jade.content.onto
Class Ontology

java.lang.Object
  |
  +--jade.content.onto.Ontology
Direct Known Subclasses:
ACLOntology, BasicOntology, DFAppletOntology, ExceptionOntology, FIPAManagementOntology, IntrospectionOntology, JADEManagementOntology, MobilityOntology

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:

Application-specific ontologies are implemented through objects of class Ontology.
An ontology is characterized by: 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: The framework already provides two ontologies that you can use for building your application-specific ontologies: Application-specific ontologies should be implemented extending one of them

Author:
Federico Bergenti - Universita` di Parma, Giovanni Caire - TILAB
See Also:
Concept, AbsConcept, ConceptSchema, ACLOntology, BasicOntology, Serialized Form

Constructor Summary
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
 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.
 AbsObject fromObject(java.lang.Object obj)
          Converts a Java object into a proper abstract descriptor.
protected  AbsObject fromObject(java.lang.Object obj, Ontology globalOnto)
          Converts a Java object into a proper abstract descriptor.
 java.lang.Class getClassForElement(java.lang.String name)
          Retrieves the concrete class associated with name in the vocabulary.
 java.lang.String getName()
          Retrieves the name of this ontology.
 ObjectSchema getSchema(java.lang.String name)
          Retrieves the schema associated with name.
 java.lang.Object toObject(AbsObject abs)
          Converts an abstract descriptor to a Java object of the proper class.
protected  java.lang.Object toObject(AbsObject abs, java.lang.String lcType, Ontology globalOnto)
          Converts an abstract descriptor to a Java object of the proper class.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, 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.

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 associated with name. 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 -  

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 name in the vocabulary. 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

toObject

protected java.lang.Object toObject(AbsObject abs,
                                    java.lang.String lcType,
                                    Ontology globalOnto)
                             throws jade.content.onto.UnknownSchemaException,
                                    UngroundedException,
                                    OntologyException
Converts an abstract descriptor to a Java object of the proper class.
Parameters:
abs - the abstract descriptor.
lcType - the type of the abstract descriptor to be translated aconverted into lower case. This is passed as parameters to avoid making the conversion to lower case for each base ontology.
globalOnto - The ontology this ontology is part of (i.e. the ontology that extends this ontology).
Returns:
the object
Throws:
jade.content.onto.UnknownSchemaException - If no schema for the abs descriptor to be translated is defined in this ontology.
UngroundedException - if the abstract descriptor contains a variable
OntologyException - if some mismatch with the schema is found * ontology. In this case UnknownSchema

fromObject

protected AbsObject fromObject(java.lang.Object obj,
                               Ontology globalOnto)
                        throws jade.content.onto.UnknownSchemaException,
                               OntologyException
Converts a Java object into a proper abstract descriptor.
Parameters:
obj - the object
globalOnto - The ontology this ontology is part of (i.e. the ontology that extends this ontology).
Returns:
the abstract descriptor.
Throws:
jade.content.onto.UnknownSchemaException - If no schema for the object to be translated is defined in this ontology.
OntologyException - if some mismatch with the schema is found

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