![](bg7.png)
send(…), asend(…), receive(…) and
try_receive(…)
.
ACLMessage msgRx = receive();
if (msgRx != null) {
System.out.println(msgRx);
ACLMessage msgTx = msgRx.createReply();
msgTx.setContent("Hello!");
send(msgTx);
} else {
block();
}
Figure 12: JADE Extract.
The association is a first class concept in modeling
and programming notation (Kristensen, 2006).
Various approaches to notation for non centric
modeling and programming include: Relations
(Rumbaugh, 1987) and associations in OMT
(Rumbaugh, et al., 1991) are object-external
abstractions but only for structural aspects.
Sequence and collaboration diagrams in UML
(Booch, et al., 1998) support the description of
object interaction by means of method invocation.
Association = Activity + Role (Kristensen, 2006)
combines activities (Kristensen & May, 1996) and
roles (Kristensen, 1995) in one abstraction
supporting both roleification and execution. Design
patterns (Gamma, et al., 1994) capture experience
of object oriented design and programming, but are
only mental abstractions. Patterns for object
collaboration include
DECORATOR, OBSERVER, and
MEDIATOR.
6 CONCLUSIONS
In the centric form of message-passing agents the
focus is on the action sequence of the individual
agent and the description of collaboration between
agents is distributed among these. The associative
abstraction is a descriptive unit and supports our
natural understanding of collaboration as shared
between agents. By means of the directive the
description of collaboration becomes simple and
natural.
Challenges for association based on
asynchronous message-passing include
Broadcast messages could be restricted to
associations, i.e. only to agents participating in
the ongoing collaboration.
The facilities supported by an operation similar
to
createReply(…) could improve the
expressional power of associations.
In (JACK 2010) (agent oriented development
environment and agent oriented extensions to
JAVA) a message is received implicitly by the
agent and an associated plan for handling the
message may be initiated: An association could
be seen as a similar plan for several
collaborating agents.
ACKNOWLEDGEMENTS
We thank Palle Nowack at Alexandra Institute for
inspiration and contribution.
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