The Vision of Ubiquitous Computing

The Vision of Ubiquitous Computing

Three essential elements make up the vision of ubiquitous computing:

   Anywhere access. Users are able to access desired services from any location, using whatever access device is convenient and appropriate for their current situa-tion, including desktop computer, landline or mobile telephone, PDA, pager, public Internet terminal, and so on.

   Parallel and complementary modes of access. Parallel modes of access give users more options regarding when, where, and how they access a given service. An example of parallel modes of access would be a map and directions service that may be accessed via a standard PC Web browser or on a Web phone while the user is traveling. In this case, both modes of access have merits and are beneficial to the user under different circumstances. On the other hand, with complementary modes of access, a service is made accessible via a variety of modes that work together to deliver the service. For example, complementary modes of access would be found in a phonebook service where users can most efficiently create and manage their contact information using a desktop PC but access this information most efficiently via a Web phone.

   Presentation-neutral application middleware. As shown in Figure 21.1, different devices use different communication infrastructures, but they all access the same application on the back-office server. It is essential, therefore, for the applications running on that server to be “presentation neutral.” Separate devices that are dedi-cated to supporting their corresponding interfaces best handle the formatting of data for presentation. XML and XSL provide excellent tools for implementing pre-sentation-neutral middleware.

   Figure 21.1 shows four separate access devices using different communication infrastruc-tures to access a common application. A desktop user may use the standard Internet tech-nologies of TCP/IP and HTTP to access the Internet directly. Alternately, a wireless PDA, two-way pager, or mobile phone user may use one of many wireless communica-tion infrastructures to access the Internet via a WAP gateway. The mobile phone might also call into a VoiceXML gateway to interact with the common application via voice, which is also possible from a landline phone.