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WAP Service Developer's Guide for Nokia Series 40
Version 1.0
Copyright © 2002. Nokia Corporation. All rights reserved.
6
2 GENERAL USABILITY ISSUES – GUIDELINES FOR DESIGN
Nokia phones are renowned for their simple-to-use and intuitive user interface. In order to
create a service that will be perceived as usable and easy to understand, Nokia Mobile
Phones provides some general guidelines to help service providers develop their applications.
2.1 Mobile applications for mobile use
When deciding what information to include in the different applications on a mobile
terminal, think about what information might be relevant in the situations where the mobile
phone will be used. Mobile phone is primarily used when there is no access to the Internet
with a PC. We believe that users of mobile applications will be interested primarily in brief
and quick information. For instance, quick access to flight schedules from the mobile phone
might be relevant for users. Similarly, several short newsflashes are more relevant than
longer news articles. Quick access to weather information may also be of use in the mobile
situation to quickly check the temperature at the destination of the traveler. However, it is
less likely that users will surf using the application on the mobile terminal, but will prefer to
surf the Internet on a PC from the office or home.
2.2 Validate your WML
There are several XML validators available that validate your documents against WML
Document Type Definition. It is recommended that authors validate their WAP pages,
because invalid WML is always treated as an error and is discarded by the WAP gateway
(that is, it is not shown to the user).
Several XML validators can be found at http://www.wapdevelopers.org
2.3 GPRS usability
GPRS features efficient use of resources, instant access, fast delivery of information and
innovative charging models. Together, WAP and GPRS not only improve the user experience
of existing applications but also enable new services.
2.3.1 Not necessary for developers to make changes
GPRS enhances the end user experience of the mobile services currently being delivered over
circuit switched data (CSD). Since the WAP standard was designed to allow content to be
delivered over any bearer service, it is not necessary for developers to make changes to their
WAP-compliant services or applications, even when delivery of the services is enabled over
GPRS, 3G or any other type of network.
2.3.2 Cache utilization
It is recommended to use HTTP proxy to cache WML content whenever the content is
accessed through the Internet. The proxy should be placed close to the WAP gateway to
minimise the distance for data transfer between the two components. The home page (first
page) might alternatively be kept on a local server, close to the WAP gateway.
Most clients have a cache and using it is an important way to provide fast user experience.