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KNOWLEDGE REPRESENTATION Ontologies

Communication – Network Management Technologies. KNOWLEDGE REPRESENTATION Ontologies. Rashid Mijumbi Barcelona, April 2011. Data and Information Models Definition. A model is a representation of the entities in a managed environment.

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KNOWLEDGE REPRESENTATION Ontologies

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  1. Communication – Network Management Technologies KNOWLEDGE REPRESENTATION Ontologies Rashid Mijumbi Barcelona, April 2011

  2. Data and Information Models Definition • A model is a representation of the entities in a managed environment. • Provides a common terminology for representing management information, relationships, constraints, rules, and operations to specify data syntax for a chosen domain of discourse Concrete model (for implementors) – Low Level Representation – More Details Conceptual/Abstract model for designers and operators – High Level Representation IM 1 DM 3 DM 2 DM 1

  3. Data Models (1) The “Necessary Evil” • Heterogeneity in systems makes different Data Models a necessity N Different Technologies IPsec VPN MPLS VPN MPLS – TE MPLS – QoS Translation Layer Atleast N*M translations needed Specific Device Model Specific Device Model Specific Device Model Specific Device Model Specific Device #3 Specific Device #2 Specific Device #4 Specific Device #1 M Devices

  4. Data Models (2) Problems Data harmonisation problem in Data Models Security Application Customer Name: rmijumbi Billing Application Customer Name: rashid.mijumbi Fault Management Application Customer Name: mrashid

  5. Enterprise wide managed objects define data Information Models (1) Abstraction, Data Harmonised (no Conflicts) Platform, language and protocol dictate vendor-independent possibilities Information Model 1 : N Vendor implementations dictate working implementation Standards – Based Data Model 1 : M Vendor – Based Data Model

  6. Information Models (2) Router Configuration Example Router(config)# router bgp autonomous-system Router(config-router)# neighbor { ip-address | peer-group-name} remote-as number Router(config-router)# neighbor ip-address activate DEFINING BGP PEERS CISCO • Different Languages • Different Semantics • Different programming models routing-instances { routing-instance-name { protocols { bgp { group group-name; { peer-as as-number; neighbor ip-address; } } } } } Juniper

  7. Ontologies (1)

  8. Ontologies (2) • Ontology refers to the shared understanding of some domain of interest which may be used as a unifying framework – Uschold and Gruininger (1996) • An ontology is an explicit specification of a conceptualisation. – Gruber 1993 • Ontologies offer a formal mechanism for defining an understanding of data • Ontological Commitments • Ontology Requirements: Clarity, Coherence, Extensibility, Minimal encoding bias, Minimal ontological commitment

  9. Ontology Languages • An ontology language is made up of three components • syntax, • semantics (model theory), • proof theory. • The syntax of an ontology language is itself divided into three areas • Logic lexicon, non-logic lexicon and Grammar. • By Syntax • CycL and KIF are examples of languages that support expressions in first-order logic. • By Structure • These languages use a markup scheme to encode knowledge, most commonly XML. • Ontology Inference Layer (OIL), OWL.

  10. Ontology Tools • Ontology development tools • Ontology development tools can be further distinguished as: those that are independent of an ontology language, and those that are tightly dependent on one. • Protégé, Ontolingua. • Ontology merging tools • PROMPT, Chimaera.

  11. Semantic Web (1) • A new form of web content that is meaningful to computers - Berners-Lee 2001 UsedCars Website User • <car> • <location>Hospitalet</location> • <price>€400</price> • <colour>maroon</colour> • <description>Old banger</description> • <model>Ford Escort</model> • </car> This is because computers cannot process the semantics that are associated with web content • User lives in Barcelona and wants to buy a car locally. He can afford up to £500. He wants a red car.

  12. Semantic Web (2) UsedCars Website User Mapping Service BCN Cars • Ontologies: • Define relationships: relationship between, say, a postcode, a town, a suburb, etc Wordnet Ford New Cars

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