A Wap browser provides all of the basic services of a computer based web browser but simplified to operate within the restrictions of a mobile phone, such as its smaller view screen. WAP sites are web sites written in, or dynamically converted to,WML (Wireless Markup Language) and accessed via the WAP browser.
Before the introduction of WAP, service providers had extremely limited opportunities to offer interactive data services. Interactive data applications are required to support now commonplace activities such as:
- Email by mobile phone
- Tracking of stock market prices
- Sports results
- News headlines
- Music downloads
The WAP standard[1] describes a protocol suite that allows the interoperability of WAP equipment and software with many different network technologies. The rationale for this was to build a single platform for competing network technologies such as GSM and IS-95 (also known as CDMA) networks.
- The bottom-most protocol in the suite is the WAP Datagram Protocol (WDP), which is an adaptation layer that makes every data network look a bit like UDP to the upper layers by providing unreliable transport of data with two 16-bit port numbers (origin and destination). WDP is considered by all the upper layers as one and the same protocol, which has several "technical realizations" on top of other "data bearers" such as SMS, USSD, etc. On native IP bearers such as GPRS, UMTS packet-radio service, or PPP on top of a circuit-switched data connection, WDP is in fact exactly UDP.
- WTLS provides a public-key cryptography-based security mechanism similar to TLS Its use is optional.
- WTP provides transaction support (reliable request/response) that is adapted to the wireless world. WTP supports more effectively than TCP the problem of packet loss, which is common in 2G wireless technologies in most radio conditions, but is misinterpreted by TCP as network congestion.
- Finally, WSP is best thought of on first approach as a compressed version of HTTP.
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