When an agent A communicates with another agent
B, a certain amount of information I is transferred from A to B by means
of an ACL message. Inside the
ACL message, I is represented as a content expression consistent with a
proper content language (e.g. SL) and encoded in a proper format (e.g. string).
Both A and B have their own (possibly different) way of internally representing
I. Taking into account that the way an agent internally represents a
piece information must allow an easy handling of that piece of information, it
is quite clear that the representation used in an ACL content expression is not
suitable for the inside of an agent.
For example the
information that there is a person whose
name is Giovanni and who is 33 years old in an ACL content expression could
be represented as the string
(Person :name
Giovanni :age 33)
Storing this information
inside an agent simply as a string variable is not suitable to handle the
information as e.g. getting the age of Giovanni would require each time to
parse the string.
Considering software
agents written in Java (as rca agents are), information can conveniently be
represented inside an agent as Java objects. For example representing the above
information about Giovanni as an instance (a Java object) of an
application-specific class
class Person {
String name;
int age;
public
String getName() {return name; }
public
void setName(String n) {name = n; }
public
int getAge() {return age; }
public
void setAge(int a) {age =
a; }
….
}
initialized with
name = “Giovanni”;
age = 33;
would allow to handle it very easily.
It is clear however
that, if on the one hand information handling inside an agent is eased, on the
other hand each time agent A sends a piece of information I to agent B,
1)
A needs to convert his
internal representation of I into the corresponding ACL content
expression representation and B needs to perform the opposite conversion.
2)
Moreover B
should also perform a number of semantic checks to verify that I is a
meaningful piece of information, i.e. that it complies with the rules (for
instance that the age of Giovanni is actually an integer value) of the ontology
by means of which both A and B ascribe a proper meaning to I.
The classes included in this package and its sub-packages are designed to automatically perform all the above conversion and check operations, thus allowing developers manipulating information within their agents as Java objects (as described above) without the need of any extra work.