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Cassel WL040/Bidgoli-Vol III-Ch-65 September 15, 2003 8:52 Char Count= 0
Wireless Application Protocol (WAP)Wireless Application Protocol (WAP)
Lillian N. Cassel,Villanova UniversityThe Wireless Application Protocol (WAP) 805
The Current Situation 805
Mobile Access to the World Wide Web and Other
Data Resources 805
Standards 806
Wireless Markup Language 807
WML Basics 807
WML Tasks 810Design Considerations 814
Looking Ahead 815
Expectations for Mobile Computing 815
The Role of the Wireless Application Protocol 815
Glossary 815
Cross References 815
References 815
Further Reading 816THE WIRELESS APPLICATION
PROTOCOL (WAP)
WAP is a collection of protocol standards whose purpose is
to enable communication between handheld wireless de-
vices and Internet-based service providers. These service
providers include Web servers providing content format-
ted especially for small wireless devices and other service
providers who target wireless devices exclusively.
This set of standards builds on existing standards,
reusing or modifying them where necessary to address the
special needs of the handheld wireless community. The
particular limitations of the wireless world include greatly
restricted bandwidth, nonrobust connections, signal secu-
rity limitations, the small screens on most devices, limited
battery life, and restricted input options. Processor power
and memory are other limitations for most target devices
(Wireless Application Protocol Wireless Session Protocal
Specification, 1999).The Current Situation
The mobile telephone industry is currently suffering from
disparities in standards that limit the usefulness of phones
as they travel from one location to another. Currently,
wireless system providers in the United States adhere
to one of four different standards: IS-95 CDMA, TDMA,
GSM, or IDEN. CDMA is code division multiple access
and is the basis of the third generation (3G) wireless trans-
mission technologies WCDMA and CDMA2000. TDMA
is time division multiple access, in which each convers-
ation has access to the carrier frequency only part of the
time. There are a number of implementations of TDMA,
including the digital American mobile system (D-AMPS),
the global system for mobile communications (GSM),
personal digital cellular (PDC), and the integrated digi-
tal enhanced network, (iDEN). GSM is uniformly used
throughout Europe allowing systems to roam and retain
service over large areas. GSM is also the standard in use
in most African nations (Digital Mobile Phone Networks
in Africa). PDC is the standard for cell phone access in
Japan, where its widespread use makes it the second most
used standard in the world. IDEN is a proprietary stan-
dard from Motorola. The lack of interoperability amongthe various standards is a serious limitation, restricting
access as users move about (Dornan, n.d.a.).
An important characteristic of the communication
mode is the basic model for connectivity. Connection
can be either packet-switched or circuit-switched. Circuit-
switched means that a connected user consumes band-
width for as long as the connection is maintained. Most
systems charge by connection time, reflecting the con-
sumption of bandwidth. Packet-switched connectivity
means that the device consumes resources only when ac-
tually sending or receiving a transmission. There is no
reason to disconnect the device from the network. This
always-on feature has significant consequences for wire-
less service providers. As a result, the most actively used
wireless services are those in Japan, where cell phone use
is pervasive and services are always available, without the
need to establish a connection.
Mobile phone networks are moving toward advanced
technologies, which will bring packet-based communi-
cation to the systems used outside Japan. Expectations
are that the always-on characteristic will drive interest
in and use of emerging applications available to mobile
phone users. If the experience in Japan translates into
usage patterns in the rest of the world, the demand for
applications will grow at a great rate in the near future.
Developed to run over any and all of the mobile device
transmission methods, the wireless application protocol
suite is the common set of standards that allows these
applications to be available to all wireless devices.MOBILE ACCESS TO THE WORLD WIDE
WEB AND OTHER DATA RESOURCES
The World Wide Web has become a utility, taken for
granted as an information and communication resource.
Similarly, the mobile communication device—whether
phone or personal digital assistant—has become a part
of the environment for many people. It is natural to
look to combine these two. Access to existing Web pages
is one goal of emerging standards and technologies for
handheld, mobile, wireless devices. However, these de-
vices offer opportunities to provide services and informa-
tion feeds beyond what the Web provides. Web pages are
dynamic, but they are not very responsive to the location805