WAP: Now And Into The Future!
by Christoffer Andersson
February 14 2001
As WAP services are
launched in countries all over the world, some people are getting their first
experiences of Mobile Internet. There is an incredible activity among WML
developers today, and everyone wants to jump on the bandwagon. Still one can
hear some HTML-developers being grumpy about abandoning their favorite markup
language, and learning a new one that is extremely unforgiving to syntax
errors. Others say that higher bitrate technologies, like GPRS and 3G will take
away the need for WAP in the future. I just wanted to go through a couple of
reasons why I think that WAP is here to stay and how it is likely to evolve in
the future. There are after all many other things to WAP than the markup
language.
What's New In WAP 1.2.1
Today most of the WAP
content is written for WAP 1.1 compliant phones, and we are seeing WAP 1.2.1
finalized in standardization. Content for the new standard is currently being
developed and developers are just waiting for the phones. Examples of a 1.2.1
compliant phone is the R520 from Ericsson. The main features that
will be introduced in 1.2.1 are:
Push - This enables trusted
applications servers to initiate transmission of information to WAP devices. An
example could be getting weather updates to let users know that a storm is
approaching. This is especially useful for packet networks like GPRS, where
users are always online.
Wireless Identity Module (WIM) - Can be used to store user specific parameters. For GSM/GPRS/WCDMA
phones the SIM card can be used as WIM module and make it easier to implement
security solutions.
UAProf - Introduces User Agent Profiles that can be used to advertise handset capabilities to
applications servers and other entities. This means that content can be better
adapted for different types of devices.
For a comprehensive
discussion on these updates and others, check out the WapForum website.
WAP 1.2.1 also includes a number of smaller adjustments which
takes away ambiguities.
WAP, Next Generation (NG)
WAP's next step has
the working title WAP-NG (sometimes called WAP 2.0 and targeted to be finalized
by mid-2001), and will be a larger step. This is viewed to be the standard that
initial 3G handsets will use, and lots of work is put into it already. NTT
DoCoMo is heavily involved in this in order to find a solution that can be used
in their iMode service as well. Today the massively popular Japanese service
uses a proprietary HTML-derivative, called c-HTML, which has caused some
worries, among WAP (WML) developers.
iMode has experienced a tremendous growth (around 20 Million users in less than
two years) and one reason is that c-HTML is very easy to get started with. WML,
on the other hand, has been seen as bulky and cumbersome by some developers.
The issue with HTML and HTML-derivatives has so far been the lack of strict
rules for content description. When designing for small devices, that all have
different form factors and screen sizes, it is important to be able to control
the way content is presented in a more detailed way. WML is derived from the
rules of XML, a generic content description framework. Now the WWW Consortium,
W3C, is working on ways to apply XML rules into a revised HTML standard, XHTML.
The WAP forum is working closely with W3C in this effort, and it is foreseen
that WAP 2.0 will support both WML and XHTML. This ensures that content
developed today will also be viewable on future devices. The following picture
shows the evolution of the markup languages.
The issue is a bit complicated and this
picture is of course not perfect. XML is really a framework and set of rules,
from which WML and XHTML are derived. As this version of the WAP standard is
NOT yet finalized, these things are still not carved in stone. The WAP Forum
aims to finalize the standardization work by mid-2001 and history has shown
that handsets then should start to appear 6-12 months later.
Beyond Markup Languages
The discussion above is
very typical for WAP today, where everything circulates around the markup
language and what we can see. In order to elaborate on why WAP will be a major
force even as bitrates get higher and screens get bigger, we will now look into
WAP under the hood.
One heavy reason to WAP's
continued presence as a mass market access, is that all major phone
manufacturers have committed to put WAP into all upcoming phones. Apart from
that I'd like to give four main aspects of WAP who are important, now and in
the future:
Content adaptation - Bringing content down to small devices is going to
be a key issue going forward. Not only is there a need to get the content down
to small devices, but there will also be a need to make it fit many different
form factors. The further we get into 3G the bigger that variety of devices
available will be. An application should be viewable on a Palm PDA as well as a
phone with 5 rows, which is a major challenge. An important part of this is to
have content and presentation clearly separated, a feature which the relation
XML adds. WAP was built from scratch to define ways to get content formatted
for small devices with a number of different form factors.
Efficiency - As packet data becomes the preferred way of using many Mobile Internet
information sites, users are likely to pay more corresponding to the amount of
data they are transferring than the time connected. This means that everyone is
keen on having as little protocol data sent for each bit of information. The
binary coding of Wireless Session Protocol (WSP) that WAP increases the
efficiency a lot. It enables the gateway to take the well-known WSP headers and
assign them the code that both the client and the gateway knows of. This means
that the header overhead is drastically lowered.
Robustness - Wireless connections are likely to sometimes be disrupted by lack of coverage
or radio shadowing objects (like elevators). With the advent of GPRS we will
also see packet data sessions (like WAP) being interrupted by incoming
phonecalls. This is due to the use of only one transceiver in most handsets
(class B). Applications need to be robust and rebound after interruptions and
going in and out of coverage, a feature that WAP adds by letting sessions be
suspended and then later resumed.
Telephony Integration - In order to really
leverage the features that makes the Mobile Internet a very compelling market, one has to see the potential
synergies between the data part of the handset and the phone part. If I search
for a hotel and get three names, I might want to choose one of them which to
book. It would be much easier then to just select one of them on my phone's
display rather than writing down the number and dialing i. The Wireless Telephone
Application (WTA) framework adds this feature to WAP.
Finally, it is clear that
WAP is not perfect, and there will always be room for improvement. This is
however natural when a standard is developed by lots of companies over just a
few years. The advantage of this slow migration into a good applications
environment is that content for a great diversity of devices can be specified
in a unified, optimized way.
Don’t hesitate to drop me
a line with suggestions and comments. If you are in the process of developing
wireless applications, make sure to sign up as a member at the Mobile Applications Initiative.
(Membership is free and open to anyone,
not just the ones currently developing wireless applications). You can also
drop in at one of the Ericsson MAI test labs for tests in a wireless
environment and feedback on how to optimize for wireless.
About The Author: Christoffer Andersson is Senior Specialist and Manager of Special Projects for
the Ericsson. In this position he works with stratetic issues and projects in
the area of Terminals and Applications 2G/3G. Christoffer is also author of
the upcoming book ‘GPRS and 3G Wireless Applications – The Professional
Developer’s Guide’, published in May 2001 by John Wiley and Sons. Christoffer
can be reached at christoffer@wirelessdevnet.com.
The opinions expressed in this column are those of the author and not necessarily Ericsson.
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