International Journal of Distributed Sensor Networks
and network of such systems and is also an important
link to achieving a high-speed information platform for
coal mines. Currently, the common communication modes
that can be operated in the coal mine industry include the
modulation and demodulation-based analog transmission
mode, the distributed control system- (DCS-) based RS
serial communication mode, the eldbus control system
(FCS) structure-based intelligent sensor transmission mode,
and the wireless transmission mode. e eldbus technique
has been widely used in the industrial elds of various
industries and can be used in either the master-slave mode
or the multimaster mode as needed. e multimaster mode
allows data exchanges among monitoring devices in dierent
locations to be more exible and direct. Due to its extremely
high reliability and unique design, as well as its transmis-
sion characteristics (high speed, long distance), the eldbus
techniqueisespeciallysuitableforuseintheinterconnection
between eld monitoring devices.
Established by densely distributing a large number of
microsensor nodes capable of communicating and calculat-
ing in the unattended monitor regions, wireless sensor net-
works (WSNs) are intelligent autonomous control network
systems that can self-complete planned tasks according to the
environment. Based on the aforementioned main issues in
the existing coal mine gas monitoring systems, the techno-
logicaladvantagesofWSNscanbeusedtoachieveseamless
underground safety monitoring coverage by combining their
advantages with those of wired networks.
Web ser vices [–] are the services provided via Web
technology. Generally, Web services are based on hypertext
transfer protocol (HTTP). e World Wide Web Consortium
(WC) denes Web services as soware systems marked
by uniform resource identiers (URIs); the common Web
interface is dened and described by extensible markup
language (XML) documents to provide outer calling. During
the calling process, a Web service interacts with another Web
service or other soware systems using XML information
encapsulation via HTTP. e Web is oen used as the
message transfer format between dierent services.
Representational State Transfer (REST) [–]isanet-
work application framework rst proposed by Dr. Roy Field-
ing in his doctoral dissertation. In the REST framework, all
objects and capabilities within a system can be abstracted
as resources, and every resource has a uniform resource
location (URL). For instance, one data entry, one service
operation, one picture, and one video can each be abstracted
asaresource,andeachresourcehasauniqueURLwithin
the system. In the REST framework style, every resource is
exposed to the clients via a unique URL. erefore, clients
can distinguish these interactive objects via their URI. In
addition, clients can also make any request to the resource
based on a certain URI. One major dierence between REST
style Web services and traditional Web services is that REST
does not treat HTTP as the transport layer protocol but the
application layer protocol. Because the URI of a resource is
unique,whenaclientusestheHTTPstandardtooperate
GET, POST, PUT, and DELETE to request the target resource,
the server will understand the HTTP request. GET reads
thedataoftheresource;POSTestablishesanewresource;
PUT updates a resource; and DELETE deletes a resource.
Operating resources via a uniform interface increases the
unity of interaction, reduces the coupling degree between
components, simplies the realization of the client, and
increases the extensibility of the system.
e Web of ings (WoT) [, ] describes the Internet
of things from the aspect of technical implementation. e
WoT uses the design concept and technology of the Web
to abstract the devices in the network environment of the
WoT into resources and service abilities and connects them
to the Web space to establish a heterogeneous network and
distributed terminal-based application environment, which
allows easier access to the embedded devices and services on
theWoT.eWoTusestheWebstandardandexpandsthe
entire ecosystem of the Internet to all types of sensing devices.
In this study, a wireless sensor network was combined
with the controller area network (CAN) bus technology for
the comprehensive and timely monitoring and intelligent
early warning in the underground environment, the pro-
duction data, and the operating state of the equipment. In
addition, based on the WoT technology, all types of param-
eters were collected and transmitted to the remote monitor
center for analysis to provide decision-making information
for clients. If there was a parameter anomaly, the local sensor
nodecouldsetothesoundandlightalarmonsiteand
simultaneously set o the alarm in the remote monitor center
window. e rest of the paper is organized as follows. In
Section , we describe the proposed system architecture.
In Section , we describe dierent scenarios. In Section ,
we present the performance and discussion. Finally, the
conclusions and future work are discussed in Section .
2. Proposed System Architecture
e WoT monitoring platform combines the WSN and the
CAN bus technology to achieve comprehensive and timely
monitoring and early warning of underground environmen-
tal parameters; in addition, the WoT technology is used to
achieve remote monitoring of underground parameters in
the remote monitor center. e entire system makes the
abilities of the various underground sensors available to
the application layer on the access gateway side and the
operational system side via the Web technology; in addition,
the system encapsulates the open interfaces via the REST-
based framework and allows the application layer to access
resources via HTTP. Figure shows the overall architecture
oftheentiresystem.
e service gateway of the WoT is the core node, which
can provide Web services, enabling applications to directly
access the gateway in the Web form to communicate with the
sensors/controllers.
e WoT service server provides WoT services to WoT
applications and also provides such management functions as
identication, routing, and registration for the WoT service
gateway. Hence, applications based on this architecture can
obtain dierent WoT services by accessing the WoT service
gateway and the WoT service platform.