Emersion of concepts such as ubiquitous computing has leaded to development
of new type of geospatial information system, which is known as mobile
GIS. Mobile GIS refers to the access and use of GIS data and functionalities
through mobile and wireless devices. Currently, mobile GIS and relevant
technologies, techniques and applications are widely under research and
investigation. Various explanations and examples are available, e.g.,
Derekenaris et al. (2001), Montoya (2003), Casademont et al.
(2004), Yuna et al. (2006), Toninelli et al. (2007) and
Yin et al. (2006).
The most important challenge of designers for development of mobile GIS
applications is the restricted resources of mobile devices (Kupper, 2005).
In fact, designers can no longer count on adequate amount of memory, processing
power, etc. in mobile devices. Additionally, the number and type of mobile
devices is increasing and designers must concern on the affects of nuances
among mobile devices.
Locating and executing business logic on remote servers is a solution
for mobile devices limitations, particularly memory and processing resources.
There are also, many applications requiring client-server architecture,
in nature, to provide users with access to data, functionalities and services
which are provided by different servers and data providers. Emergency
management, Natural Resource Management and Location Based Services (LBS)
can be named as some examples of such applications.
Considering emergency management as a sample, according to the SDI conceptual
model for emergency management developed by Mansourian et al. (2006)
and also a further interoperable system architecture for emergency response
proposed by Mansourian and Taleai (2008), each of the emergency management
organizations should update some parts of spatial data describing current
emergency situations during their emergency response operations. They
should also provide spatial services and functionalities required for
better decision-making. These spatial data, services and functionalities
should be shared to be accessible for wider emergency management community
for a coordinated and knowledge-based emergency response. Using such up-to-date
spatial data, functionalities and services which are accessible to emergency
workers via mobile GIS, they can make the best in-field decision for any
operation. Mobile GIS is also a proper tool for in-field data collection
to update organizations data servers.
In such applications, due to the nuances among different mobile devices,
each mobile device requires its own specific server designation and implementation.
This situation makes mobile GIS not to be applicable in practice. Developing
mobile GIS systems using Web services technologies is a proposed solution
to the problem.
Web services are key technologies allowing the application`s business
logic, or some parts of that, to run on remote servers, independent of
the mobile device`s computational resource limitations. Further more,
Web services provide a variety of mobile devices with effectively access
to the same functionality or business logic on remote servers. By locating
and executing business logic on remote servers, the developers can focus
on just developing user interfaces, which are the gateway between the
user and the business logic, with respect to the specific mobile devices`
characteristics. By implementing Web services on the servers of emergency
management organizations, client applications on the hand-held devices
of emergency workers can access the services of different organizations
to use different functionalities and data which are provided by other
In the context of an ongoing research project in K.N. Toosi University
of Technology, a prototype mobile GIS system for emergency management
has been designed and developed, based on Web services technologies. In
this study the outcomes of the project is depicted and the proposition
MATERIALS AND METHODS
This study was conducted in the context of a research project numbered
PM/2251 granted to the authors from K.N.Toosi University of Technology,
Iran, in August 2007. Here, describes the main technologies and frameworks
utilized for development of the studying system.
Web services technologies: Web services technologies are realization
of a software design pattern called service-oriented architecture (SOA).
From the SOA point of view software architecture is composed of services
(Zimmermann et al., 2004). The services are applications which
present piece of functionality that fulfill users (human or software package)
needs and requirements. SOA is a conceptual architecture for implementing
services with the following characteristics (Cerami, 2002):
The service is generally, implemented as a course-grained, discoverable
software entity that exists as a single instance and interacts with applications
and other services through a loosely coupled, message-based communication
model. The service is a software entity that is available over the Internet
or private (intranet) networks; uses a standardized messaging system;
is not tied to any one operating system or programming language; is self-describing
via a common grammar; and is discoverable via a simple find mechanism
Figure 1 shows 3 major roles in SOA: Service providers
which implement their services and publish them on the internet/networks;
Service requesters that utilize the available services to fulfill their
requirement; and Service registries which are directories for services
and service providers can publish their services by registering them in
it and service requesters can search for appropriate service in it. SOA
works based on a publish-find-bind model.
Web services are implemented using a collection of standards. These standards,
when considered together, form what is widely referred to as the Web services
protocol stack. Figure 2 shows the seven distinct layers
of the Web services stack, which are grouped into three levels (Marks
and Werrell, 2003). Each level indicates a level of maturity for the layers
it contains. These levels represent a framework that can be used to evaluate
the maturity of Web services standards today and can also be used to monitor
how Web services standards progress over the medium to long term.
||Web services major roles
||Web service protocol stack (Marks and Werrell, 2003)
The enabling standards level contains network transport protocols and meta-language
layers. The layers within the enabling standards level contain well-defined
and accepted standards and protocols that are widely used to support mission-critical
business application such as TCP/IP, HTTP and XML.
The evolving standards level contains layers for SOAP (Simple Object
Access Protocol or Service-Oriented Access Protocol), WSDL (Web ServiceDefinition
Language) and UDDI (Universal Description, Discovery and Integration)
which all together form the core standards for deployment of Web services.
The services communication layer uses SOAP as a lightweight protocol for
exchange of information in a decentralized, distributed computing environment.
SOAP is an XML-based protocol that allows communication between multiple
computer architectures, languages and operating systems. The service description
layer is where WSDL is used as a common XML framework for describing a
Web service. A WSDL document describes a set of messages in terms of what
they contain and how they are exchanged. In addition to describing the
message contents, WSDL defines where the Web service is available and
what communication protocol is used to talk to the service. In other words,
the WSDL file defines all the information required to invoke a Web service.
The UDDI specification defines a data structure standard for describing
organizational entities and the services they provide using XML (Service
Publishing and Discovery Layer). UDDI provides high-level business information
that complements the information contained in a WSDL document (Apte and
The emerging standards level has the least well-defined capabilities.
This level represents proposed standards that are promoted by individual
vendors, have not yet gained broader endorsement or acceptance in the
wider Web services community and have not been adopted as open standards
for development by key standards bodies such as the W3C and OASIS.
There are many examples of implementation and utilization of Web services
technologies such as: Wang et al. (2004), Oh and Fox (2007), Murakamia
et al. (2007), Votisa et al. (2008) and Gyimesi (2008).
In order to develop a Web service environment, there are two development
lines with respect to service providers and service requesters. Service
providers in order to implement and publish their own Web services should
first develop the core functionality of the services. During the first
step, service providers may develop the core functionality from scratch
or they may connect to an existing legacy system or application. At the
next step, they should develop a service wrapper for the core functionality.
This usually could be a SOAP service wrapper. Such capabilities are provided
in the most of software development platforms such as Microsoft Net framework
of Microsoft and J2EE of Sun Microsystems. Service providers present a
service description as a WSDL document afterward. Then, they need to deploy
the services on some Web servers over the internet. Finally, service providers
need to publish the existence and specifications of their new service.
This usually means publishing data to a global UDDI directory or perhaps
a private UDDI directory specific to their company.
In a web service environment, in order for service requesters to exploit
the published Web services, those services relevant to the requirements
should be first identified and discovered. So, this first step usually
involves searching the UDDI for services. Once appropriate services have
identified, the next step is to locate a service description as a WSDL
document. Third, service requesters must create a client application.
Finally, they should run the client applications to actually invoke the
General architecture of mobile GIS for emergency management: Variety
of different architectures is possible when developing mobile Web services
applications. Considering the requirements of emergency management, appropriate
architecture of mobile GIS system for emergency management is suggested
as Fig. 3. Figure 3 shows the block
diagram architecture of the system.
The architecture is composed of 6 main components as follow:
||Position determination components
In the architecture of Fig. 3, hand-held devices are
used by emergency workers to interact with the system. The hand-held device
is a part of system which mobile GIS client application should be installed
and run on it. The mobile GIS client application presents a front-end user interface
that presents information to emergency workers and captures their input
data. Position determination component refers to the component that determines
the location of hand-held device in real time. The hand-held devices exploit the wireless network, the gateway and the
internet to interact with mobile GIS Web services, which are installed
and run on the server. The server is a computer which is used by the organization to deliver
data and functionalities to the client applications. The server is connected
to the internet. The internet is also connecting to the wireless network
thorough the gateway which is a translator between these two types of
network. Each of mentioned components is briefly described as follow:
Hand-held device: The hand-held devices are different from desktop
or laptop computers. They have limited display monitor and data manipulation
facilities such as mouse and keyboard. Mobile devices are two major categories:
PDAs/Pocket PCS and smart phones. Smart phones are mobile phones with
some extra computer-liked functions such as accessing and surfing the
Web, data upload and download, etc. In contrast to smart phone, PDAs/Pocket
PCS are small and restricted resources computers which use some light
weight operating systems such as Microsoft Windows CE, Palm OS or Symbian`s
EPOC. Currently, these two types of hand-held devices are converging to
each other as sometime it`s hard to distinguish them from each other.
A hand-held device in order to be useful for an emergency management mobile
GIS system should have the ability to connect to a Web-based server through
a wireless network.
Position determination components: Position determination components
refer to the components that determine the location of a mobile devices
in real time. Two approaches are used to compute a mobile user`s position,
which are hand-held based and network based.
Some hybrid approaches are used as well, where measurement and computations
are split between the terminal and the network (Pashtan, 2005). Three
of the best methods which can provide emergency management with accurate
positioning are the observed time difference of arrival (OTDOA), uplink
time difference of arrival (U-TDOA) and Global Positioning System (GPS).
Server: Server is another component of a emergency management
mobile GIS system.
||Overall architecture of the prototype mobile GIS system
for emergency management
In fact involving organizations in emergency management
should have some Web services to interact with mobile GIS client applications
of emergency workers. These services work on server computers of the organizations.
Wireless Network: Wireless network is the underlying infrastructure
of the mobile GIS system for emergency management. Thorough the wireless
networks, the gateway and wired network, hand-held devices of emergency
workers can communicate with servers.
Wireless networks have evolved across the time. According to Kupper (2005)
that investigates different generations of wireless networks, 2.5, 3 and
4 G of wireless networks are the proper media to implement mobile GIS
application for emergency management. However, it should be noted that
mobile GIS works in a much more challenging wireless network environment
than the wired network environment. At least, currently 2.5 and 3 G wireless
networks which are available and operational have some restrictions including
limited bandwidth, connection latency, unstable connectivity, etc.
Any wireless data network can be used as the infrastructure to access
the Web. However, considering the low bandwidth of the wireless networks
and small screen and user-interface of hand-held devices, the Web content
should be mobilized. Nowadays, several standards and specification have
developed for the wireless Web, including C-HTML (Compact HTML), Web Clipping,
HDML (Hand-held Device Market Language), WAP (Wireless Application Protocol
), XHTML, etc. that can be used for accessing Web thorough the wireless
Internet: Internet is considered as another component of the mobile
GIS system. It connects server computers of the organizations, involved
in emergency management to the wireless network.
Gateway: The gateway is a piece of middleware that links the wireless
network to the internet. It basically gives the wireless network the ability
to access the internet contents. The gateway (e.g., Web gateway service
or WAP gateway service) acts as an interpreter, which translates the internet
content for mobile devices and vice versa.
Design and development of a prototype mobile GIS system for emergency
management: As a part of the research, a prototype mobile GIS system
was developed, using Web services technologies, in order to investigate
integration of mobile GIS and Web services technologies. The prototype
system was developed for emergency management.
From a software architecture point of view, the system has two main groups
of software packages: mobile GIS client applications and mobile GIS Web
services. It is obvious that organizations involved in emergency response,
may develop some mobile GIS Web services and some mobile GIS client applications,
based on their own requirements. Since, there are several applications
required for emergency management, in this research, a prototype system
based on a predefined scenario and application was developed, that satisfied
fire organization. Based on the scenario, fire organization as one of
the participating organizations in emergency response is going to present
following functionalities to its firefighters in the operation area:
||The ability to view a map that contains buildings, road
network and important buildings such as gas stations, hospitals, schools,
||The ability to determine a firefighter`s location and showing the
location on the map to him/her.
||The ability to present up-to-date spatial data about the burning
area to the firefighter in the field.
||The ability to update the database of fire organization after finishing
||The ability to use the municipality data about the closed roads.
||The ability to find optimum path from current location to the burning
area, based on usable roads.
In order to develop a prototype system based on described functionalities
the system was split into three distinct packages:
||Mobile GIS client application: Provides firefighter
with an interface to interact with the system;
||Firefighting Web service: Is a web service, which is responsible
for delivering information about burning area to firemen. Also, the
service is responsible for receiving the information of firefighter
about their finished operations and updating the database of fire
organization by that information.
||Road network Web service: A web service, which is located at the
municipality and is responsible to distribute the information about
closed roads during an emergency. It also provides users with optimum
path finding analysis.
In fact many challenges exist for developing the mentioned packages:
(i) the Web services have to provide information and functionalities for
mobile devices over the wireless network and (ii) the mobile GIS client
application have to be run over a restricted resource hand-held device.
The first problem relates to the wireless network. As mentioned earlier,
a variety of wireless networks are available now, each of which has unique
characteristics that make it appropriate for specific applications. Meanwhile,
mobile GIS system should address many issues with respect to wireless
network characteristics including (Kupper, 2005):
||Network coverage: Mobile devices do not have network
connectivity everywhere at all times.
||Latency: Wireless network connections are slow and some are slower
than others. Few wireless connections achieve their advertised bandwidth
and also there are still errors in connections that increase the latency.
||Power: Wireless networks consume power at a voracious rate. For
every bit of information transmitted or received, an amount of power
||High costs: Wireless usage rates are expensive. Other than fixed
costs of an enterprise WLAN, wireless network access involves a service
provider who may charge by the minute, by the amount of bandwidth
used, or through a flat rate.
Considering the mentioned issues, most mobile applications today adhere
to one of the two distinct possibilities (Chatterjee and Webber, 2004):
||Systems in which client applications require an always
on network connectivity and
||Systems that function properly without the wireless network at all,
but simply synchronize their data through a network-connected PC.
In general, both of these systems fail to satisfy the requirements of
emergency worker in the defined scenario. Mobile GIS client applications,
based only on offline synchronization capabilities, do not leverage wireless
connectivity to provide real-time access to the most up-to-date information
of the organizations. On the other hand, Mobile GIS client applications
that heavily use the wireless network provides real-time access while
decreasing application latency and increasing usage costs. Therefore,
in this research an intermediate approach was adopted to develop the proper
system for emergency management. This intermediate approach has following
The mobile GIS client application is designed in the way that it can
handle some of the requirements of the emergency workers, independent
of Web service of fire organization. The client application has most of
the important data about the operation area including buildings, road
networks and important. The client application also is capable of showing
the workers current position on the map using an intrinsic GPS receiver
of the hand-held device. The application also has simple GIS functionalities
such as zoom, pan, identify etc. The mobile client with these functionalities
can provide emergency workers with some part of information in different
situations without the need to a wireless connection to the firefighting
or municipality services.
The mobile GIS client is capable of using firefighting Web service to
retrieve the information about burning area and show this information
on the map. Additionally, emergency workers can update the database of
fire organization thorough the mobile GIS application and firefighting
Web service. These functionalities are accessible only if the connection
to wireless network is established and worked in a proper manner.
The mobile GIS client also is capable of using road network Web service
of municipality to show the closed roads on the map. This functionality
is accessible only if the connection to wireless network is established
and worked in a proper manner as well.
The firefighting Web service uses transactions in order to update databases
of fire organization. Therefore, if the connection between the server
and the client is broken the database will not affect and the user should
start over database updating; as there is no real means of saving information
prior to a transaction completing.
Another problem for developing mobile GIS systems is that hand-held devices
have limited resources dictated by their power and size constraints. Therefore,
for developing the mobile GIS system, the simple functionalities are implemented
at the mobile GIS client application and the more complex ones such as
network analysis are implemented at the Web services.
Microsoft Net Framework and Sun Microsystems` Java 2 Enterprise Edition
(J2EE) provide excellent platforms for developing Web service applications.
In addition, Microsoft Net Compact Framework (CF) and Java 2 Micro Edition
(J2ME) are two famous platforms for developing mobile applications. In
this research, Microsoft Net Framework is used to develop the firefighting
Web service and the road network Web service. Microsoft Net CF is also
used to develop the mobile GIS client application. C# is exploited as
programming language for developing the system.
The Microsoft Net Framework is an integral Microsoft Windows component
for building and running the next generation of software applications
and Extensible Markup Language (XML) Web services.
Firefighting Web service. a: general information about
the Web service generated by Net Framework;
b: WSDL document of firefighting Web service
||Mobile GIS client application
The Net Framework consists
of two main parts: the Common Language Runtime (CLR) and a unified set
of class libraries, including ASPNet for Web applications and Web services,
Windows Forms for smart client applications and ADONet for loosely coupled
data access. The Microsoft Net Compact Framework is the smart device development
framework for Microsoft Net, bringing the world of managed code and XML
Web services to devices. The Net Compact Framework is a rich subset of
the Net Framework, thus providing the same benefits as the Net Framework.
But the Net Compact Framework is designed specifically for resource-constrained
devices, such as PDAs and smart mobile phones. The Net Compact Framework
greatly simplifies the process of creating and deploying applications
to mobile devices while also allowing the developer to take full advantage
of the capabilities of the device.
Firefighting Web service presents Get Fired Area() and Operation Report()
functions. The Get Fired Area() can be used by mobile GIS client application
to retrieve the burning area of a specific zone. The zone is introduced
to the Firefighting Web service by drawing a bounding box. The Get Fired
Area() returns an XML file which contains spatial and non-spatial information
about burning areas. The Operation Report() can be used to update the
database of fire organization by mobile GIS client application. The Operation
Report() returns a Boolean variable which indicate if the update transaction
is finished successfully. Fig. 4a illustrates the required
information about the firefighting Web service that is generated by Net
Framework. Fig. 4b shows the WSDL document of the firefighting
The road network Web service presents Get Closed Points() and Optimum
Path() functions. The Get Closed Points() gets the bounding box parameters,
specified by the mobile GIS client and returns spatial and non-spatial
information about closed point on the road network within the area. The
Optimum Path() can be used for determining the optimum path based on the
user inputs (start and end points on the network) and closed roads constrains.
The Web service returns an XML file, which contains the spatial information
about the optimum path.
The mobile GIS client application presents zoom, pan, identify and some
other simple functionalities to firefighter. Figure 5a
shows the simple map of the client application which contains building
and network layer of an area in Tehran city (Between Shahrak Ghods and
Vanak Sq.). Figure 5b shows a map of client application
in which burning area is marked. The information about burning area is
retrieved from firefighting Web service using SOAP messaging mechanism.
Figure 5c shows the information about closed roads which
is retrieved using Get Closed Point() function of road network Web service.
Fig. 5d illustrates optimum path between the current
location of firefighters and a burning area. As Fig. 5d
shows, the optimum path is determined with respect to closed roads.
Mobile GIS can be exploited as a tool, which provides emergency workers
with the ability to update required data for emergency management, particularly
in response phase. Also, mobile GIS with the ability to access required
spatial data can support in-field decision making of emergency worker.
Considering the specific characteristics of hand-held devices and wireless
networks as well as requirements of emergency workers, in this study Web
services was suggested as the appropriate technologies that can facilitate
the development of suitable mobile GIS system for emergency management.
Web services allow a part of mobile GIS system`s business logic to run
on servers, independent of the mobile device`s computational resource
limitations. Web services provide a variety of mobile devices with effectively
access to the same functionality or business logic on remote servers.
By implementing Web services on the servers of emergency management organizations,
client applications on the hand-held devices of emergency workers can
access the services of different organizations and therefore use different
functionalities and data which are provided by other organizations.
In order to evaluate the usefulness of using Web services technologies
for developing mobile GIS system for emergency management, a general architecture
for mobile GIS system for emergency management was proposed and a prototype
system based on the proposed architecture was developed. The prototype
system was developed based on a defined scenario for firefighters in fire
organization. Using the developed system, firefighters can access to some
basic functionalities and data of the area. Additionally, they can access
up-to-date data about burning area from the Web service of fire organization.
They can access to the most up-to-date data about closed roads using the
Web service of municipality. The Web service of municipality also provides
firefighters and emergency workers of other organizations with the ability
to find the shortest path to a destination with respect to the open and
closed roads during the emergency.
The development of prototype system shows that using Web services technologies
as underlying technologies for developing mobile GIS system for emergency
management can effectively improve the quality and applicability of the
From the results of the case study, it can be concluded that using Web
services technologies, new generations of mobile GIS systems can be developed
in which irrespective of mobile devices specifications, applications at
the server side can be designed and implemented. Mobile clients can also
easily access the servers, data and functionalities and use them via just
a specific mobile device interface. Utilizing Web services technologies
are new in developing mobile GIS systems and therefore more research and
experiments are needed to test these technologies. Also, in future investigations,
integration of Web services technologies with recent activities of international
standard organizations such as OGC in the context of geospatial Web services
and Open LS should be considered for developing mobile GIS systems.