Summary
Background: E-homecare creates opportunities to provide care faster, at lower cost and higher
levels of convenience for patients. As e-homecare services are time-critical, stringent
requirements are imposed in terms of total response time and reliability, this way
requiring a characterization of their network load and usage behavior. However, it
is usually hard to build testbeds on a realistic scale in order to evaluate large-scale
e-home-care applications.
Objective: This paper describes the design and evaluation of the Network Simulator for Web Services
(WS-NS), an NS2-based simulator capable of accurately modeling service-oriented architectures
that can be used to evaluate the performance of e-homecare architectures.
Methods: WS-NS is applied to the Coplintho e-homecare use case, based on the results of the
field trial prototype which targeted diabetes and multiple sclerosis patients. Network-unaware
and network-aware service selection algorithms are presented and their performance
is tested.
Results: The results show that when selecting a service to execute the request, suboptimal
decisions can be made when selection is solely based on the service’s properties and
status. Taking into account the network links interconnecting the services leads to
better selection strategies. Based on the results, the e-homecare broker design is
optimized from a centralized design to a hierarchical region-based design, resulting
in an important decrease of average response times.
Conclusions: The WS-NS simulator can be used to analyze the load and response times of large-scale
e-homecare architectures. An optimization of the e-homecare architecture of the Coplintho
project resulted in optimized network overhead and more than 45% lower response times.
Keywords
Home care services - simulation - performance - optimization - medical informatics
