What is WAP - 2

A free article on Mobile Phones

By: Ivan Komarov

TECHNICAL INFORMATION

Developers of WAP tried to use existing World Wide Web (WWW) technologies as much as possible. Therefore, WAP architecture is very similar to WWW architecture. WAP uses the same resource addressing as WWW, the same names for data types. There are also analogues of HTML and JavaScript in WAP.

A mobile device with a build-in browser is a client. It sends requests to a WAP gateway which receives responses from a server and sends them back to the client. An ordinary web server can function as the server in the WAP architecture. Such architecture allows the use of existing and time-proof technologies such as PHP, ASP, CGI and so on.

WAP gateway translates requests from the WAP to WWW protocol and vice versa, also transcoding data to optimize traffic. {1}

WAP is also an application environment and it can be built on any operating system, including PalmOS, EPOC, Windows CE, FLEXOS, OS/9, and Java OS. Products that support WAP include digital wireless devices such as mobile phones, pagers, two-way radios, smart phones, and communicators. WAP is designed to work with the most wireless networks, such as GSM, DECT, CDMA, CDPD, PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA,
Data TAC, and Mobitex. {2}

Comment: A WAP gateway from the technical viewpoint is used to translate protocols. However, it can also be used to append additional information (subscriber’s number, location, information about the phone model) to a user’s request.

WAP 1.0 AND WAP 2.0

The mobile web utilizes the Wireless Application Protocol (WAP). There are two main types of WAP sites: WAP 1.0, which uses Wireless Markup Language (WML), and WAP 2.0, which is based on xHTML. WAP 2.0 is increasingly the platform of choice, because it allows for a much richer experience than WAP 1.0. Many manufacturers and carriers are moving away from WAP 1.0. {3}

WAP 2.0 is a re-engineering of WAP using a cut-down version of XHTML with end-to-end HTTP (i.e., dropping the gateway and custom protocol suite used to communicate with it). A WAP gateway can be used in conjunction with WAP 2.0; however, in this scenario, it is used as a standard proxy server. The WAP gateway's role would then shift from one of translation to adding additional information to each request.

Comment: In other words, the main role of the gateway shifts from translating the protocols to adding additional information to requests.

XHTML Mobile Profile (XHTML MP), the markup language defined in WAP 2.0, is made to work in mobile devices. It is a subset of XHTML and a superset of XHTML Basic. A version of cascading style sheets (CSS) called WAP CSS is supported by XHTML MP. {1}

Comment: WAP 2.0 is, most likely, a response to an increase in transmission speeds in wireless networks and also a direct consequence of increased sophistication of devices.

WAP PUSH

WAP Push has been incorporated into the specification to allow WAP content to be pushed to the mobile handset with minimum user intervention. A WAP Push is basically a specially encoded message which includes a link to a WAP address. WAP Push may be delivered by GPRS or SMS (as it is specified on top of WDP and can be delivered on top of any WDP-supported bearer).

In most GSM networks, however, WAP Push messages must be delivered only on top of SMS messages. On receiving a WAP Push, a WAP 1.2 or later enabled handset will automatically give the user the option to access the WAP content. This is also known as WAP Push SI (Service Indication).
The network entity that processes WAP Pushes and delivers them over an IP or SMS Bearer is known as a Push Proxy Gateway. {1}

Comment: In services that we offer our users, WAP is used in exactly this way; one gets an SMS message with a WAP link, clicking on which initiates download of requested content. The same way is used to deliver WAP addresses in a more general context. Instead of tapping an address manually, a user can save the SMSed link in bookmarks.