Ontologies

1. OntologiesOntologies
Antonio Villavicencio
COMMUNICATIONS NETWORKS MANAGEMENT
TECHNOLOGIES
Session 4

2. OutlineOutline
Sharing Knowledge
Network Management Models
What is the purpose of an ontology?
What is an ontology in Network
Management?
Applying ontologies to Network
managment integration

3. Sharing KnowledgeSharing Knowledge
 Knowledge sharing is the transfer of knowledge
from one person to another, or from any group
to any other group or from one person to any
group or from any group to one person
 When the sender and the recipient can be
arbitrary entities that might not, and in most
cases do not, use the same language or the
same terminology, extra care must be taken in
the messages that are sent from one party to the
other.

4. Sharing KnowledgeSharing Knowledge
A message, with a sender and a receiver, which
contains structure data, is information.
The information must be structured in such a
way that the receiver is able to understand the
information, and indeed able to gain knowledge
from the information, even though the receiver is
using a different language and a different
terminology.

5. Network Management ModelsNetwork Management Models
Critical Problem“How are data analysed and
turned into knowledge, so that this knowledge
may be shared and reused?”
 There is a multiplicity of network management
models, which use different technologies for
resource management, such as WBEM (Web
Based Entreprised Management) or DMI
(Desktop Management Interface).
 Every model need a language to define the
resources to be managed and ensure the
comunication among these resources.

6. Different Languages for differentDifferent Languages for different
integrated modelsintegrated models
 Each integrated model has its own management
information language:
oSMI (Structure of Management Information) for
SNMP
oGDMO (Guidelines for the Definition of
Managed Objects) for CMIP
oMIF (Management Information Format) for DMI
oCIM (Common Information Model) for WBEM

7. Integrated view of the wholeIntegrated view of the whole
management systemmanagement system
 When different technologies coexist in the same
managed system interoperability among all the
devices is mandatory to provide a integrated
view of the whole managed system.
 A resource can be described with two different
management languages, in this case a
translation it is applied between the defined
structures of their descriptions, but not between
their meenings

8. What is the purpose of anWhat is the purpose of an
ontology?ontology?
 An ontology is a network mangament tool to
integrate heterogenous definitions in order to
achive semantic interoperability of different
management models and languages
Shared ontologies ensure that different devices
and applications communicate about different
aspects of the same entity in a standard way

9. What is the purpose of anWhat is the purpose of an
ontology?ontology?
 “An ontology is the definition of a set of
concepts, its taxonomy and the rules that
govern such concepts”
 Ontology describes a domain, while a knowledge
base (based on an ontology) describes particular
state of affairs. Each knowledge based system
or agent has its own knowledge base, and only
what can be expressed using an ontology can be
stored and used in the knowledge base. When
an agent wants to communicate to another
agent, it uses the constructs from some
ontology. In order to understand in
communication, ontologies must be shared
between agents.

10. The Ontological CommitmentsThe Ontological Commitments
The ontological commitments are agreements to
use a particular vocabulary in a consistent way.
This means that users of the ontology do not
have to share a common knowledge base;
rather, each user is free to know and reason
independently as long as when it asks for
information contained in the ontology, those
actions are consistent. Hence, a commitment to a
common ontology is a guarantee of consistency,
but not completeness, with respect to queries
and assertions using the vocabulary defined in
the ontology.

11. What is an ontology in NetworkWhat is an ontology in Network
Management?Management?
 An ontology is a network managament tool to
integrate heterogenous definition to achive
semantic interoperability of different
management models and languages
 In a basic concept, an ontology defines the terms
used to define and represent a particular domain

12. Applying ontologies to NetworkApplying ontologies to Network
managment integrationmanagment integration
For example, with CIM, semantic
interoperability is not completely achieved;
therefore it should be extended
A method to extend the interoperability
would be to create a network management
model based on ontologies

13. Applying ontologies to NetworkApplying ontologies to Network
managment integrationmanagment integration
This can be achieved by merging every
model with CIM, including all necessary
mapping rules.
A set of steps can be defined
Translate all management information
models to work with a single representation
language
Merge the models in a global ontology,
defining at the same time mapping rules
between the global ontology and each model
Add a set of formulas or axioms to the
ontology to make it heavyweight

14. Structure of a Mapping ontologyStructure of a Mapping ontology

15. Structure of a Mapping ontologyStructure of a Mapping ontology
The structure of a very simple mapping
ontology is depicted in the figure: Each
possible element of the ontology (concepts,
attributtes, relations) has a translation
formula.
Other attributes can be added to that
element, such a reference to its definition.
At the same time, each formula has a set of
the source and target that can take part on
it, and a set of expression used to translate
from the set of source elements to the set of
target element.

16. Translating elementsTranslating elements
A manager based on both, the global ontology
and the mapping ontology would work, for
example in the following way . If it needs to
obtain all the instances of a certain element of
the global ontology, it would search in the
mapping ontology, finding also related formula
and the corresponding elements of the merged
models.
The expression contained in the formula would
then be applied to translate elements of the
merged models to fit in the global ontology, and
the desired instances would be obtained

17. ReferencesReferences
[1] Jorge E. López de Vergara and Others,
Ontologies: Giving Semantics to Network
Management Models
http://citeseerx.ist.psu.ed
[2]
http://www.obitko.com/tutorials/ontologie
s-semantic-web/expressing-ontology.html
[3] Jos de Bruijn,
http://www.deri.org/fileadmin/documents
/DERI-TR-2003-10-29.pdf