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A Semantic Web Content Model and Repository

Max Völkel 6.9.2007 I-Semantics, Graz. A Semantic Web Content Model and Repository. Outline. Motivation Analysis: Web vs. Semantic Web Developing a unified Semantic Web Content Model In three easy steps Implementation. How to model structure + content in one model?. Background

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A Semantic Web Content Model and Repository

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  1. Max Völkel 6.9.2007I-Semantics, Graz A Semantic Web Content Model and Repository

  2. Outline • Motivation • Analysis: Web vs. Semantic Web • Developing a unified Semantic Web Content Model • In three easy steps • Implementation

  3. How to model structure + content in one model? • Background • Wikis, Personal Semantic Wikis, Semantic Desktop, … • Two motivations: • Bring flexibility and expressivity of RDF to the end-user • Allow RDF to model and represent content as well – not only its metadata • Goal: Unified Model • As usable as the web • But how to represent semantics? Semantic queries? • As expressive and as flexible as the semantic web • How to represent binary data (desktop files, web resources) in RDF? • Unified search • “Give me all papers written by author X which contain Y”

  4. Granularity: Gets smaller Web 1.0: homepages, portals Web 2.0: micro-content Renderable representations Freedom of formalisation Less semantic HTML is less portable, but works Analysis: The Web HTTP URI Representation Encoding meta-data ChangeDate MimeType HTML, JPG, CSS, JS, PDF, … HTTP Content

  5. Flexible, very expressive Not expressive enough: Literals cannot be addressed Statements cannot be addressed (but reified) 10 different node types  complex for end-users Exising formal knowledge can be re-used Analysis: The Semantic Web

  6. Requirements for a SWCM • Content granularity • Expressivity • Binary Content • Freedom of formalisation • Human-usable • Renderable representations • Human-type- and memorizable names (e.g. like WikiWords) • Inverse Relations • Knowledge re-use • Standard CMS features: • Access rights  addressable parts • Versioning  addressable parts

  7. Comparison Feature Web Sem. Web Desired • Content granularity mid/large small any • Goal: From small comments to full web pages/files • Expressivity - + ++ • Binary Content ++ ~ ++ • Freedom of formalisation + - + • Human-usable ++ - ++ • Renderable representations • Human-type- and memorizable names (e.g. like WikiWords) • Inverse Relations • Knowledge re-use - ++ + • Standard CMS features: • Access rights  addressable parts + ~ + • Versioning  addressable parts + ~ +

  8. 1 Creating the SWCM: Step 1: A Human-Usable RDF

  9. Step 1: A Human-Usable RDF • Items have a URI and can have a Literal •  Addressable Literals URI Literal 0..1 Item

  10. Step 1: A Human-Usable RDF • Statements connect Items •  Expressivity of RDF URI Literal 0..1 Item source target Statement relation

  11. Step 1: A Human-Usable RDF • Addressable Statements •  Syntactic sugar over reification URI Literal 0..1 Item source target Statement relation

  12. Step 1: A Human-Usable RDF • Address Items via human-type-able name (e.g. WikiWords) •  Human-usable naming URI Literal 0..1 Item source target Statement NameItem relation

  13. Step 1: A Human-Usable RDF • Statements (Item, NameItem, Item) •  Decision that relations should be human-name-able URI Literal 0..1 Item source target Statement NameItem relation

  14. Step 1: A Human-Usable RDF • Relations have always an inverse •  Item-centric rendering easier for tools URI Literal 0..1 Item source target Statement NameItem relation inverse Relation

  15. Step 1: A Human-Usable RDF • A Model contains Items • A Model has a URI Model URI Literal 0..n 0..1 Item source target Statement NameItem relation inverse Relation

  16. 2 Creating the SWCM: Step 2: Include Binary Content

  17. Step 2: Include Binary Content • From addressable literals to addressable representations URI Literal 0..1 Item

  18. Step 2: Include Binary Content URI Representation 0..1 Item

  19. Step 2: Include Binary Content • Representations on the web have some built-in properties • Metadata: Mime-type, encoding, change-date • Data: the actual content itself URI Representation 0..1 Item

  20. Step 2: Include Binary Content • Representations on the web have some built-in properties • Metadata: Mime-type, encoding, change-date • Data: the actual content itself URI Representation Encoding 0..1 ChangeDate Item MimeType Content

  21. Step 2: Include Binary Content • In SWCM, representations have an author • Like in wikis, blogs, web pages, … • Can be „anonymous“ URI Representation Encoding 0..1 ChangeDate Item MimeType Content

  22. Step 2: Include Binary Content • In SWCM, representations have an author • Like in wikis, blogs, web pages, … • Can be „anonymous“ URI Representation Encoding author 0..1 ChangeDate Item MimeType Content

  23. 3 Creating the SWCM: Step 3: Merge Step 1 and Step 2

  24. The Semantic Web Content Model Model URI Representation Encoding author 0..n 0..1 ChangeDate Item source MimeType target Content Statement NameItem relation inverse Relation Structure Content

  25. The Semantic Web Content Model • We expect end-users to understand the circled parts Model URI Representation Encoding author 0..n 0..1 ChangeDate Item source MimeType target Content Statement NameItem relation inverse Relation Structure Content

  26. Implementation

  27. Swecr is implemented in two layers swecr.model interface swecr.core interface

  28. The swecr.model API (see www.swecr.org) www.swecr.org IMimeType 0..n IRepository IModel RDF2Go.URI author IContent ChangeDate 0..n IItem IBinContent INameContent source target 0..1 IContentItem INameItem 1. Content of a INameItem is unique within its IModel. 2. Mimetype always = „text/plain“ IStatement IRelaton inverse

  29. swecr.core

  30. Swecr.core: Some Content stored in RDF www.swecr.org :FZI a swcm:NameItem , swcm:Item ;swcm:hasChangeDate "2007-08-24T16:07:29Z"^^xsd:dateTime ;swcm:hasContent “FZI Forschungszentrum Informatik" . :employs a swcm:NameItem , swcm:Item , swcm:Relation ;swcm:hasAuthor swcm:anonymous-author ;swcm:hasChangeDate "2007-08-24T16:07:32Z"^^xsd:dateTime ;swcm:hasContent “employs" ;swcm:hasInverse :employedBy . :worksFor a swcm:NameItem , swcm:Item , swcm:Relation ;swcm:hasAuthor swcm:anonymous-author ;swcm:hasChangeDate "2007-08-24T16:07:33Z"^^xsd:dateTime ;swcm:hasContent “works for" ;swcm:hasInverse :employs .

  31. Implemented in two layers www.swecr.org <urn:rnd:-1d72b0a2:11498a0d25f:-7fff>a swcm:Item , swcm:Statement ;swcm:hasChangeDate "2007-08-24T16:07:30Z"^^xsd:dateTime ;swcm:stmtRelation :employs ;swcm:stmtSource :FZI ;swcm:stmtTarget :Max . • Statements stored in two RDF models: user model and index model  Query answering :FZI :employs :Max . :Max :worksFor :FZI . redundant

  32. ModelSetImpl But where to store binaries? www.swecr.org swecr.model interface swecr.core interface RDF ModelSet ? user model index model

  33. BinStore – a simple binary store www.swecr.org • Intuition: The simplest web-like API, that would possibly work (and allow random-access) • Data model: URI  Metadata + InputStream / OutputStream • Simple implementation on files • Future: Consider JCR • getReadHandle • InputStream readStream(); • getMimeType(), getSize() • getWriteHandle • writeStream( InputStream, MimeType ) • setMimeType( MimeType ) • getRandomAccessHandle • delete( URI ) Binary Store BinStoreImpl API

  34. BinStoreImpl ModelSetImpl Persistence in an RDF ModelSet and a Binary Store www.swecr.org • Full text queries need a full text index swecr.model interface swecr.core interface RDF ModelSet Binary Store user model index model

  35. The complete swecr.core www.swecr.org swecr.model interface swecr.core interface RDF ModelSet Binary Store Query Engine BinStoreImpl IndexingModelSet IndexingBinStore ModelSetImpl TextIndexImpl Bin2Text(Aperture) AdapterServer Existing component In progress Download from www.swecr.org

  36. Example: Wiki-page • Example: A wiki-page in SWCM • Title of wiki page  NameItem • Content of wiki page  Item • Relation between title and page content  Statement • Who uses it? • WavesWiki (part of BMBF project, http://waves.fzi.de) • SemFS a Semantic File System (presented at I-KNOW in 2006) • Conceptual Data Structures (end-user personal KM tool) • Interest from XWiki and Cognium Systems

  37. SWCM is a content management model combining the usability of the web with the expressivity and flexibility of the semantic web Summary Item source target Statement NameItem inverse relation Future Work: • Refactor core layer into smaller parts (services) • Create RDF with binaries – API • Unified queries (like the LuceneSAIL or LARQ) • Crawling of external resources (index localled, stored remote) • From structured text to SWCM models (see paper) Relation

  38. Thank You.

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