MICROELECTRONIC ENGINEERING RESEARCH CONFERENCE 2001
Mobile Internet and Wireless Applications
WAP.FILMLISTEN.NO
Thorbjørn Rusnes
Abstract – In this project we have used an online web
site, and converted it into a site to use on wireless
equipment. The focus has been on the current
standard, and ways to use this technology today. This
work ends up with a working model of a web site for
WAP ready for release. Some of the limitations and
problems with current version are addressed. Today
there are two major competitors in the wireless
Internet race, WAP and iMODE. This work has a
major focus on WAP, but is not locked to it.
I. INTRODUCTION
OBILE INTERNET is just in its start phase and
already there are lots of expectations among the
public on how its behaviour and use should be. The
situation for the user is a huge amount of different
equipment with different support of the technology. Users
expect to find the same kind of functions in a wireless
device as they do in their home computer. At the same
time there is still three different versions of mobile
Internet, WAP [1], iMODE [2] and HDML [3]. Where
WAP and iMODE are the two versions most successful,
WAP amongst the providers and iMODE has most users.
All technologies are today depended on a
gateway to do the translation of the request and the
response. This minimizes the amount of data sent on the
slow wireless link.
M
Client
Gateway
Encoded Request
WAE
User
agent
Origin Server
Request
Encoders
and
Decoders
Encoded Response
Response
CGI
Scripts
etc
Content
There has been a lot of research on use and
implementation of different wireless technologies, but not
on the actual use- and making of applications for it, and
the interaction between the wireless equipment and the
content server.
WAP applications need to be specially designed
for the mobile equipment and its limitations like limited
memory, CPU capacity, a small screen and sometimes
few keys, all with the lack of equipment descriptions
variables. At the same time it is important not to lock the
server side code to a specific type, but to design it so it
easily can adopt new changes and technologies.
In this research is an application was developed
for a Norwegian online entertainment site [4] that uses
most traditional online technology. Database interaction,
text and graphics presentation and user authentication is
tested. The research started was based on a request form a
Norwegian company to develop a WAP version of their
current web site, where most of their functions where
available. The server side code had to be as general as
possible for this database, so that new technologies easily
could be added.
In an entertainment environment the majority of
information is based around pictures and multimedia
content. The current version of WAP [1] only supports
simple graphics and text. There is also a lot of text that
can be displayed if equipment supports it.
II. IMPLEMENTATION
This research focused on the actual implementation of the
application and how it would work on wireless
equipment. Issues on converting an online site to a
wireless application was discussed and addressed
accordingly.
One of the biggest challenges in wireless
application is to design and adjust the output so that it will
suit the used equipment. Screen size and memory capacity
is the most important factors to consider, and with so
many different types of equipment with few variables
telling the system how to react. Even tough the WAP
specification has included a user agent type description
specification in WAP1.1, it is still only a recommendation
and very few use it. Still some variables can be used
given they only are set to control whether to allow the
minimum requirements or not. A compromised solution
was used to cope with most cases in today’s equipment.
The solution was based on using multiple variables, some
for acceptance and other for exception handling.
When making an application for this kind of
equipment it is important to open for the use of different
mark-up languages. Therefore a way of integrating any
mark-up language into this wireless application is
proposed. This means keeping all the mark-up code in the
template files and leave the program scripts for gathering
information from the database. A set of special tags is
used for controlling the server side scripts to produce the
correct output. One tag type where based on the comment
MICROELECTRONIC ENGINEERING RESEARCH CONFERENCE 1999
tag,  and allows the designer to
group code that are identical and dependent of the
numbers of output lines from the database. This tag needs
a start and stop tag! The other tag type is a custom made
one and follows the syntax, <%tagname%>. This tag
tells the system what kind of information to replace the
tag with. All possible tags are to be found in the user
guide on how to use the system.
In many online applications today, there is a
request for authentication. There are different types of
authentication available. The best one to use today is
HTTP authentication, using a .htaccess file. This will
deny access to particular directories on the server without
correct username and password. This proved not to be a
good solution for this project. There were too many
variables in the database that controls the login to use http
authentication. The alternative is an applicationcontrolled authentication, and is usually based upon
cookies. It will give a more personal site and
advertisements can also be more focused on the details
about the authenticated user. A secure authentication
requires some form of feedback from the client to identify
it. This feedback is usually signed with a digest produced
at login containing special information only valid for the
current user. In today’s WAP version there are no support
for cookies or local variables in the phone to store a key
for digest generation. The idea is to store a special digest
generated for the login session in the users equipment or
cookie for proof of identity. The lack of cookie support
forces the id to be stored in local memory of phone. This
memory is unfortunately a global memory, and any site
accessed after a login can read this variable and use it. On
the bright side, this variable is deleted when a card uses
newcontext=”true” or cache is cleared.
Mobile phones from the same provider network
proved to have the same IP-address, one reason being the
limitation of IP-addresses in the current IP version.
Mobile equipment is given an internal “illegal” Internet
address, and external it uses the gateway address.
Together with the lack of id numbers or subscriber
number there are no good user id to identify the user or
session. This id is very often used for MD5 generation of
digest in login and authentication.
Pictures are big part of today’s Internet,
especially filmlisten’s news and articles. But presenting
these pictures on a wireless device generates some new
problems. The picture format used in web usually has to
be converted and resized into wireless bitmap. We found
the use if ImageMagick [7] to be really useful. Some
experimenting of options to use gave good results. Even
though most phones are said to support 100 pixels wide
pictures, we found it necessary to reduce the picture size
to 80 pixels wide. This reduces some of the details in
some pictures but allows more equipment to accept them.
III. CONCLUSIONS
As a result of this research we have come up with one
suggestion, implementation of wireless applications
without locking the output code to one technology. There
is no doubt that the current standard needs modification to
meet the demands of the future. A closer integration with
traditional web is an important part of this.
A problem in development of wireless
applications using WAP 1.1 is not all functions proposed
in the standard is available in the user equipment. There
are also too many differences in both the browser and the
gateway that handles the compiling. The result is that the
application has to use the basic functions only, the
functions supported by every gateway and equipment
used.
It is important that wireless Internet has the same
support for cookies as traditional browsers. Variables
stored in phone should also be stored local to the domain,
not global. Even though IP-addresses can be spoofed, it
increases the security.
Some of the problems and
limitations in current WAP standard have
been addressed and some proposed
solutions are found in the new standard
of WAP, WAP 2.0. The question is only,
when will it all be available to the
public?
Most of all check out the result
of this work on wap.filmlisten.no!
IV. REFERENCES
[1] www.wapforum.org WAP 1.x
[2] www.nttdocomo.com iMODE
[3] www.openwave.com HDML
[4] www.filmlisten.no FilmListen
[5] “The wireless application Protocol, Writing applications for
the mobile Internet” by Sandeep Singhal, Thomas
Bridgman, Lalitha Suryanarayana, Daniel Mauney, Jari
Alvinen, David Bevis, Jim Chan and Stefan Hild. AddisonWeisley October 2000.
[6] “www.z-y-g-o.com/wsec.html” Wireless security by Angus
Wood
[7] ”www.imagemagick.org” Image magick