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2 Guidelines for Design
The Nokia Series 30 UI is designed to be easy to use and intuitive. The following section offers general
guidelines to help developers create browsing applications that will be perceived as usable and easy
to understand.
2.1 Applications for Mobile Use
When deciding what information to include in various applications on a mobile terminal, developers
should consider the types of situations where the mobile phone will be used. The content of the
service should fulfill the needs of the target user group and be optimized for the most common tasks.
Because of the mobility of the small display, the user might primarily use the mobile phone when
there is no PC access to the Internet, and for quick information. Examples might include speedy access
to flight schedules, short news flashes, and access to weather information or checking the
temperature at a traveler’s destination. It is less likely that users will use their mobile phones to surf.
2.2 Validating WML
There are several XML validators available that validate 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 discarded (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 enables efficient use of resources, instant access, fast delivery of information, and innovative
charging models.
2.3.1 No changes required by developers
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 services or applications. This is true even
when delivery of the services is enabled over GPRS, 3G, or any other networks.
2.3.2 Cache utilization
Developers should 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 minimize the distance for data
transfer between the two components. The home page (first page) can alternatively be kept on a local
server, close to the WAP gateway.
Most clients have a cache; using it is a good way to improve the user's experience. Cache headers
should be sent with documents to ensure that pages are cached on the client if possible. Content
developers should not assume that pages are cached by default.
2.3.3 Usability tips
Round trips in the network add a minimum two-second delay to the response time. Therefore the
number of round trips should be minimized. The response time of a first page has a strong impact on
the user experience, so it is worth optimizing.
WAP Service Developer's Guide for Nokia Series 30 Phones with WML Browser
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