WML provides the basic means for document formatting and user interaction, but presupposes little about how they are actually implemented. Each client device implements the interactions in its own way, depending on the device type and the WML browser software (WAP Forum 1999).
The first WAP-compliant devices have been mobile phones, but in the future WAP devices will vary a lot in size, input/output facilities, accepted content types, network connections etc.
In our project, parallel to the ongoing international specification work of WAP, we have studied in practice how the future WAP services can be designed and implemented. On the one hand, we are studying how to build mobile aware services using WML. As a case study we have developed a business card search service. On the other hand, we have developed a WAP Proxy server, which is able to convert HTML pages automatically to WML, thus providing mobile transparent services.
Mobile users require easy and efficient access to WAP services. Terminals may have small screen sizes, limited memory capacities, restricted input mechanisms and slow network connections. The users want the services to be able to adapt to various terminal devices in the best possible way ( Clarke et al. 1997).
The service providers have to decide if they want to make a specific WAP application or to rely just on HTML/WML conversion. The conversion approach may be sufficient when mobile users are not an essential user group of the service or when the structure of the service is very straightforward.
The technical support group of our project includes not only designers and usability experts but also members from the telecommunications industry. In the support group we have a device manufacturer (Ericsson), whose interest is to assure that their future WAP devices will provide a good platform for WAP services. We also have a network operator (Radiolinja), who will provide their own and third party WAP services to their mobile clients. The third member is a software company (Teamware), which is interested in studying how to design and implement WAP-compliant services for their clients in the future.
We have adopted an iterative human-centred design approach based on the draft ISO standard ISO/DIS 13407 (ISO/DIS 1997). Our usability framework includes effectiveness, efficiency and satisfaction as defined in draft ISO standard ISO/FDIS 9241-11 (ISO/FDIS 1997). In our project we will evaluate both use-