jade.content.onto

Class Ontology

java.lang.Object

jade.content.onto.Ontology

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

BasicOntology, BeanOntology, BehaviourLoadingOntology, ExceptionOntology, FIPAManagementOntology, IntrospectionOntology, JADEManagementOntology, JavaCollectionOntology, MobilityOntology, SerializableOntology, SLOntology

public class Ontology
extends java.lang.Object
implements Serializable

An application-specific ontology describes the elements that agents can use within content of messages. It defines a vocabulary and relationships between the elements in such a vocabulary. The relationships can be:

• structural, e.g., the predicate fatherOf accepts two parameters, a father and a set of children;
• semantic, e.g., a concept of class Man is also of class Person.

Application-specific ontologies are implemented through objects of class Ontology.
An ontology is characterized by:

• one name;
• one (or more) base ontology that it extends;
• a set of element schemas.

Element schemas are objects describing the structure of concepts, actions, and predicates that are allowed in messages. For example, People ontology contains an element schema called Person. This schema states that a Person is characterized by a name and by an address: ConceptSchema personSchema = new ConceptSchema(PERSON); personSchema.addSlot(NAME, stringSchema); personSchema.addSlot(ADDRESS, addressSchema, ObjectSchema.OPTIONAL); where PERSON, NAME and ADDRESS are string constants. When you register your schema with the ontology, such constants become part of the vocabulary of the ontology.
Schemas that describe concepts support inheritance. You can define the concept Man as a refinement of the concept Person: ConceptSchema manSchema = new ConceptSchema(MAN); manSchema.addSuperSchema(personSchema); Each element schema can be associated with a Java class to map elements of the ontology that comply with a schema with Java objects of that class. The following is a class that might be associated with the Person schema: public class Person extends Concept { private String name = null; private Address address = null; public void setName(String name) { this.name = name; } public void setAddress(Address address) { this.address = address; } public String getName() { return name; } public Address getAddress() { return address; } } When sending/receiving messages you can represent your content in terms of objects belonging to classes that the ontology associates with schemas.
As the previous example suggests, you cannot use objects of class Person when asking for the value of some attribute, e.g., when asking for the value of address. Basically, the problem is that you cannot 'assign' a variable to an attribute of an object, i.e. you cannot write something like: person.setName(new Variable("X")).
In order to solve this problem, you can describe your content in terms of abstract descriptors. An abstract descriptor is an object that reifies an element of the ontology. The following is the creation of an abstract descriptor for a concept of type Man: AbsConcept absMan = new AbsConcept(MAN); absMan.setSlot(NAME, "John"); absMan.setSlot(ADDRESS, absAddress); where absAddress is the abstract descriptor for John's address: AbsConcept absAddress = new AbsConcept(ADDRESS); absAddress.setSlot(CITY, "London"); Objects of class Ontology allows you to:

• register schemas with associated (i) a mandatory term of the vocabulary e.g. NAME and (ii) an optional Java class, e.g. Person;
• retrieve the registered information through various keys.

The framework already provides the BasicOntology ontology that provides all basic elements, i.e. primitive data types, aggregate types, etc. Application-specific ontologies should be implemented extending it.

Author:

Federico Bergenti - Universita` di Parma, Giovanni Caire - TILAB

See Also:

Concept, AbsConcept, ConceptSchema, BasicOntology, Serialized Form

Constructor Summary

Constructors

Constructor and Description
Ontology(java.lang.String name, Introspector introspector) Construct an Ontology object with a given name that uses a given Introspector to convert between Java objects and abstract descriptors.
Ontology(java.lang.String name, Ontology base) Construct an Ontology object with a given name that extends a given ontology.
Ontology(java.lang.String name, Ontology[] base, Introspector introspector) Construct an Ontology object with a given name that extends a given set of ontologies and that uses a given Introspector to convert between Java objects and abstract descriptors.
Ontology(java.lang.String name, Ontology base, Introspector introspector) Construct an Ontology object with a given name that extends a given ontology and that uses a given Introspector to convert between Java objects and abstract descriptors.

Method Summary

Modifier and Type	Method and Description
void	add(ObjectSchema schema) Adds a schema to this ontology
void	add(ObjectSchema schema, java.lang.Class javaClass) Adds a schema to the ontology and associates it to the class javaClass
static void	checkIsTerm(java.lang.Object obj) Check whether a given object is a valid term.
ConceptSlotFunction	createConceptSlotFunction(java.lang.String slotName, Concept c) Create a ConceptSlotFunction for a given slot of a given Concept.
void	dump() Dump ontology to default output stream
void	dump(java.io.PrintStream ps) Dump ontology to specified PrintStream
static AbsObject	externalizeSlotValue(java.lang.Object obj, Introspector introspector, Ontology referenceOnto)
AbsObject	fromObject(java.lang.Object obj) Converts a Java object into a proper abstract descriptor.
java.util.List	getActionNames() Retrieve the names of all agent actions defined in this ontology (including extended ontologies).
java.lang.Class	getClassForElement(java.lang.String name) Retrieves the concrete class associated with element name in this ontology.
java.util.List	getConceptNames() Retrieve the names of all concepts defined in this ontology (including extended ontologies).
Introspector	getIntrospector()
java.lang.String	getName() Retrieves the name of this ontology.
java.util.List	getOwnActionNames() Retrieve the names of the agent actions defined in this ontology only (excluding extended ontologies).
java.util.List	getOwnConceptNames() Retrieve the names of the concepts defined in this ontology only (excluding extended ontologies).
java.util.List	getOwnPredicateNames() Retrieve the names of the predicates defined in this ontology only (excluding extended ontologies).
java.util.List	getPredicateNames() Retrieve the names of all predicatess defined in this ontology (including extended ontologies).
static java.util.List<ObjectSchema>	getReferencedSchemas(ObjectSchema rootSchema)
ObjectSchema	getSchema(java.lang.Class clazz) Retrieves the schema associated to a given class in this ontology.
ObjectSchema	getSchema(java.lang.String name) Retrieves the schema of element name in this ontology.
static java.lang.Object	internalizeSlotValue(AbsObject abs, Introspector introspector, Ontology referenceOnto)
static boolean	isBaseOntology(Ontology[] oo, java.lang.String name)
java.lang.Object	toObject(AbsObject abs) Converts an abstract descriptor to a Java object of the proper class.
java.lang.String	toString()
protected void	useConceptSlotsAsFunctions() Instruct this ontology to support usage of concept slots as functions.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Ontology

public Ontology(java.lang.String name,
                Ontology base)

Construct an Ontology object with a given name that extends a given ontology. The ReflectiveIntrospector is used by default to convert between Java objects and abstract descriptors.

Parameters:

name - The identifier of the ontology.

base - The base ontology.

Ontology

public Ontology(java.lang.String name,
                Introspector introspector)

Construct an Ontology object with a given name that uses a given Introspector to convert between Java objects and abstract descriptors.

Parameters:

name - The identifier of the ontology.

introspector - The introspector.

Ontology

public Ontology(java.lang.String name,
                Ontology base,
                Introspector introspector)

Construct an Ontology object with a given name that extends a given ontology and that uses a given Introspector to convert between Java objects and abstract descriptors.

Parameters:

name - The identifier of the ontology.

base - The base ontology.

introspector - The introspector.

Ontology

public Ontology(java.lang.String name,
                Ontology[] base,
                Introspector introspector)

Construct an Ontology object with a given name that extends a given set of ontologies and that uses a given Introspector to convert between Java objects and abstract descriptors.

Parameters:

name - The identifier of the ontology.

base - The base ontology.

introspector - The introspector.

Method Detail

getName

public java.lang.String getName()

Retrieves the name of this ontology.

Returns:

the name of this ontology.

getIntrospector

public Introspector getIntrospector()

add

public void add(ObjectSchema schema)
         throws OntologyException

Adds a schema to this ontology

Parameters:

schema - The schema to add

Throws:

OntologyException

add

public void add(ObjectSchema schema,
                java.lang.Class javaClass)
         throws OntologyException

Adds a schema to the ontology and associates it to the class javaClass

Parameters:

schema - the schema.

javaClass - the concrete class.

Throws:

OntologyException

getSchema

public ObjectSchema getSchema(java.lang.String name)
                       throws OntologyException

Retrieves the schema of element name in this ontology. The search is extended to the base ontologies if the schema is not found.

Parameters:

name - the name of the schema in the vocabulary.

Returns:

the schema or null if the schema is not found.

Throws:

OntologyException

getSchema

public ObjectSchema getSchema(java.lang.Class clazz)
                       throws OntologyException

Retrieves the schema associated to a given class in this ontology. The search is extended to the base ontologies if the schema is not found.

Parameters:

clazz - the class whose associated schema must be retrieved.

Returns:

the schema associated to the given class or null if the schema is not found.

Throws:

OntologyException

toObject

public java.lang.Object toObject(AbsObject abs)
                          throws OntologyException,
                                 UngroundedException

Converts an abstract descriptor to a Java object of the proper class.

Parameters:

abs - the abstract descriptor.

Returns:

the object

Throws:

UngroundedException - if the abstract descriptor contains a variable

OntologyException - if some mismatch with the schema is found

See Also:

fromObject(Object)

fromObject

public AbsObject fromObject(java.lang.Object obj)
                     throws OntologyException

Converts a Java object into a proper abstract descriptor.

Parameters:

obj - the object

Returns:

the abstract descriptor.

Throws:

OntologyException - if some mismatch with the schema is found

See Also:

toObject(AbsObject)

getClassForElement

public java.lang.Class getClassForElement(java.lang.String name)
                                   throws OntologyException

Retrieves the concrete class associated with element name in this ontology. The search is extended to the base ontologies

Parameters:

name - the name of the schema.

Returns:

the Java class or null if no schema called name is found or if no class is associated to that schema.

Throws:

OntologyException - if name is null

checkIsTerm

public static void checkIsTerm(java.lang.Object obj)
                        throws OntologyException

Check whether a given object is a valid term. If it is an Aggregate (i.e. a List) it also check the elements.

Throws:

OntologyException - if the given object is not a valid term

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getOwnConceptNames

public java.util.List getOwnConceptNames()

Retrieve the names of the concepts defined in this ontology only (excluding extended ontologies). It should be noticed that an agent-action is itself a concept and therefore the returned list also includes names of agent-actions defined in this ontology.
NOT available in J2ME

Returns:

the names of the concepts defined in this ontology only (excluding extended ontologies)

getConceptNames

public java.util.List getConceptNames()

Retrieve the names of all concepts defined in this ontology (including extended ontologies). It should be noticed that an agent-action is itself a concept and therefore the returned list also includes names of agent-actions defined in this ontology.
NOT available in J2ME

Returns:

the names of all concepts defined in this ontology (including extended ontologies)

getOwnActionNames

public java.util.List getOwnActionNames()

Retrieve the names of the agent actions defined in this ontology only (excluding extended ontologies).
NOT available in J2ME

Returns:

the names of the agent actions defined in this ontology only (excluding extended ontologies)

getActionNames

public java.util.List getActionNames()

Retrieve the names of all agent actions defined in this ontology (including extended ontologies).
NOT available in J2ME

Returns:

the names of all agent actions defined in this ontology (including extended ontologies)

getOwnPredicateNames

public java.util.List getOwnPredicateNames()

Retrieve the names of the predicates defined in this ontology only (excluding extended ontologies).
NOT available in J2ME

Returns:

the names of the predicates defined in this ontology only (excluding extended ontologies)

getPredicateNames

public java.util.List getPredicateNames()

Retrieve the names of all predicatess defined in this ontology (including extended ontologies).
NOT available in J2ME

Returns:

the names of all predicatess defined in this ontology (including extended ontologies)

createConceptSlotFunction

public ConceptSlotFunction createConceptSlotFunction(java.lang.String slotName,
                                                     Concept c)
                                              throws OntologyException

Create a ConceptSlotFunction for a given slot of a given Concept. The ConceptSlotFunction class allows treating the slots of an ontological concept as functions. For instance, if an ontology defines a concept Person with a slot name and a slot age, it is possible to create expression such as
(= (age (Person :name John)) 41)
(> (age (Person :name John)) (age (Person :name Bill)))
(iota ?x (= (age (Person :name John)) ?x))
NOT available in MIDP

Parameters:

slotName - The name of the slot

c - The concept a ConceptSlotFunction must be created for. This concept must have a slot called slotName

Returns:

A ConceptSlotFunction for the given slotName of the given Concept

Throws:

OntologyException

Since:

JADE 3.7

See Also:

ConceptSlotFunction, useConceptSlotsAsFunctions()

useConceptSlotsAsFunctions

protected void useConceptSlotsAsFunctions()

Instruct this ontology to support usage of concept slots as functions. This method must be invoked after all schemas have been completely defined and added to this ontology.

Since:

JADE 3.7

See Also:

ConceptSlotFunction, createConceptSlotFunction(String, Concept)

externalizeSlotValue

public static AbsObject externalizeSlotValue(java.lang.Object obj,
                                             Introspector introspector,
                                             Ontology referenceOnto)
                                      throws OntologyException

Throws:

OntologyException

internalizeSlotValue

public static java.lang.Object internalizeSlotValue(AbsObject abs,
                                                    Introspector introspector,
                                                    Ontology referenceOnto)
                                             throws OntologyException

Throws:

OntologyException

getReferencedSchemas

public static java.util.List<ObjectSchema> getReferencedSchemas(ObjectSchema rootSchema)
                                                         throws OntologyException

Throws:

OntologyException

isBaseOntology

public static boolean isBaseOntology(Ontology[] oo,
                                     java.lang.String name)

dump

public void dump()

Dump ontology to default output stream

dump

public void dump(java.io.PrintStream ps)

Dump ontology to specified PrintStream