Page 52 - DCAP512_WAP_AND_WML

WAP & WML

Notes The bridge between the wired world and wireless domain is the WAP Gateway Server.

Figure 4.2

Mobile Data Base
Devices

Data Source

Wireless
On Wire

WAP Gateway Server WAP Server

Applications

 WAP Client: End user for wireless services. The user platform includes all necessary
applications.

 WAP Gateway: Manages two-way communication between a mobile device and the wired
Internet. Translates Web Server output (HTTP) to wireless application protocols (WAP) to
send to mobile service and vice versa.
 Web Server: Standard web server, including Web Proxy. An example of this is IBM’s
Websphere Application Server.
 Data Source: This is the data repository, which could flow through other servers and
reside within one or more databases.

Mobile Device Hardware Considerations

WAP enabled devices are presently quite limited. They typically have very small screens, little
memory, limited battery power, slow rates, and awkward input keys. Two-way voice
communication is available, only the simplest of graphics input keys. Also, a programmer
cannot assume that his or her users have the most capable devices.

The World-Wide Web Model

The Internet World-Wide Web (WWW) architecture as depicted in Figure 4.3 offers a very
adaptable and efficient programming model. Applications and content are presented in standard
data formats, and are browsed by applications known as web browser. The web browser is a
network application, i.e., it sends requests for named data objects to a network server and the
server in turn responds with the data encoded using the standard formats.

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