Van
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 Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel
  2. 2. Outline•  Motivation•  OAC’s Perspective on Annotations•  Design Choices•  Alpha 3 Data Model Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 2
  3. 3. Motivation (1)•  Annotations are a core ingredient of scholarship: •  Transcribe and annotate medieval manuscripts; •  Annotate maps with maps; •  Annotate video recording of endangered languages with non- verbal communication events; •  Annotate 3D museum artifacts; •  Your use cases … Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 3
  4. 4. Motivation (2)•  Existing solutions for scholarly annotation are repository-centric, tied to silos: •  Annotation in terms of specific repository and/or collection, no global scope; •  Only consumable in client/server combination that created the annotation; •  Annotations not shareable beyond original server – can not create cross system services based on (enriched & merged) annotations. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 4
  5. 5. Open Annotation Collaboration•  Focus on interoperability for annotations in order to allow sharing of annotations across: •  Annotation clients; •  Content collections; •  Services that leverage annotations.•  Focus on annotation for scholarly purposes. But desire to make the OAC framework more broadly usable. •  In order to gain adoption => tools, communities, integration of scholarly communication with other areas of discourse. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 5
  6. 6. OAC’s Perspective on Annotations (1)•  The following characterize an annotation: •  There is an author (human, software agent) of an annotation; •  The annotation occurs at some point in time; •  There is a body of an annotation; •  There is a target of an annotation; •  The body annotates the target, i.e. the body is somehow “about” the target. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 6
  7. 7. OAC’s Perspective on Annotations (2)•  Body and target of an annotation can be of any media type. •  A video can annotate a Web page; a Web page can annotate a video. •  This is contrary to the prevailing view in which the body is textual.•  Annotation, body, and target can have different authors. •  This is contrary to the prevailing view in which annotation and body have same authorship. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 7
  8. 8. OAC’s Perspective on Annotations (3)•  Most (scholarly) annotations involve parts of resources (image regions, slices of a video, dimensions of a dataset). •  The annotation framework should provide support for resource segment identification and description.•  A variety of more complex annotations involve multiple targets (and maybe multiple bodies?). •  The annotation framework should support this. •  So far, no compelling use cases for multiple bodies have been identified. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 8
  9. 9. Design Choices (1)•  Interoperability specified in terms of the Architecture of the Web (URI, link, resource, representation, …) , Semantic Technologies, Linked Data. •  Aligned with desire to more tightly embed scholarly communication in overall human discourse; •  Aligned with trend towards machine-actionable scholarly communication system; •  Aligned with approach we followed in other efforts (OAI-ORE for Aggregations; Memento for versioning). Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 9
  10. 10. Design Choices (2)•  Client autonomy. •  Not an annotation protocol (cf. Annotea) but an annotation model combined with a publish/subscribe mechanism; •  No reliance on a server that helps with generation of annotations. Only a server that supports publish/discovery of the annotation created by the client is assumed. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 10
  11. 11. Protocolpublish, subscribe, consume Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 11
  12. 12. Publish/Subscribepublish subscribe consume Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 12
  13. 13. Design Choices (3)•  An annotation is an information resource (aka document). •  Earlier versions of the model regarded annotations as conceptual, non-information resources. This approach was related to: •  Ideas to model annotations as events; •  Ideas to model annotations as OAI-ORE Aggregations. •  Community feedback to this approach was negative: •  Added complexity without added value; •  The use of OAI-ORE, and especially its Proxies, was deemed artificial. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 13
  14. 14. Design Choices (4)•  Significant attention to problems related to the ephemeral nature of the Web.•  Representations of URI-addressable resources change over time, resulting in ambiguous or incorrect annotations, as well as annotations that lack (representations of) body and/or target.•  The approach provides hooks to allow: •  Recognizing ambiguous/incorrect annotations, e.g. via timestamp and fixity for body and target; •  Reconstructing the annotation, e.g. via timestamps, scholarly archives, and Memento. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 14
  15. 15. Design Choices (5)•  A model that gracefully builds from simple to complex•  The simple core of the model supports elementary annotation use cases.•  The model becomes gradually more complex to accommodate increasingly complex use cases. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 15
  16. 16. Basic Model•  The basic model has three resources: •  Annotation (an RDF document) •  Default: RDF/XML but others via Content Negotiation •  Body (the comment or text of the annotation) •  Target (the resource the body is about) Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 16
  17. 17. Basic Model Example Open Annotation: Technical OverviewRobert Sanderson, Herbert Van de Sompel 17
  18. 18. Additional Relationships and Properties•  Any of the resources can have additional information attached,such as creator, date of creation, title, etc. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 18
  19. 19. Additional Properties Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 19
  20. 20. Annotation Types•  There can be further types of Annotation, such as a Reply.•  Example: Replies are Annotations on Annotations. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 20
  21. 21. Annotation Types Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 21
  22. 22. Annotation Types ExampleWell come back to these … Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 22
  23. 23. Inline Information•  It is important to be able to have content contained within theAnnotation document for reasons of Client Autonomy: •  Clients may be unable to mint new URIs for every resource •  Clients may wish to transmit only a single document•  Third parties can generate new URIs if the client does not•  The W3C has a Content in RDF specification that describes howto do this: •  http://www.w3.org/TR/Content-in-RDF10/ Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 23
  24. 24. Inline Information: Body•  We introduce a resource identified by a non resolvable URI, suchas a UUID URN, as the Body.•  We then embed the data within the Annotation document usingthe chars property from the Content in RDF ontology. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 24
  25. 25. Inline Body Example Open Annotation: Technical OverviewRobert Sanderson, Herbert Van de Sompel 25
  26. 26. Multiple Targets•  There are many use cases for multiple targets for an Annotation: •  Comparison of two or more resources •  Making a statement that applies to all of the resources •  Showing the provenance of resources •  Making a statement about multiple parts of a resource•  The OAC Data Model allows for multiple targets by simply havingmore than one hasTarget relationship. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 26
  27. 27. Multiple Targets Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 27
  28. 28. Segments of Resources•  Most annotations are about part of a resource•  Different segments for different media types: •  Text: paragraph, arbitrary span of words •  Image: rectangular or arbitrary shaped area •  Audio: start and end time points, track name/number •  Video: area and time points •  Other: slice of a data set, volume in a 3d object, … Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 28
  29. 29. Segments of Resources (2)•  Web Architecture Segmentation: •  A URI with a Fragment identifies part of the resource •  Media-specific fragment identifiers; eg XPointer for XML •  W3C Media Fragments URI specification for simple segments of media: http://www.w3.org/TR/media-frags/•  We introduce a method of constraining resources: •  Introduce an approach for arbitrarily complex segments that cannot be expressed using Fragments •  Can be applied to Body or Target resource Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 29
  30. 30. Segments of Resources: Fragment URIs•  URI Fragments are a syntax for creating subsidiary URIs thatidentify part of the main resource•  The syntax is defined per media type •  X/HTML: The named anchor or identified element •  http://www.example.net/foo.html#namedSection •  XML: An XPointer to the element(s) •  http://www.example.net/foo.xml#xpointer(/a/b/c) •  PDF: Many options, most relevant two operations: •  http://www.example.net/foo.pdf#page=2&viewrect=20,80,50,60 •  Plain Text: Either by character position or line position: •  http://www.example.net/foo.txt#char=0,10 •  http://www.example.net/foo.txt#line=1,5 Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 30• :
  31. 31. Segments of Resources: Media Fragments•  Media Fragments allow anyone to create URIs that identify partof an image, audio or video resource.•  The most common case is for rectangular areas of images: •  http://www.example.org/image.jpg#xywh=50,100,640,480•  Link to the full resource as well, for all Fragment URIs Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 31
  32. 32. Media Fragments Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 32
  33. 33. Media Fragments Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 33
  34. 34. Complex Constraints•  If a Fragment URI is not possible, we introduce a Constraint todescribe the segment of interest •  Media Fragments embed the segment description in the URI •  Constraints are entire resources, so can be more expressive •  Constraints may also describe contextual information•  The ConstrainedTarget(CT-1) identifies thesegment of interest•  The type of descriptionis dependent on themedia type and nature ofthe target resource. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 34
  35. 35. Constraint Example Open Annotation: Technical OverviewRobert Sanderson, Herbert Van de Sompel 35
  36. 36. Inline Information: Constraints•  We can also use inline information in the same way as for the Bodyresource to include the Constraint data. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 36
  37. 37. Inline Constraint Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 37
  38. 38. RDF Constraints•  Instead of having the information in an external document, it could bewithin the RDF of the Annotation document.•  We attach information to theConstraint node•  The Annotation Ontologymodels its "Selectors" in thiswayhttp://code.google.com/p/annotation-ontology/ Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 38
  39. 39. RDF Constraint Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 39
  40. 40. RDF Constraint plus Media Fragment Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 40
  41. 41. Constrained Body•  The body may also be constrained in the same way as Targets Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 41
  42. 42. Constrained Body Open Annotation: Technical OverviewRobert Sanderson, Herbert Van de Sompel 42
  43. 43. Annotating a Non-Document•  The Target of an Annotation does not have to be a document: can be a Non Information Resource•  Non Information Resource as Target •  Annotations about: •  Concepts •  Physical things •  Locations •  or any other non-document •  Example: A video about a real life painting•  Non Information Resource as Body •  Well come back to this… Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 43
  44. 44. Non Information Resource Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 44
  45. 45. Annotations and Time•  Web Resources change over time, but keep the same URI•  This is important for linking, but makes Annotation hard. We needto know when the annotation applies to the resource.•  This is true for Body and Target(s).•  The created time is not sufficient, as the Annotation, Body andTarget could be created at different times. The Body could beabout a previous state of the Target. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 45
  46. 46. Web-Centric Annotation: No PersistenceGoogle Sidewiki Annotation on http://news.bbc.co.uk/ as of 2010-06-14 Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 46
  47. 47. Web-Centric Annotation: No Annotations Archived page from:http://www.dracos.co.uk/work/bbc-news-archive/2010/03/08/07.05.html Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 47
  48. 48. Web-Centric Annotation: Desired Cross-Linking Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 48
  49. 49. Annotations and Time•  There are three different types of Annotation with respect toTime: •  Timeless Annotations •  These are always relevant, regardless of the current state of the resource. •  Uniform Annotations •  There is a single timestamp at which all of the resources should be considered. •  Varied Annotations •  Each of the resources (Body, Targets) should be considered at a different time. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 49
  50. 50. Timeless Annotations•  The model for a Timeless Annotation is the base model Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 50
  51. 51. Uniform Annotations•  If the same time is applicable to all resources, we attach it to theAnnotation using the oac:when predicate. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 51
  52. 52. Uniform Annotation Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 52
  53. 53. Varied Annotations•  If different timestamps are required for each resource, we useoac:when from an oac:TimeConstraint. Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 53
  54. 54. Varied Annotation Example Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 54
  55. 55. http://www.openannotation.org/http://groups.google.com/group/oac-discuss Open Annotation: Technical Overview Robert Sanderson, Herbert Van de Sompel 55

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