Embedded Rule-based Management for Content-based DTNs - Advances in Network-Embedded Management and Applications - page 99

are congured to emit a notication every 5s. The increment on the memory load
produced by the activation of the watchers can be seen at the beginning of the
graphs in Figure 5(b) . After the watchers have being submitted, the client start
producing a dierent subscription every 10s. Every subscription matches with all
the notications emitted by the sensor. In order to simulate the load of the PDP re-
conguring the routing protocol, every time a subscription is received at the sensor,
the PDP recongures RON's buer-size to the same value of 40 messages.
Is worth noticing the evolution of the percentage of CPU consumed by the
system in Figure 5(a) and its the memory load in Figure 5(b) . The CPU consumed
by Rmoon and the PDP combined is never beyond 10%. The CPU consumed by
the notications bus is quite spiky but with maximums of around 50%. This leaves
plenty of CPU resources for other tasks. Regarding memory load, it grows during
the arriving of the watchers up to about 1.2MB and then grows moderately as
more subscriptions arrive. Considering that more than 30 dierent subscriptions
matching the data of ten dierent watchers every 5s is an extremely high load for a
environmental sensor, we conclude that the tested hardware can cope comfortably
with the expected loads.
7 Conclusions and Future Work
In this paper we have presented the self-management part of an opportunistic net-
work of in-house environmental sensors and a myriad of mobile devices that act
as the carriers of the collected data. Our work shows that a content-based, op-
portunistic routing protocol benets from some self-conguration features, such as
the dynamic adaptation of the buer-size of a node to the density of the network.
We conclude that it is feasible to deploy rule-based self-management capabilities
inside very-constrained devices such as the prototype sensor presented in Section 5.
The footprint of the management components is not negligible but, from the initial
experiments, we observe that it is small enough to keep us working on this path.
The system presented in this paper is in its developing stage, therefore much
work remains to be made. The routing protocol presented has many aspects to be
improved, but regarding the self-management functionality of the system, besides
its feasibility, its correctness must be tested extensively. A whole set of management
rules and scenarios are being experimented on the ns3 simulator.
Finally, despite the fact that DEMOS project takes advantage of the Uruguayan
and Brazilian particularities, and proposes to use the platform of low-cost laptops of
the OLPC program, the project idea is easily translatable to other communication
platforms that are becoming ubiquitous in developing countries such as cellular
phones with Bluetooth or other wireless capabilities.
Acknowledgments
This work was partially funded by the Research Funding Initiatives of the Latin
American and Caribbean Collaborative ICT Research (LACCIR) virtual institute.