Information Technology Reference
In-Depth Information
The connection of the educational portal and the AV node is made through the middle layer
of the portal architecture, where the electronic services are located. Depending on the
direction of the asked assistance we distinguish reactive and proactive behavior of the
architecture. In the reactive behavior the interaction between the two nodes is initiated by
the portal. This is necessary in the cases when a user request is processed and a service
needs an "expert'' assistance. The service addresses the corresponding agent, located in the
AV. The problem is that, in their nature, the services are passive and static software
modules, intended mainly for the convenient realization and integration of some business
functionality. Therefore they must "transfer'' the responsibility for the activation and
support of the connection to an active component of the architecture, as agents do. To do
this, the service sends a concrete message to the agent's environment, which, on its behalf,
identifies the change of the environment and reacts by interpreting the message. Depending
on the identified need of assistance the agent activates the necessary actions. The reactive
behavior of the architecture could be implemented using a:
Synchronous model - this model is analogous to calling subroutines in programming
languages. In this model the service sends a message to AV and waits for the result
from the corresponding agent before continuing its execution.
Asynchronous model - in the asynchronous model the interaction is accomplished
through some kind of a mechanism for sending and receiving messages.
Fig. 7. Cluster architecture
In the proactive behavior (agents work "on behalf of the user''), an agent from the AV can
determine that in its environment "something is happening'', that would be interesting for
the user, who is assisted by that agent. The agent activates and it can perform certain actions
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