Wireless communication - WAP
WAP stands for Wireless Application Protocol. WAP represents a suite of protocols rather than a single protocol. WAP aims to integrate a simple lightweight browser also known as a micro-browser into portable devices, thus requiring minimal amounts of resources such as memory and CPU > on these devices.
WAP attempts to compensate for the shortcomings of portable wireless devices and wireless linkage by incorporating more intelligence into network nodes such as routers, web servers, and BS .
The main objectives of the WAP protocol suite are as follows.
- Independence from wireless network standards
- Interoperability between service providers
- Overcome gaps in wireless support
- Overcome the disadvantages of portable devicess
- Increase efficiency and reliability
- Provide security, scalability and scalability
The WAP model
WAP takes a client-server approach. It specifies a proxy server that acts as an interface between the wireless domain and the main wired network. This proxy server, also known as a WAP gateway , is responsible for a wide variety of functions such as protocol translation and optimization of data transfer over the wireless medium.
The parts of the wireless network are made up of -
- Content provider (Application or origin server)
- Mobile device (WAP client)
- WAP gateway
- WAP proxy
The WAP architecture has been designed to closely follow the Web. The only difference is that the presence of the WAP gateway translates between HTTP and WAP.
The three sections to mention concerning the clientt WAP are the WAE user agent, the WTA user agent, and the WAP stack.
WAE user agent - The user agent of the wireless application environment is the browser which gives the content to display.
WTA User Agent - The Wireless Telephony Application Agent receives compiled WTA files from the WTA server and executes them.
WAP stack - The WAP stack allows the phone to connect to the WAP gateway using WAP protocols.
The element of the network where information applications (Web, WAP) reside is the WAP proxy , the WAP gateway or the WAP server -
Proxy - It 's an intermediate element acting both as a as a client and as a server in the network, it is located between the client and the server. The client sends him requests and he retrieves andcaches the necessary information by contacting the origin server.
Gateway - This is an intermediary element generally used to connect two different types of networks.
The WAP gateway is basically a software placed between a network supporting the WAP and IP packet network such as the Internet.
The WAP protocol stack
The WAP protocol stack is shown in the following figure -
The Application Layer provides an application environment intended for development and Running portable applications and services, WAE consists of two different user agents located on the client side.
The WAE user agent consists of a browser and a Text message editor as well as WTA user agent.
Session layer provides me with thods for organized exchange of ent contentre the customer / service applications.
WAP contains the following components -
Connection oriented session services - They work via WTP .
Connectionless session services - They work directly through WDP.
Session Services - These features help to establish a connection between a client and a server using primitive messages.
Primitive messages are defined as messages that the client sends to the server to request a service installation. The client sends request primitives and receives a confirm primitive, and the server can send response primitives and receive indication primitives.
The Connectionless Session Service provides only unconfirmed service. To start the session, the client invokes WSP primitives which provide certain parameters, such as the addressse from the server, the client address and the client headers. In some ways, WSP is essentially a binary form of HTTP.
Provides various methods for performing transactions with varying degrees of reliability.
Optional layer that provides, when authentication, privacy and secure connection are present, between applications. It is based on SSL (Secure Socket Layer) . It provides services that guarantee confidentiality, server authentication, client authentication and data integrity.
A standard SSL session is opened between the web server and the WAP gateway, and the WTLS session is initiated between the gateway and the mobile device . The encrypted content is sent through this connection from the server to the gateway, which translates it and sends it to the mobile phone. The transaction between SSL and WTLS takes place in the memory of the WAP gateway.
This is the bottom layer, connected to the support service offered by the operator. Bearer services are the communication between the mobile phone and the base stations. They include SMS, CSD, USSD, GSM, GPRS, DECT, CDMA, FDMA, and TDMA .
The physical layer prepares the data to be sent from the mobile device on the air services and sends the data using the support service implemented in the network in which the device is operating. WDP interfaces with transaction request-response oriented protocol instead of the three-way connection mechanism.