Lectured By: Vivek Dimri Assistant Professor, CSE Dept. SET, Sharda University, Gr. Noida

WAP (Wireless Application Protocol) The Wireless Application Protocol or WAP is an open, global standard for mobile communication. WAP allows mobile users to access and interact with different informational services. The approach used is to utilize as few resources as possible on the handheld device and compensate for the constraints of the device by enriching the functionality of the network.

WAP (Wireless Application Protocol) Wireless Application Protocol (WAP) is simply a protocol- a standardized way that a mobile phone talks to a server installed in the mobile phone network. It is an open specification that offers a standard method to access Internet based content and services from wireless devices such as mobile phones and PDAs.

WAP (Wireless Application Protocol) WAP defines a communication protocol as well as an application environment. In essence, it is a standardized technology for cross- platform, distributed computing. Sound similar to the World Wide Web. WAP is very similar to the combination of HTML and HTTP except that it adds in following important features: Optimization for low-bandwidth Low-memory Low-display capability environments. These types of environments include PDAs, wireless phones, pagers, and virtually any other communications device.

How Does WAP Works?? A WAP request is routed through a WAP gateway which acts as an intermediary between the “bearer” used by the client (GSM, CDMA, TDMA, etc.) and the computing network that the WAP gateway resides on (TCP/IP in most cases). There is a gateway server active between the user agent and the content server.

How Does WAP Works??

The primary job of the gateway server is: First it must translate WAP protocols sent by the user agent into HTTP for communication with the content server. Secondly it must receive the requested content from the content server, encode the response into the appropriate WAP protocol and send it to the user agent. So, the communication between the user agent and the WAP gateway server is done with WAP protocols. The communication between the WAP gateway and the content server is done with HTTP.

How Does WAP Works??

WAP Protocol Stack WAP is designed in a layered fashion in order to be extensible, flexible, and scalable. With the Open System Interconnection model (OSI model) in mind, the WAP-stack basically is divided into five layers. These layers consist (from top to bottom) of: Wireless Application Environment (WAE) Wireless Session Protocol (WSP) Wireless Transaction Protocol (WTP) Wireless Transport Layer Security (WTLS) Wireless Datagram Protocol (WDP) Bearers (GSM, IS-136, CDMA, GPRS, CDPD, etc.)

WAP Protocol Stack

Each layer of the WAP protocol stack specifies a well- defined interface to the layer above, meaning that a certain layer makes lower layers invisible to the layer above. The layered architecture allows other applications and services to utilize the features provided by the WAP- stack as well. This makes it possible to use the WAP-stack for services and applications that currently are not specified by WAP.

WAP Protocol Stack Application Layer: Wireless Application Environment (WAE): The uppermost layer in the WAP stack. The Wireless Application Environment (WAE) provides an environment that enables a wide range of applications to be used on wireless devices. Session Layer: Wireless Session Protocol (WSP): WSP is the interface between WAE and the rest of the protocol stack. The main functionality of the connection mode of WSP is to set up a session between a client and the WAP Gateway/Proxy. This session handles capability negotiation at session establishment and communication interrupts such as change of bearer.

WAP Protocol Stack Transaction Layer Wireless Transaction Protocol (WTP): WTP is responsible for control of transmitted and received messages. It provides a reliable communication where messages are uniquely identified so as not to be accepted twice and may be retransmitted to the peer if lost in transmission. There is no connection between communications as every communication sequence is only alive during the exchange of an individual message set.

WAP Protocol Stack Security Layer Wireless Transport Layer Security (WTLS): The purpose of WTLS is to provide transport layer security between a WAP client and the WAP Gateway/Proxy. WTLS is based on Transport Layer Security (TLS) 1.0 but optimized for narrowband communication channels. Transport Layer Wireless Datagram Protocol (WDP): The base of the WAP protocol stack is a datagram layer, WDP, offering a consistent interface to the upper layers of the stack. If necessary WDP can also be extended with functionality for segmenting and reassembling datagram’s that are too big for the underlying bearer. It is also possible to extend WDP with an optional protocol for error reporting called Wireless Control Message Protocol (WCMP).

WAP Layer’s Summery WAE (Wireless Application Environment) Architecture: application model, browser, gateway, server WML: XML-Syntax, based on card stacks, variables, WTA: telephone services, such as call control, phone book etc WSP (Wireless Session Protocol) Provides HTTP 1.1 functionality Supports session management, security, etc. WTP (Wireless Transaction Protocol) Provides reliable message transfer mechanisms Based on ideas from TCP WTLS (Wireless Transport Layer Security) Provides data integrity, privacy, authentication functions Based on ideas from TLS/SSL WDP (Wireless Datagram Protocol) Provides transport layer functions Based on ideas from UDP