Package jade.content.onto

Class Ontology

  • All Implemented Interfaces:
    Serializable, Serializable
    Direct Known Subclasses:
    BasicOntology, BeanOntology, BehaviourLoadingOntology, DFAppletOntology, ExceptionOntology, FIPAManagementOntology, IntrospectionOntology, JADEManagementOntology, JavaCollectionOntology, LogManagementOntology, MobilityOntology, PersistenceOntology, SerializableOntology, SLOntology
    public class Ontology
extends 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 Detail

      • Ontology

        public Ontology​(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​(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​(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​(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 String getName()
        Retrieves the name of this ontology.
        Returns:
        the name of this ontology.

      • getSchema

        public ObjectSchema getSchema​(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​(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

      • getClassForElement

        public Class getClassForElement​(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

      • toObject

        protected Object toObject​(AbsObject abs,
                          String lcType,
                          Ontology globalOnto)
                   throws 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:
        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​(Object obj,
                               Ontology globalOnto)
                        throws 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:
        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​(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

      • getOwnConceptNames

        public 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 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 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 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 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 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​(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()

      • isBaseOntology

        public static boolean isBaseOntology​(Ontology[] oo,
                                     String name)

      • dump

        public void dump()
        Dump ontology to default output stream

      • dump

        public void dump​(PrintStream ps)
        Dump ontology to specified PrintStream