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KNOWLEDGE REPRESENTATION
Ontologies
Communication – Network Management Technologies
Rashid Mijumbi
Barcelona, April 2011
Data and Information ModelsDefinition
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
DM 1 DM 3
IM 1
DM 2
Conceptual/Abstract
model for designers and
operators – High Level
Representation
Concrete model (for
implementors) – Low
Level Representation –
More Details
Data Models (1)The “Necessary Evil”
IPsec VPN MPLS VPN MPLS – TE MPLS – QoS
Specific Device Model
Specific Device Model
Specific Device Model
Specific Device Model
Specific Device #1
Specific Device #2
Specific Device #3
Specific Device #4
Tra
nsla
tion
La
yer
N Different Technologies
Atleast N*M translations
needed
M Devices
Heterogeneity in systems makes different Data Models a necessity
Data Models (2)Problems
Data harmonisation problem in Data Models
Billing ApplicationCustomer Name: rashid.mijumbi
Fault Management Application
Customer Name: mrashid
Security ApplicationCustomer Name: rmijumbi
Information Models (1)Abstraction, Data Harmonised (no Conflicts)
Information Model
Standards – Based Data Model
Vendor – Based Data Model
1 : N
1 : M
Information Models (2)Router Configuration Example
CISCO
Juniper
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
routing-instances { routing-instance-name {
protocols { bgp {
group group-name; { peer-as as-number;
neighbor ip-address; } } } } }
- Different Languages
- Different Semantics
- Different programming models
DEFINING BGP PEERS
Ontologies (1)
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
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.
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.
Semantic Web (1)
User lives in Barcelona and
wants to buy a car locally. He
can afford up to £500. He
wants a red car.
<car><location>Hospitalet</location><price>€400</price><colour>maroon</colour><description>Old banger</description><model>Ford Escort</model>
</car>
UsedCars WebsiteUser
A new form of web content that is meaningful to computers - Berners-Lee 2001
This is because computers cannot process
the semantics that are associated with
web content
Semantic Web (2)
Ontologies:• Define relationships:
relationship between, say, a postcode, a town, a suburb, etc
Mapping Service
User
Wordnet
Ford New Cars
BCN Cars
UsedCars Website