A WEB-SERVICE BASED APPROACH FOR DEVELOPING

INTEGRABLE NOISE MONITORING MODULES

Nguyen The Cuong, Abdellah Touhafi, Jelmer Tiete and Kris Steenhaut

ETRO, Vrije Universiteit Brussel, Brussel, Belgium

IWT, Erasmushogeschool Brussel, Brussel, Belgium

Keywords: Noise monitoring, Web services, Joomla components, Noise level visualization, Web-based applications,

Sound measurement, Noise pollution.

Abstract: This paper presents a noise monitoring system based on web service technologies. By using microphones

placed in certain locations, the system investigates the level of noise pollution. Sensed data are collected,

processed and visualized. One of the advantages of the system is to provide monitoring modules that can be

added to user websites when necessary. The objective of these modules is to display noise levels at a

specific location in real time. The paper also shows the advantages and capabilities of web services in noise

monitoring systems. Web service interfaces are developed to support database access, by which many users

can query sound database system at the same time. It is believed that the availability of these modules

promotes the participation of urban citizens in the noise monitoring task.

1 INTRODUCTION

Noise pollution is one of the main causes of health

complaints by the inhabitants of urban areas today.

Recent studies concluded that exposure to high

levels of environmental noise can significantly

increase the risk of high blood pressure, heart

failure, hearing disorders and insomnia. Because of

this, noise pollution is recognized as a cause of

decreased productivity and disturbed social behavior

(European Commission Green Paper). The European

Commission recognizes this problem and has made

noise avoidance, reduction and prevention their key

priorities in their current policy. For this purpose, a

directive has been proposed by the European

Commission for all the European Member States to

draw up "strategic noise maps" to assist in

monitoring this environmental problem. These noise

maps should provide a regular overview of detailed

noise levels in agglomerations with more than

250.000 inhabitants (Directive 2002/49/EC). Via a

web-interface, people would have the opportunity to

consult the noise pollution situation in their

neighborhood. We believe that the more users

participate in the noise monitoring tasks, the more

people will understand the issue of noise pollution.

The question is how urban citizens can monitor

noise levels when they are interested in this issue.

In this paper, we describe our approach that

allows citizens to participate in noise monitoring

tasks. The aim of the system is to provide internet

users the capability of monitoring noise pollution.

The work consists of two parts. First, we build a

noise monitoring system enabling to record sound

data level at some given locations. Second, easy-to-

integrate modules are developed based on web

service technology. Web service interfaces are used

for communicating between user applications and

the database system. Because almost all websites are

now powered by Content Management Systems

(CMSs) these modules are built following well-

defined structures that makes them easily integrable

into those systems.

There are different issues discussed in this paper.

Firstly, we analyze the health impact of noise

pollution and the role of web services in monitoring

systems. Secondly, we study the related works on

noise monitoring and web services. Next, we go

through the description of the system and some

components in detail. We then present the

implementations in the system. Finally, we conclude

and present plans for future works with regards to

both noise monitoring and web services.

295

The Cuong N., Touhaﬁ A., Tiete J. and Steenhaut K..

A WEB-SERVICE BASED APPROACH FOR DEVELOPING INTEGRABLE NOISE MONITORING MODULES.

DOI: 10.5220/0003382202950300

In Proceedings of the 1st International Conference on Cloud Computing and Services Science (CLOSER-2011), pages 295-300

ISBN: 978-989-8425-52-2

 2011 SCITEPRESS (Science and Technology Publications, Lda.)

2 THE EFFECT OF NOISE ON

THE PEOPLE HEALTH

Sound is essential in our daily life, but noise is not.

Environmental noise is unwanted sound from

different possible sources, including road and rail

traffic, construction works, aircraft noise, sport

events, leisure parks etc. Each source has different

characteristics and poses specific problems. For

example, noise can be irritating, disturb sleep and

affect the health of people of all different age groups

(Kanjo, 2010).

There is an increasing body of research linking

prolonged exposure to transport noise to negative

health impacts. A major impact of noise is sleep

disturbance – and disrupted sleep has been linked to

effects on cardiac health. A number of reports have

made direct links between transport noise and

cardiac health. Most work carried out has looked at

impacts of aviation noise. There are links between

children's concentration too. Much of this work has

been carried out in Europe (NOISE PROTECTION).

3 THE ROLE OF WEB SERVICES

To show the role of web services in noise

monitoring systems, we first summarize the

capabilities of these services and then present their

advantages.

Web services provide a method for distributed

applications to access resources that are located on

remote devices in a manner similar to local

resources. Typically, a functionality available on one

server is considered as a method call for an

application running on remote devices (Priyantha et

al., 2008).

In monitoring systems, web services offer some

significant advantages besides enabling a new

method for data exchange.

 Multiple usage: the web service enables sensed

information to be shared across multiple

applications in a very flexible way. The fact

that one service can be consumed by many

users at the same time reduces cost for

duplicating copies of the application to each

client.

 Programmability: the uses of web services

improve the programmability of the system.

The WSDL (Web Service Definition

Language) description of the service can

automatically be parsed by high-level

development tools as Visual Studio and

NetBeans IDE.

 Ease of integration: many network applications

nowadays support web services. It is easy to

integrate the new services into the existing

system. Web service based applications can

run on all kinds of machines from a desktop or

laptop to a mainframe.

The aforementioned advantages prove why web

services in distributed systems are so widespread.

4 RELATED WORKS AND

MOTIVATIONS

Since the request of the European Union for more

detailed noise data and measurements, a significant

number of research has been conducted concerning

noise monitoring and related subjects.

Touhafi et al., 2001 developed a software

package named Euterpe to monitor noise levels in a

cost efficient way. By using this software package,

computer users can investigate noise pollution levels

at any location. The ease of installation and usage is

the significant advantage of the software. With

minimum computer experience, people can set up a

system that can monitor the noise level of their

surroundings.

Cerniglia and Amadasi, 2006 provide a real-time

noise monitoring solution. According to their work,

viewers can see the noise level at a fixed position

both in near real-time mode and offline mode. This

website (see www.citynoise.net) provides real time

video and audio streaming at a pre-determined

location. Automatic warning and report sending are

also considered in the system. Cerniglia proves that

it is possible to monitor noise pollution on a long-

term basis using a web-based application. Although

almost all the objectives of a monitoring system are

met by the system, an application re-using system is

not implemented. Users cannot use this work for

their own purposes.

When taking into account the participation of the

citizen in noise monitoring, Maisonneuve et al.,

2009 presents a new approach, in which urban

people play a significant role in collecting and

sending noise data. By using GPS-equipped mobile

phones, citizens are enabled to measure noise levels

in their daily environment. (Stevens and D’Hondt,

2010) provides a low cost solution for citizens to

measure their personal exposure to noise in their

everyday environment and participate in the creation

of collective noise maps by sharing their geo-

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localized and annotated measurements with the

community. The involvement of citizens promotes

and reduces the cost of the noise-monitoring task.

NoiseSpy (Kanjo, 2010) is a noise monitoring

system, in which Kanjo turns mobile phones into a

low-cost data logger. It allows users to explore a city

area while collaboratively visualizing the noise level

in real time.

A noise monitoring system has been developed

around Brussels airport (www.brusselsairport.be).

This system controls, measures and analyses the

noise produced by the Brussels Airport and outputs a

noise map around the airport. The IDEA project (see

www.idea-project.be) in Belgium focuses in

particular on environmental stressors that have a

very local character such as (ultra) fine particulate

matter and noise. They are also running sound

measurement tests with a network of lower

performance (and thus much cheaper) sensors.

For research based on web services, (Fuyu and

Dogdu, 2006) proposed a new architecture for user

management in federated database system. This

approach is based on web service technologies when

building the components of the system. (Zhu et al.,

2004) states that web services also can be used in the

integration of dynamic data. A service-oriented data

integration architecture (SODIA) is developed to

provide a uniform view of data coming from

autonomous, heterogeneous and distributed data

sources. For the purpose of software sharing over the

Internet, (Yu and Daizhong, 2006) suggests an

approach based on web services. It allows members

of a team, who may work far away, to share their

software resources.

5 STRUCTURE OF THE SYSTEM

In order to promote the participation of urban

citizens in noise pollution monitoring, we propose a

noise monitoring system using web service

technologies. In this system web services are used to

provide access to a recorded sound database. It is

easy for users to query the sound database by calling

defined function calls of the web service. Figure 1

shows the architecture of the system.

5.1 Overview of the System

The system uses microphones, which are attached to

mini computers, to record noise levels at given

locations. Normally, these microphones are placed

in the vicinity of busy streets, dense residences or

airport fly routes. Selected sound data at the nodes

Figure 1: The architecture of the system.

will be sent to a base station (a server). In order to

make the data managing convenient, sensed

information is centralized in a database server where

it is processed and stored.

Internet users who want to add a noise-

monitoring module to their web sites can download

the packed modules from the central server. The

monitoring module provides a map-based interface

that visualizes the sound level at a given location.

These modules are developed based on the formatted

structure of Joomla modules, so it is easy for Joomla

users to install it on their websites. It is also possible

to build a module following the module’s format of

other CMSs (e.g. Drupal).

5.2 System Components

The main components of the system will be

described in the following sections.

5.2.1 Euterpe Software

Euterpe, a software packet developed by A. Touhafi

and his team from the Erasmushogeschool Brussel,

allows the implementation of a low cost sonometer

with of the shelf hardware. The program records

sound waves with a microphone and calculates the

equivalent sound levels in decibel and other

statistical parameters such as the SEL-value and

L05-value. Users can also perform task scheduling

of Euterpe as well as data calibration. Using a

personal computer or a laptop with sound-card, a

microphone and Euterpe, one can quickly monitor

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and analyse environmental sound levels. For

professional purposes Euterpe integrates

functionalities such as logging sound levels in data-

sheets, monitoring and logging the value of a

weather-station, sending messages via GSM and

registering sound fragments.

Figure 2 shows an example output of noise levels

from the Euterpe software.

Figure 2: An example of Euterpe data file.

5.2.2 Data Parsing Component

The main tasks of the parsing program is getting

significant information from Euterpe files and

sending collected data to a server as quickly as

possible. In order to do these tasks, first, the

program must select which is the latest up-to-date

file. Second, the file must be parsed into data records

before being sent to the specific server. All parsed

data are sent to the central station via the selected

channels.

5.2.3 Data Pushing Component

After it is processed, the sound level information is

pushed to a base station by the data-pushing

component. Sound level information is represented

as XML-based messages for ease of use and

platform independence.

5.2.4 Data Collecting Component

Real-time noise monitoring applications require the

data to be retrieved periodically. Because of this the

sound level at the nodes must continuously be sent

to a server. The data-collecting component is used to

gather all the sound information which is recorded at

many different nodes. Sound data authentication is

checked to make sure that the data come from a

registered node. This component also updates the

database continuously during monitoring time. A

database system installed on the server keeps the

sound data for further purposes.

5.2.5 Database Managing Component

The noise-monitoring task produces a large amount

of data. To get this data efficiently processed, it is

necessary to have a good database design and a

strong database system. A MySQL database system

(see www.mysql.com) is a good choice that meets

the database management requirements. Because

MySQL is open and free for download and use, this

database system is suitable for developing the open

systems at a minimum cost and for the maximum

number of users. Combined with a Java-based

framework, MySQL becomes the first choice when

developers want to build internet-based applications.

The query-speed of this database system is high

enough to use it for a real time monitoring system.

5.2.6 Network Services

Web services are used when developing the data

displaying component. These services are deployed

on the server and are used to answer users’ queries

on demand. By using defined standard calls (Pierce

et al., 2008) users can access the database system.

Only a simple web services client is needed to

consume deployed web services. Remote access

clients are not necessary in this monitoring system.

6 IMPLEMENTATION

The main tasks for implementation of the system

consist of developing a noise monitoring system and

building components that consume web services

deployed in the system. The development of the

modules undertaking that tasks is described below.

6.1 The Implementation of Data

Parsing and Data Sending Modules

The data files produced by Euterpe, contain relevant

information, but some of it may be redundant. To

reduce network traffic, only the necessary

information will be transferred through the Internet.

Therefore, these files must be parsed in order to

eliminate the redundancy. To do so, a small program

is developed and runs at the client-side computers.

The program accesses a directory (is set default

by the users) to find what the current working file is.

Making a comparison between the timestamp

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information of the file-name and the current

timestamp of the system determines which file was

last created by Euterpe – this is also the current data

file. After the working file is selected, it is accessed

every 10 seconds to get new data. Each line of the

text file is divided into two fields, timestamp and

sound value. These data fields are formed to an

XML-based message that will be sent to the server

immediately via the internet.

Figure 3: An example of a data message.

6.2 The Implementation of Data

Collecting Module

On the node, sound data is represented as an XML-

message before being transferred. Each data

message contains information about the location of

the microphone where the noise is recorded. Based

on this clue, a program running on the server can

find the sensor node that the message belongs to.

When a message comes in, the server will check

if it is a data message according to the message

header. After that, the remaining part will be broken

into segments based on user-defined tags. From

these segments, all necessary information will be

collected and sent automatically to a database

management system.

6.3 The Implementation of Database

System

The database of the system has two tables, of which

one table is used to keep information related to

nodes. The other is used for storage of measured

data. The node table is updated whenever the

topology of the system changes. The measurement

table keeps all data sent by sensing nodes. Because

the noise level is continuously monitored, the

amount of noise data that is made by this process

becomes bigger and bigger day after day. It is

estimated that each node produces approximate the

number of 31.5 million records per year (one record

is created per second). Therefore, to increase the

performance of the database system in accessing and

querying, a good management mechanism must be

applied when implementing the database system.

MySQL database system provides a table partition

mechanism that is aimed to reduce amount of data

read for SQL operations so that the response time is

reduced as well.

There are two major types of partitioning:

horizontal partitioning which forms of partitioning

segments table rows and vertical partitioning based

on collections of certain columns of the table. The

database system is implemented based on a

horizontal partitioning method, by which the

measurement table is divided into partitions

corresponding to the year when the data was

collected.

6.4 The Implementation of Noise Level

Displaying Component

Joomla, a free and open source content management

system for publishing content to World Wide Web

and Intranets, is widespread, which motivates us to

build a Joomla component that can get noise

information from the database system and show it on

a web page. This component can easily be installed

on websites that are powered by Joomla.

To visualize node locations, a web-based map-

interface plug-in like Google maps is added to the

module. A marker is used to present a node with a

microphone on the map. Markers are placed on the

Google map corresponding to the location where the

real microphones are located.

Sound information is displayed by using graphic

form. On this graph, the y-axis (vertically) shows the

level of sound in decibels (dB), the x-axis

(horizontally) is used for presenting the timeline.

Sound information during monitoring duration is

represented by a zigzag line, which shows the

change of sound level at that location.

Figure 4: An example of real time data displaying.

<? xml version="1.0" encoding="UTF-8" ?>

<data>

<records> <idnode>IDEAErasmus</idnode>

</records>

<idnode>IDEAErasmus</idnode>

</records>

</data>

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7 CONCLUSIONS AND FUTURE

WORK

In this paper, we presented a noise monitoring

system using web services. The contributions of this

work are two-fold. First, we proposed the

architecture and the system components and

described their functionality and their

implementation in detail. Second, we have defined a

web service approach for data sharing between the

server and remote clients and data visualizing. Web

service interfaces are used for controlling database

accessing. Web services technology offers many

advantages for autonomous and distributed systems

like a noise monitoring system.

In the near future, improving the participation of

citizens in noise monitoring is one objective for

developers. The main goals are not only providing

internet users interfaces to access the sound

database, but also enabling them to contribute with

their own sound data. This helps to reduce the cost

for the amount of deployed devices and allows

developers to widen the sensed area. Based on this

work, users will get a better and clearer overview on

noise pollution.

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