A Sample Application
Our work embodies most of the suggestions in the previous section.
In this section, we describe a sample application. Using this
application, we show that in order to create WAP services or
applications in a PC, we have to install a System Developers Kit (SDK)
and simulator, such as those from Nokia, Ericsson, or Phone.com. For
WAP applications that require database, a WAP-enabled
transaction-processing model is more efficient
than other models described in the literature because it is implemented
as an additional layer on top of the MDBS that handles mobile accessing
and long-lived transactions in a multilayered approach. In integration,
a local server may be needed, such as the Microsoft Personal Web Server
(PWS), IIS, Apache, Xitami, or any other type of server for testing the
access speed in LDBS. A range of database integration tools can be used
for WAP development, such as Microsoft Active Server Pages (ASP), Perl,
etc. We have installed Nokia Mobile Internet Toolkit, Version 3.0,
which supports WAP standards, authored by the WAP Forum, as well as
other specifications authored by other organizations, and used ASP for
programming.
Normally, the mobile phone emulator is capable of
viewing WAP content in different ways. It can either load files that
are stored in the PC directly or access files stored on Web servers and
pretending to be a gateway or access files via a real WAP gateway. We
can create a profile that specifies a connection to a particular WAP
gateway in connectionless mode, another to the same gateway in secure
connectionless mode, a third to the same gateway over a proxy server,
and a fourth to a different-origin server using a direct HTTP
connection.
In an attempt to explore the system, application, and
user issues associated with the development of such mobile
applications, we have considered the hotel booking system in Malaysia.
As this research is relatively new, the default values of various
parameters are educated guesses. Message transmission time has been
calculated assuming that the static network is a 100-Mbps Ethernet.
Current cellular technology offers a limited bandwidth on the order of
10 kbps, whereas current wireless LAN technology offers a bandwidth on
the order of 10 Mbps; these numbers are most likely to change in the
future. The hotel booking system consists of interaction with other
hotel databases as our system needs to access other participating hotel
databases to get room availability and also to send confirmation to
members who book through the system.
The hotel booking process is done through
WAP-enabled mobile phones by getting input from the member, such as
check-in date, duration of stay in the hotel, number of rooms to book,
etc. A member makes a booking to the hotel of his or her choice. The
system will automatically check for room availability. If the system
check finds that there are no rooms available, then the system will
cancel the booking, inform the mobile user of the unsuccessful booking,
and request him to book again. We have tested our WAP-enabled
transaction model with a few existing hotel databases. The size of
local database at each site, which has a direct effect on the overall
performance of the system, can be varied. The global workload may
consist of randomly generated global queries, spanning over a random
number of sites. Each operation of a subtransaction (read, write,
commit, or abort) may require data or acknowledgments sent from the
local DBMS. The frequency of messages depends on the quality of the
network link. In order to determine the effectiveness of our
WAP-enabled transaction-processing model, several parameters are varied
for different simulation runs.
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