Industrialised, Integrated, Intelligent sustainable Construction - I3con

SUSTAINABLE CONSTRUCTION HANDBOOK 2
Digest authentication [17], which ensures that client passwords are not sent in clear text. It should be
noted that Spring Security does not provide transport-layer security, however it can be used in
conjunction with an appropriate transport layer security mechanism (e.g. HTTPS) to provide a secure
data channel in addition to authentication and authorisation. The Spring Security authorisation
mechanism can be used to control access to class methods, object instances, and HTTP resources
(identified via a URL pattern).
Two client roles have been defined for the I3CON REST API. Clients who are granted the role
ROLE_WSN_QUERY are permitted to query WSN data. Clients who are granted the role
ROLE_WSN_TASK are allowed to perform tasking operations on the WSN network. Clients who are
granted both roles are allowed to perform WSN query and tasking operations. Spring Security can be
configured to obtain client details from a variety of sources, for example an in-memory map, or a
relational database. The access control mechanism required for the I3CON prototype is relatively
simple, and is expected to support a small number of clients. For this reason the client details (i.e.
username, password, and assigned roles) are stored in an in-memory map that is configured during
application start-up from an XML configuration file. This provides the flexibility necessary to
configure and change users after the system has been deployed.
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WSN Health Monitoring Application
Related work
A number of related works are briefly discussed below. MOTE-VIEW is a client-tier application
developed by Crossbow designed to perform as a sensor network monitoring and management tool
[8]. NanoMon [9] is software developed for WSN monitoring which is also capable of visualising the
history of received sensed data as well as network topology. In [10] a middleware service is proposed
for monitoring of sensor networks by using sensor agent nodes equipped with error/failure
information forwarding capability. An execution and monitoring framework for sensor network
services and applications, called ISEE is proposed in [11]. One of the ISEE modules provides a
consistent graphical representation of any sensor network. A work on using heterogeneous
collaborative groupware to monitor WSNs is presented in [12]. Our work focuses on providing
network health monitoring services that complies and utilises the REST-based web services SOA
style.
Design and Configuration of WSN Health Monitoring Application
The Health Monitoring application uses data that is stored in the data base and provided by the Virtual
Gateway to identify several types of possible operational problems in the WSN, as listed below:
• The battery level of a mote is below a configurable threshold.
• The time-stamp of the most recent measurement from a sensor is older than a configurable
number of milliseconds.
• No measurements have been received from a sensor.
The Health Monitoring application is implemented as a Java web application that runs inside a
standard servlet container, e.g. Apache Tomcat. The application can be configured to automatically
analyse the health of the WSN at regular intervals, and it is also possible to manually initiate a check
of the WSN through the user interface. The application is configured via a properties file located at
i3con-manager/WEB-INF/application.properties. The configurable properties are shown below:
• bimResource – the location of the XML resource that describes the topology and structure of
the deployed WSN, e.g. file:i3con_margaritas_deployment_01.xml. This file is the same format
as used by the virtual gateway. The structure of deployed WSN is shown in Figure 1.
• moteLowBatteryWarningLevel – the battery level in volts below which a mote battery is
considered too low.
• sensorMeasurementTooOldWarningInterval – the age in milliseconds above which the most
recent measurement from a sensor is considered too old.