The findings stemming from the analysis of the
results was useful for the formulation of the following
answers to the research questions set in this research:
RQA1: The direct data streaming from the fog layer
to the monitoring layer without crossing the Cloud
has significantly reduced the system latency
compared to the Cloud-only approach. This
perspective is evident across various configurations,
showcasing the system's adaptability for real-time
visualization.
RQA2: With minimal computing capacities on a
macOS laptop and being accommodated with the
whole OTel evaluation structure, the proposed
framework showed stable performance in latency,
processing, and resource utilization across the
configurations 1, 2, 3 and 4. Thus, a capacity for
workload scalability. The minor limitations noticed in
the configuration 5 highlighted the experimental
setup constraint caused by using a single machine for
the whole system deployment. Furthermore, the
scalability and efficiency of the system can be further
enhanced in a distributed deployment in real-world
conditions. Previous approaches did not address
performance measurement using OpenTelemetry.
The framework developed in this research showed
lower latency despite the increase in streams. This
was confirmed by the significant difference in the
obtained latency compared to the results recorded by
(Asghar et al., 2021b) for analogous configurations:
452 ms and 1082 ms vs 9.94 ms and 16.5 ms.
It is also worth of mentioning that the proposed
framework was evaluated by conducting an
experiment design including a System Usability Scale
(SUS). The experiment provided qualitative and
quantitative data from a group of rehabilitation
experts and showed a good usability of the proposed
visual analytics framework. However, the details of
this study can be included in this paper due to the
limitation of space.
7 CONCLUSIONS
The main objective of this paper is to evaluate the
performance of visual analytics RPM framework
dedicated to neuromotor rehabilitation of stroke
survivors. The proposed framework is based on fog-
computing with new approach of splitting the data
stream into real-time and batch. The real-time stream
skips the Cloud layer and flows directly to the
monitoring layer, where the therapist interface for
data visualization was included. This approach was
evaluated in terms of latency and scalability.
Common evaluation techniques of fog-based systems
use simulation tools such as iFogSim. However, in
this paper the evaluation was performed using
observability and instrumentation through OTel. This
unified opensource framework helps in generating,
collecting, and transmitting telemetry data. Five
configurations were used by escalating the workload
for the evaluation of the proposed framework and for
obtaining deep insight into the behaviour of its
different components. The defined KPis for
evaluation were End-to-End latency, throughput,
processing time and resource utilization. The findings
suggested that the latency of the proposed system was
significantly low when compared to cloud-only
implementation. The scalability of the system was
reflected by its capacity of handling the increased
workload across different configuration scenarios.
Nevertheless, the minor limitations noticed in the
fifth configuration highlighted the experimental
setup's constraints imposed by using a single machine
for the whole system deployment. In future work, the
scalability and efficiency of the system will be further
enhanced by the implementation of a distributed
deployment in real-world conditions.
ACKNOWLEDGEMENTS
The authors acknowledge the contribution of the
French Ministry of Foreign Affairs and Campus
France in Morocco for their financial support to
conduct the research presented in this paper.
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