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  1. 1. Project: ozr (Ontology visualiZeR) Course: WADE (Web Application DEvelopment) Taught by: Conf. PhD. Sabin. C. Buraga Supervisor: Conf. PhD. Lenuta Alboaie Students: Lamasanu Ion Cercel Alexandru Faculty of Informatics, Iasi Distributed Systems, year 2, 1st semester
  2. 2. • What is the domain of this project? => Mostly Semantic Web • Semantic Web: its aim is to convert the current web dominated by unstructured and semi-structured documents into a "web of data" by annotating data with semantic metadata in order to encode data meaning.
  3. 3. Project requirements • Create a web application which can generate and display ontology visualizations conforming to VOWL. • Create and publish a REST service which can generate and service ontology visualizations as raster/vector graphics and also as HTML 5 with embedded RDFa. • The solution must use recent technologies from Social Web and/or Semantic Web.
  4. 4. Web Technologies used 1/3 • RDF (Resource Description Framework): is the foundation of the Semantic Web and is used in order to attach metadata to Web resources and specify relationships between them. RDF goal is to obtain a distributed database model for the Web. RDF data model is based on triples (subject, predicate, object) combined in graphs, is monotone, uses URIs for resource identification. RDF can be serialized into a range of different file formats: RDF-XML, Turtle, N3. • RDFa (RDF attributes): a set of attribute level extensions to HTML, XHTML and various XML based document types and is used for embedding metadata within Web documents. Initially: XHTML with RDF.
  5. 5. Web Technologies used 2/3 • RDF Schema (RDF Vocabulary Description Language): defines a data model for the creation of RDF statements. It allows definitions of classes, properties and restrictions, hierarchies (sub classes and super classes, sub properties and super properties) • SPARQL (SPARQL Protocol and RDF Query Language): is a protocol (via HTTP), query language for RDF datasets (graph traversal) and an XML output format specification (for results). It is inspired by SQL. • Vocabularies: provide lists (and definitions) of common terms that can be used to describe the contents of a dataset.
  6. 6. Web Technologies used 3/3 • Ontologies: are vocabularies that record the logical relationships between terms. • OWL: is a family of knowledge representation languages for authoring ontologies. The languages are characterized by formal semantics and RDF/XML-based serializations for the Semantic Web. It uses some elements from RDF Schema.
  7. 7. What is VOWL? • VOWL = Visual Notation for OWL Ontologies • Considered version: http://purl.org/vowl/v1/, i.e. specification of Version 1.0 - 28 January 2013 • It provides graphical representations for elements of the Web Ontology Language (OWL). • Visual Notation: • Classes = circles (size indicates the connectivity of a class) • Individuals = sections in the circles • Properties = lines/arcs (with different arrow heads, line types, etc.) • Literals, data types and values = rectangles • VOWL distinguishes between 3 layers that may be visualized: • Conceptual Layer: Represents the classes, properties, and their relationships • Instance Layer: Represents the individuals and their relationships • Integrated Layer: Represents the classes populated with individuals
  8. 8. Graphical representations of OWL elements 1/2
  9. 9. Graphical representations of OWL elements 2/2
  10. 10. Design • Demo result:
  11. 11. Requirements analysis • Customer requires a web application and a REST service for generating visualization for a given ontology.
  12. 12. Solution architecture 1/3 The web service can embody the main application logic. • • • • • • • • • INPUT Visualization layer String (one of three): conceptual, instance or integrated Visualization type (one of the following) SVG, PNG, JPG, HTML5RDFa Ontology sample data (ontology profile) => for instance and integrated layer URL / RDF Representation Ontology => for conceptual layer URL / RDF Representation Selected individual => for integrated layer URL / SPARQL query • • • • • OUTPUT Can be one of the following, depending on the desired visualization type image/svg+xml image/png image/jpeg application/xhtml+xml • • The web service will be implemented as a REST service with the following API: Service will be accessible at: http://purl.org/net/ozr2013/viz
  13. 13. Solution architecture 2/3 • • • • • Input parameters: layer = <string> (conceptual | instance | integrated) type = <string> (SVG | PNG | JPG | HTML5RDFa) ontology = URL | RDF Representation (only for conceptual layer) profile = URL | RDF Representation (for instance and integrated layer only) selection = URL | SPARQL query (only for integrated layer) • • Access methods and parameter restrictions: GET (considers ontology and profile parameters values as URLs) POST (considers ontology and profile parameters values as RDF Representations) • • • Input parameters constraints: When conceptual layer is chosen the ontology parameter is mandatory while profile and selection parameters are ignored. When integrated layer is chosen the profile and selection are mandatory and ontology parameter is ignored. When instance layer is chosen the profile is mandatory and ontology and selection parameters are ignored.
  14. 14. Solution architecture 3/3 Syntax Error: • When restrictions and/or constraints are not met the service will respond with (400) Error. • The web application will act as a client by sending requests to the web service and getting output from it as visualizations under requested format. • • • • • • • • Structural Behavioral Functional Non functional Performance Design Derived Allocated
  15. 15. Project code repository • https://students.info.uaic.ro/infoiasi/svn/
  16. 16. Use case • The user will call the Rest service, which will create and publish the ontology visualization. • The Rest service will allow user to select display type(SVG or raster) for visualization.