Workshop W2 The Web and Mobility
Mobile-transparent approach to adapt web services for WAP devices
Eija Kaasinen, VTT Information Technology, Finland
The rapid growth of Web services has led to a situation where companies and individuals rely more and more on material that is available on the Internet and intranets. An increasing number of people use Web services both at work and at home. The next step is to gain access to Web services for mobile users too. Access itself will probably be the killer application for the mobile Internet.
In our WWW-9 conference paper, "Two Approaches to Bringing Internet Services to WAP Devices" we describe our approach to mobile-transparent access to web services. We have implemented and evaluated an HTML/WML conversion proxy server with which current Internet services can be converted transparently and in real time suitable for mobile users with WAP devices. Through the proxy server, the users can in principle access exactly the same Web services as from their desktops. 
Figure: Mobile-transparent approach to service design makes it possible to create generic services both for mobile and fixed terminals
Our experience shows that it is possible to make Web services that adapt to different terminals, both desktop and mobile, without diminishing the site's usability or visual appeal. To support the conversion, the Web page designer has to follow certain guidelines. In principle, these guidelines already exist as W3C Mobile Access  and Accessibility Guidelines . The guidelines do not restrict the visual design of the service but rather recommend alternative formats and proper use of meta data. 
In the future there will be a need for both mobile-transparent and mobile-aware services. Mobile-aware services will be specially designed for mobile users. Often these services will be designed to be used at a certain place, e.g. conference information system, or the services utilize the location information of the user, e.g. tourist information in a city. The mobile-aware service may be accompanied by a web service but both services have their own functions.
Most web services are, however, such that people need to access them any time and anywhere. Users want to use the same services with different devices depending on their current context of use. The services have to adapt their contents and presentation according to the device and network characteristics and user preferences. It is beneficial to maintain the look and feel of the service as much as possible because familiarity improves usability.
Most of the currently available WAP services are not generic but they have been tailored to specific WAP devices. Even if the service is generic, ít has been designed according to the minimum client device. Then the service cannot utilize the more advanced features of other devices. The selection of WAP devices is expected to range from mobile phones to palmtop computers. As more devices will be available on the market, it will require more and more efforts to maintain device-specific services. Adapting the contents to different devices, networks and user preferences will be a big challenge for service designers.
User Agent Profile (UAProf) specification, released by WAP Forum in November 1999, provides the technical framework for service adaptation. The profile includes a lot of attributes, classified as hardware, software, network, user agent and WAP characteristics . Utilizing the profile requires quite a lot of work in the service design.
People consider mobile devices very personal and that is why it is natural to require personalized services and information on the device. Personalization also improves the usability of services by filtering out unnecessary information. In this way it is easier for to the user to find the key information and functions. The problem with
We are currently redesigning our conversion proxy such that in addition to the conversion, it will also automatically adapt the service according to the current context of use. The adaptation will be made according to the User Agent Profile of the client device. In this way mobile-transparent services could be transparent also to the user device, network and user preferences. Utilizing the conversion proxy may save a lot of development and maintenance costs from the content provider.
We have quite many research questions ahead. WAP UAProf defines a collection of attributes of the user agent profile. Is it possible to define general rules how to adapt any service according to the User Agent Profile? Where do we need mobile-aware services and where is it possible to make mobile-transparent, adaptive services? Could the conversion proxy also participate in the personalization of the contents?
HTML 4.0 Guidelines for Mobile Access. W3C Note. 15 March 1999. http://www.w3.org/
Kaasinen, E., Aaltonen, M., Kolari, J., Melakoski, S. and Laakko, T. Two Approaches to Bringing Internet Services to WAP Devices. WWW-9 conference. Amsterdam. May 2000.
Web Content Accessibility Guidelines 1.0. W3C Recommendation. 5 May 1999. http://www.w3.org/.
Wireless Application Group. User Agent Profile Specification. Version 10-November-1999. Available at http://www.wapforum.org/what/technical.htm