Mobile Agents in Healthcare, a Distributed Intelligence Approach - Computational Intelligence in Healthcare: Advanced Methodologies - page 47

Algorithm 1 : Strong mobility.
begin
Task A
doMove () ;
Task B

Algorithm 2 : Weak mobility.
begin
switch state do
case 0
Task A;
state = 1;
doMove () ;
break;
case 1
Task B;
break;

end

end

end

Fig. 1. Equivalent algorithms using strong and weak mobility.

of mobility is highly dependent with the underlying computer architectures or virtual
machines, which hinders the achievement of interoperable systems.
Weak mobility does not capture the execution state, as a consequence the code is
always resumed from the first line of code. This is not a major issue, since part of
the agent execution state can be saved as agent data. An example, see Algorithm 2
of Figure 1, is the use of switch control flow statements driven by a simple variable
which is updated and saved in each agent execution. Therefore, the execution can be
approximately resumed in a specific block of code. This migration type is more difficult
to manage by the agent developer, but it is the most flexible and portable alternative.

2.3.2 Agent Itineraries
Agent itineraries are the lists of locations that mobile agents visit during their life. The
concept of itinerary was firstly introduced in the Concordia [52] agent middleware. The
concept is specially important when security is introduced to mobile agents.
Two basic types of itineraries can be distinguished. On the one hand, there are static
itineraries , which are decided when the agent is created. They comprise the set of or-
dered locations that the agent will visit during its life. And, on the other hand, there are
dynamic itineraries , which are not initially preestablished and are decided during the
agent life according to its necessities.

2.4 Advantages

Although there is no application that cannot be conceived without the existence of mo-
bile agents, they ease the implementation of applications which require:

- Task delegation: Due to the inherent autonomy of agents and mobile agents, they
can be assigned with a set of tasks which the agent performs on behalf of its owner,
e.g., in Section 3 is described a medical application where the task of searching for
patients information is delegated to an specific agent.
- Asynchronous processing: Mobile agent execution is not dependent on a contin-
uous communication with the agent owner or the home agent platform. Therefore,