20.5 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.