Presentation given at WISE 2009, Tenth International Conference on Web Information Systems Engineering, Poznan, Poland, October 2009 ABSTRACT: The emergence of new media technologies in combination with enhanced information sharing functionality oered by the Web provides new possibilities for cross-media annotations. This in turn raises new challenges in terms of how a true integration across dierent types of media can be achieved and how we can develop annotation services that are sufficiently flexible and extensible to cater for new document formats as they emerge. We present a general model for cross-media annotation services and describe how it was used to define an architecture that supports extensibility at the data level as well as within authoring and visualisation tools.

1. An Architecture for
Open Cross-Media Annotation Services
Beat Signer1 and Moira C. Norrie2
1 2
Department of Computer Science Institute for Information Systems
Vrije Universiteit Brussel ETH Zurich
1050 Brussels, Belgium 8092 Zurich, Switzerland
2 December 2005

2. Motivation
Memex Annotea Project
Digital Libraries Cross-media Annotations
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

3. Motivation …
 Existing annotation solutions support the annotation of
a fixed set of multimedia resources
 How easy can those solutions be extended to support
emerging future digital or physical resource types?
 annotation tool should evolve over time
 An open cross-media annotation solution has to provide
extensibility
 on the data level
 on the annotation authoring and access level (user interface)
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

4. What is an Annotation?
 A link in a hypermedia system is defined between an
existing source and target object
 In addition to a link, the definition of an annotation often
includes the content authoring of the annotation object
itself (target object)
 An annotation service therefore can be seen as a
specific application of a more general link service
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

5. Annotation Matrix
# annotation types
open cross-media
 Four existing classes of
annotations annotation systems
 A: single source and single
annotation type
... B2
 B: single source and
D2 multiple annotation types
5
 C: multiple source and
single annotation type
4 B1
 D: multiple source and
D1 multiple annotation types
3
 Proposed open cross-media
2 annotations cover the whole
A1... An C1 C2 C3 space
1
# resource types
1 2 3 4 5 ...
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

6. Annotation Model (RSL Extension)
Annotation Model
Comments Formal Informal
...
Explanations Annotations
i SERVER
RSL Metamodel Links
source target
Users Entities
Layers Selectors Resources
i WEB
XPointer XHTML Docs
i MOVIE
Time Spans Movies
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

7. Annotation Model (RSL Extension) ...
link link link
Navigational Structural (1,*)
Annotations |HasChild|
Links Links
partition
link parameter
(1,*) (1,*) Has (0,*)
HasSource Links HasTarget Preferences Preferences
(0,*) (0,*)
parameter (0,*)
(0,*) (0,*)
Properties HasProperties (0,*)
entity (0,*) AccessibleTo (0,*) user
(0,*)
Entities (1,1) Users HasMembers
contextResolver (0,*)
(0,*)
Context HasResolver CreatedBy
partition
Resolvers (0,*) partition (0,*)
selector resource individual group
(1,1) (0,*)
Selectors RefersTo Resources Individuals Groups
(1,1) (0,*)
layer
(0,*) (0,*)
OnLayer Layers |HasLayers|
B. Signer and M. C. Norrie, As We May Link: A General Metamodel for Hypermedia Systems, in Proc. of ER 2007, Nov 2007
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

8. Data and Visual Plug-in Architecture
Client Application Resource Plug-in Repository
Visual Plug-ins Visual Plug-ins Data Plug-ins
Annotation/Link Annotation/Link
Browser & Editor Service
Visual Plug-ins Data Plug-ins
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

9. Data and Visual Plug-in Architecture …
 Integration of a new resource type includes
 development of a data plug-in
 implementation of a visual plug-in
 registration with the resource plug-in repository
 Annotation/Link browser loads plug-ins on demand
 internal or external (third party application) visualisation
 Third party applications use the annotation/link browser
for annotation visualisation
 similar to the integration of third-party applications with web
browsers
 Non-monolithic annotation model and authoring tool
 resource-specific plug-ins
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

10. Visual Plug-ins
showEntity()
showEntity(), getSelectedEntity()
Annotation/Link Browser & Editor Client Application
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

11. Visual Plug-ins …
 General annotation tool deals only with RSL-specific
data and not with any media-specific details
 create/delete links, user management, …
 Definition of annotation anchors (resources or selectors)
handled by visual plug-ins
 separation of concerns
 Two basic purposes
 rendering of specific resource types (resources and selectors)
 creation and deletion of resources and selectors
 Well defined visual plug-in API
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

12. Conclusions
 Extensible open cross-media annotation solution
 plug-ins loaded on demand
 Separation of concerns between
 annotation model and resource-specific data plug-ins
 annotation tool and resource-specific visual plug-ins
 No distinction between entities that can be used as
sources or annotations
 annotations and links as first-class objects
 Annotation/Link browser and editor can be integrated
with third party applications
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be

13. Further Information
 Beat Signer, Fundamental Concepts for Interactive
Paper and Cross-Media Information Spaces,
ISBN 978-3-8370-2713-6, May 2008
 http://vub.academia.edu/BeatSigner
October 7, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be