What is Wireless Application Protocol (WAP)?

Wireless Application Protocol (WAP) is a technical standard and a set of communication protocols that enable the delivery of internet-based content and services to mobile devices, such as cell phones and personal digital assistants (PDAs), over wireless networks. It was designed to bring web-like functionality and services to mobile devices, allowing users to access information, browse websites, and interact with online services from their handheld devices.

Dissecting Wireless Application Protocol (WAP)

WAP, a collaborative effort among companies like Nokia, Ericsson, Motorola, and Unwired Planet (later known as Phone.com and eventually Openwave), emerged in the late 1990s after the formation of the WAP Forum in 1997. This consortium played a pivotal role in shaping the WAP standard.

The primary motivation for creating WAP was to provide mobile devices, including cell phones and PDAs, access to internet-based content and services. At the time, these devices faced limitations in processing power, memory, and screen size, necessitating a standardized protocol and framework to make web content accessible.

WAP’s Architecture

The architecture of the Wireless Application Protocol (WAP) is designed to facilitate internet access over wireless networks. This architecture addresses the challenges posed by the limited bandwidth, processing power, and display capabilities of early mobile devices.

1. WAP Client: This is typically a mobile device, such as a cell phone or a PDA, equipped with a WAP browser. The WAP browser is responsible for initiating requests to the WAP gateway and rendering content received in response. It primarily uses Wireless Markup Language (WML) for content display.
2. Wireless Markup Language (WML): WML is a lightweight markup language designed for creating web pages that can be displayed on mobile devices. It is optimized for small screens and low bandwidth conditions, similar to how HTML is used for standard web pages.
3. WAP Gateway (or WAP Proxy): The WAP gateway serves as an intermediary between the WAP client and the internet. It translates WAP requests into standard web protocols (like HTTP) and vice versa. This translation includes converting WML content into HTML for web servers and then back into WML or other suitable formats for the mobile client. The gateway also often includes a scripting engine for running Wireless Markup Language Script (WMLScript), which is a lightweight scripting language for client-side scripting in WAP.
4. Wireless Session Protocol (WSP): WSP is a protocol used for session management and offers both connection-oriented and connectionless services to the upper layers. It optimizes the transfer of data between the client and server by providing a fast connection setup and efficient data transfer mechanisms.
5. Wireless Transport Layer Security (WTLS): WTLS is the security layer in the WAP architecture, providing privacy, data integrity, and authentication for WAP services. It is analogous to the TLS/SSL protocols used in traditional internet communications.
6. Wireless Datagram Protocol (WDP): WDP acts as a universal data datagram service that is adapted to the specific features of various wireless networks. It offers a consistent data format to the higher layers of the WAP stack, irrespective of the underlying network.
7. Wireless Telephony Application Interface (WTAI): WTAI provides interfaces to telephony services, such as making calls, sending SMS messages, and phonebook access. This allows WAP applications to integrate closely with the mobile phone's telephony functions.

How WAP Works

To deliver internet content to mobile devices, WAP utilizes a series of steps and components that collaborate effectively. 

1. User Initiates a Request: The process starts when a user on a WAP-enabled mobile device opens their WAP browser and requests a web page. This is similar to how one would use a web browser on a computer, but the mobile browser is typically designed to handle WAP standards and formats.
2. Request Sent to WAP Gateway: The request from the mobile device is sent to a WAP gateway. This gateway plays a crucial role as it acts as an intermediary between the mobile network and the internet.
3. Conversion of WAP Request: The WAP gateway converts the WAP request, which is typically in a binary format suitable for wireless transmission, into a standard HTTP request that can be understood by web servers on the internet. This step may also involve translating content requests from Wireless Markup Language (WML) into standard web languages like HTML.
4. Fetching the Content: The HTTP request is sent to the appropriate web server over the internet. The server processes this request like any other web request, generating a response with the requested content.
5. Content Conversion at WAP Gateway: Once the web server responds, the WAP gateway receives the data. It then converts this data (which might be in HTML, JavaScript, or other web technologies) back into a WAP-compatible format, typically WML. This step may also involve compressing the data to make it suitable for transmission over the limited bandwidth available on mobile networks.
6. Delivery to Mobile Device: The converted content is sent back to the user's mobile device over the wireless network. This data transmission typically occurs over a protocol like Wireless Datagram Protocol (WDP), which is designed to be compatible with various wireless network standards.
7. Rendering on Mobile Device: The mobile device receives the WAP content and the WAP browser renders it on the screen. Given the constraints of early mobile devices, WML is designed to be simple and efficient for small screens, providing a basic but functional user interface.
8. User Interaction and Further Requests: Users can interact with the content, click on links, or submit forms. These actions initiate new WAP requests, repeating the cycle as described above.