1 / 20

Module 2b: Modeling Information Objects and Relationships

Module 2b: Modeling Information Objects and Relationships. IMT530: Organization of Information Resources Winter, 2008 Michael Crandall. Recap. Information storage and retrieval systems (ISARs) are part of a larger knowledge system

shana
Download Presentation

Module 2b: Modeling Information Objects and Relationships

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Module 2b: Modeling Information Objects and Relationships IMT530: Organization of Information Resources Winter, 2008 Michael Crandall

  2. Recap • Information storage and retrieval systems (ISARs) are part of a larger knowledge system • Within an ISAR, two inputs (user needs and entities) are combined to produce an answer for the user’s question • To make that happen, both user’s queries and information entities need to be represented in some way IMT530B Organization of Information Resources

  3. Module 2b Outline • Models • The entity-relationship model for database design • Resource Description Framework for the web • Syntax vs. semantics • Ontologies and their place IMT530B Organization of Information Resources

  4. What is a Model? • A model represents a particular view of reality through a systematic set of rules • As you’ve seen with vocabularies, a representation is only that, not reality • In information systems, we are attempting to represent objects and their relationships • This can become very complex, very quickly • A way to manage this complexity is critical for success • Models allow multiple systems to interact and share information more effectively • Think of the earlier slide showing MSWeb’s search service- outside sources sharing the same model can provide much richer information to the system (and ultimately the users) IMT530B Organization of Information Resources

  5. Sources of Models • Database world • Entity-relationship model • Programming world • Object oriented programming • Information science world • Functional Requirements for Bibliographic Records • Dublin Core • Web world • Resource Description Framework • Ontology Web Language IMT530B Organization of Information Resources

  6. Database Modeling • Chen developed concept of entities and relationships • Entities are “things which can be described” • Relationships are “associations between entities” • These have attributes which are instantiated in values • Allows description of complex spaces through diagrams showing how entities relate to other entities (tuples) • Represented in tables within databases • Essential in relational database modeling IMT530B Organization of Information Resources

  7. Example of E-R Model From Chen, 1985 IMT530B Organization of Information Resources

  8. How RDF Works • RDF is based on the idea that • Things being described (the Subject) • Have properties (the Predicate), • Which have values (the Object) • And that resources can be described by making statements that specify those properties and values (triples) • RDF models statements as nodes and arcs in a graph. In this notation, a statement is represented by: • a node for the subject • a node for the object • an arc for the predicate, directed from the subject node to the object node. IMT530B Organization of Information Resources

  9. How RDF Works • This is done using URIs (Uniform Resource Identifiers) that can be created to refer to anything that needs to be referred to in a statement, including • network-accessible things, such as an electronic document, an image, a service (e.g., "today's weather report for Los Angeles"), or a group of other resources. • things that are not network-accessible, such as human beings, corporations, and bound books in a library. • abstract concepts that do not physically exist, such as the concept of a "creator". IMT530B Organization of Information Resources

  10. An Example http://www.example.org/index.html has a creator whose value is John Smith could be represented by an RDF statement having: • a subject http://www.example.org/index.html • a predicate http://purl.org/dc/elements/1.1/creator • and an object http://www.example.org/staffid/85740 IMT530B Organization of Information Resources

  11. Example of RDF Model Figure 1: An RDF Graph Describing Eric Miller IMT530B Organization of Information Resources

  12. RDF in XML <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#"> <contact:Person rdf:about="http://www.w3.org/People/EM/contact#me"> <contact:fullName>Eric Miller</contact:fullName> <contact:mailbox rdf:resource="mailto:em@w3.org"/> <contact:personalTitle>Dr.</contact:personalTitle> </contact:Person> </rdf:RDF> IMT530B Organization of Information Resources

  13. Syntax vs. Semantics • Note that models are distinct from the language used to represent them • An RDF model can be written in XML, but is independent of the language • The reason XML becomes important is for machine to machine communication • Allows recognition of structures and semantics in a common way, promoting interoperability at the syntax level • Semantics are controlled by the model • Different models may not communicate even if you’re using XML • So defining and standardizing your semantic model is critical for true interoperability IMT530B Organization of Information Resources

  14. Ontologies • Semantic web is next step to embed semantics in syntax- but you need to model namespaces to do this • Rich namespaces are being modeled through ontologies- an extension of classification theory that includes many more relationship types • Qin and Paling on advantages of ontology • Higher levels of conception of descriptive vocabulary • Deeper semantics for class/subclass and cross-class relationships • Ability to express such concepts and relationships in a description language • Reusability and share-ability of the ontological constructs in heterogeneous systems • OWL (Web Ontology Language) is current favorite tool (http://www.w3.org/TR/owl-features/) IMT530B Organization of Information Resources

  15. Ontology Example • http://www.aiai.ed.ac.uk/project/enterprise/enterprise/ontology.html IMT530B Organization of Information Resources

  16. Questions?? • And then a break…. IMT530B Organization of Information Resources

  17. Exercise 2b • Assemble your group • Spend 45 minutes working through the examples in Exercise 2b • Ask questions and talk!!! • Be sure to hand in completed work at the end of class for credit!!! IMT530B Organization of Information Resources

  18. <!--RDF Model 1--> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:eg="http://example.org/foovocab#" xmlns:foaf="http://xmlns.com/foaf/0.1/"> <foaf:Person rdf:nodeID="p1"> <foaf:name>Alice</foaf:name> <foaf:knows rdf:nodeID="p2"/> <eg:acquaintance rdf:nodeID="p2"/> <eg:archNemesis rdf:nodeID="p2"/> </foaf:Person> <foaf:Person rdf:nodeID="p2"> <foaf:name>Bob</foaf:name> <eg:secretlyStalking rdf:nodeID="p1"/> </foaf:Person> </rdf:RDF> <!--RDF Model 2--> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:eg="http://example.org/foovocab#" xmlns:foaf="http://xmlns.com/foaf/0.1/"> <foaf:Person rdf:nodeID="bob"> <!--Same elements--> <foaf:knows rdf:nodeID="carol"/> <foaf:name>Bob</foaf:name> <foaf:homepage rdf:resource="http://students.washington.edu/parko/" /> <foaf:mbox_sha1sum>241021fb0e6289f92815fc210f9e9137262c252e</foaf:mbox_sha1sum> </foaf:Person> <foaf:Person rdf:nodeID="carol"> <foaf:name>Carol</foaf:name> </foaf:Person> </rdf:RDF> <!--RDF Integrate Model 3--> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:eg="http://example.org/foovocab#" xmlns:foaf="http://xmlns.com/foaf/0.1/"> <foaf:Person rdf:nodeID="p1"> <foaf:name>Alice</foaf:name> <foaf:knows rdf:nodeID="p2"/> <eg:acquaintance rdf:nodeID="p2"/> <eg:archNemesis rdf:nodeID="p2"/> </foaf:Person> <foaf:Person rdf:nodeID="p2"> <foaf:name>Bob</foaf:name> <foaf:knows rdf:nodeID="carol"/> <foaf:homepage rdf:resource="http://students.washington.edu/parko/" /> <foaf:mbox_sha1sum>241021fb0e6289f92815fc210f9e9137262c252e</foaf:mbox_sha1sum> <eg:secretlyStalking rdf:nodeID="p1"/> </foaf:Person> <foaf:Person rdf:nodeID="carol"> <foaf:name>Carol</foaf:name> </foaf:Person> </rdf:RDF> Example of Integration Contributed by Oknam Park IMT530B Organization of Information Resources

  19. Modeling Wrapup • One model will not fit all needs • More and more, integration of web models with database and programming models is becoming important • Each will provide a different view of the world you are trying to manage • Finding linkages for interoperability is the big challenge • We’ll look next week at some current attempts in this area • Think about how you would approach these problems and see how it fits what you read IMT530B Organization of Information Resources

  20. Next Week • We’ll hear from a guest speaker about commercial use of ontologies • We’ll dive into metadata schemas and schemes and the world of standards • Remember to read next week’s assignments BEFORE class • Have a great weekend!! IMT530B Organization of Information Resources

More Related