The LEMO Annotation Framework
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  • 1. The LEMO Annotation Framework Open Annotations Meeting Berkeley, 10/12/2009 Bernhard Haslhofer Bernhard Haslhofer
  • 2. What is LEMO? • A Web-based, multimedia annotation framework, consisting of • a back-end storage • front-ends for image, audio, and video annotation • Demo at: http://dme.arcs.ac.at/annotation/econnect- annotation-showcase.html Bernhard Haslhofer 2
  • 3. Driving Requirements... 1. objects to be annotated are multimedia ‣ need a uniform model; no content-type specific solution 2. annotations address specific content parts (fragments) ‣ need a uniform fragment identification approach 3. shift towards the Web ‣ need to expose annotation data on the Web (Linked Data) Bernhard Haslhofer 4
  • 4. Reuse of existing standards • Semantic Web standards (RDF/S, OWL, SPARQL) • RESTful Web Service Design • Annotea data model & protocol • XPointer, MPEG-21, SVG, etc. for fragment identification • .... Bernhard Haslhofer 5
  • 5. Why not use Annotea as it is? • Annotea is for the annotation of Web pages; LEMO should also support annotation of embedded content items • Annotea doesn’t assign datatypes to its properties; LEMO uses OWL’s (data)typing features • Annotea doesn’t support multimedia fragment identification; LEMO uses MPEG-21 (multimedia) fragment identification Bernhard Haslhofer 6
  • 6. A Uniform Annotation Model • annotation profiles; cf. application profiles for metadata interoperability • an Annotea-based core model • with content- and annotation-type specific model extensions • implemented as light-weight software components (add-ons) Bernhard Haslhofer 7
  • 7. A Uniform Annotation Model Annotea Annotation Schema: http://www.w3.org/2000/10/annotation-ns# Annotation annotates author body created modified context related subClassOf subPropertyOf subPropertyOf subPropertyOf subPropertyOf subPropertyOf subPropertyOf annotates author label created modified fragment date date any string string Time Time URI Annotation Annotation Core Schema: http://lemo.mminf.univie.ac.at/annotation-core# Key Symbols: RDFS/OWL RDFS OWL OWL XML Schema domain range Class Property ObjectProperty DatatypeProperty Datatype Bernhard Haslhofer 8
  • 8. A Uniform Annotation Model Annotation Relationship Schema: Text Annotation Schema: http://lemo.mminf.univie.ac.at/ann-relationship# http://lemo.mminf.univie.ac.at/ann-text# Relation- Text ship Annotation isLinkedTo title description subClassOf subCla ssOf subPropertyOf subPropertyOf annotates author label created modified fragment date date any string string Time Time URI Annotation Annotation Core Schema: http://lemo.mminf.univie.ac.at/annotation-core# Bernhard Haslhofer 9
  • 9. Uniform Fragment Identification • introduce a fragment element with URI range • follow MPEG-21 media pointer scheme • an annotation can define multiple fragments • URI-encoding of fragments • minimal consensus • content-type specific extensions Bernhard Haslhofer 10
  • 10. Uniform Fragment Identification 12 < rdf : RDF Fragment xmlns : a =" http :// lemo . mminf . univie . ac . at / cation can int annotation - core #" ..." > for all approa ized and wide ... useful to reta <a : annotates > http :// www . univie . ac . at / test . mpg identifier can </ a : annotates > fragment part <a : fragment > http :// www . univie . ac . at / test . mpg # mp (~ time requested res ( ’ npt ’ , ’30 ’ , ’40 ’) ) losing the exa </ a : fragment > relationship t ... By using </ rdf : RDF > improving the representation Listing 1 Time fragment of a video expressed according to lieve, as Geurt the MPEG-21 fragment identification specification tous use of UR interoperable, Bernhard Haslhofer 11 annotations.
  • 11. <a : annotates > http :// www . univie . ac . at / test . mpg identifier can not be processed by a </ a : annotates > fragment part of the respective UR <a : fragment > http :// www . univie . ac . at / test . mpg # mp (~ time requested resource is returned. Wi ( ’ npt ’ , ’30 ’ , ’40 ’) ) losing the exact fragment, this beh </ a : fragment > relationship to the resource as a wh ... By using this simple method in improving the interoperability of fra Uniform Fragment Identification </ rdf : RDF > representations in diverse annotatio Listing 1 Time fragment of a video expressed according to lieve, as Geurts et al [20] have conclu the MPEG-21 fragment identification specification tous use of URIs will help to solve the interoperable, explicit links between annotations. < rdf : RDF xmlns : a =" http :// lemo . mminf . univie . ac . at / annotation - core #" xmlns : x =" http :// lemo . mminf . univie . ac . at / 4.4 Exposing Annotations as Web R annotation - video #" ..." > Since we follow a REST-based appro ... URIs (e.g., http://www.example.o are in fact dereferencable URIs, whi <a : annotates > http :// www . univie . ac . at / test . mpg </ a : annotates > by humans and machines. Therefor <a : fragment > tation framework fulfills the first and http :// www . univie . ac . at / test . mpg # mp (~ time ( ’ npt ’ , ’30 ’ , ’40 ’) ) principles, as described in Section 3 </ a : fragment > To fulfill the third principle, LEM <x : time_fragment xmlns : mpeg21 =" http :// lemo . mminf . univie . ac . at / an not ati on_m peg 21 #" > expose annotation data in different < mpeg21 : uri_fid > http :// www . univie . ac . at / Humans typically access Web resour test . mpg # mp (~ time ( ’ npt ’ , ’30 ’ , ’40 ’) ) which in turn requires an (X)HTM </ mpeg21 : uri_fid > < mpeg21 : time_scheme > npt </ mpeg21 : order to display the returned inform time_scheme > requirement by relying on content n < mpeg21 : start_time >30 </ mpeg21 : start_time > < mpeg21 : end_time >40 </ mpeg21 : end_time > a built-in HTTP feature. Figure 5 il </ x : time_fragment > tations can be retrieved in various fo ... the appropriate mime-type in the H header field. LEMO forwards client r </ rdf : RDF > annotation (e.g., http://example.c Listing 2 Alternative representation within the add-on to the appropriate physical represen model example.com/annotations/html/1 and http://example.com/annotati Bernhard Haslhofer 12 ing an HTTP 303 See Other respon
  • 12. Annotations as Web Resources Resource 1 + URI annotates 0..* Annotation Bernhard Haslhofer 13
  • 13. Annotations as Web Resources Dereference an annotation URI, requesting HTML content GET http://example.com/annotations/1 Accept: text/html 303 See Other Location http://example.com/annotations/html/1 GET http://example.com/annotations/html/1 Client LEMO Accept: text/html 200 OK <HTML> ... </HTML> Dereference an annotation URI, requesting RDF content GET http://example.com/annotations/1 Accept: application/rdf+xml 303 See Other Location http://example.com/annotations/rdf/1 GET http://example.com/annotations/rdf/1 Client LEMO Accept: application/rdf+xml 200 OK <RDF> ... </RDF> Bernhard Haslhofer 14
  • 14. Current LEMO developments • integration into Europeana portal • enhancing multimedia support on user-interface • integration with semi-automatic (multimedia) metadata extraction techniques • investigating adoption of fragment identification working groups recommendations Bernhard Haslhofer 15