In general, the structure of the wireless application protocol (WAP) architecture is layered, with each component stacked up on top of the other. This architecture is sometimes referred to as “WAP Stack.” The layered structure allows the WAP to accommodate other components if needed, making it adaptable and expandable. The three primary layers in the WAP architecture consist of the Wireless Datagram Protocol (WDP), the Wireless Transaction Protocol (WTP), and the Wireless Session Protocol (WSP). Other layers such as the Wireless Transport Layer Security (WTLS) and the Wireless Application Environment (WAE) are also often included in the stack and have important functions.
Sitting at the very bottom of the WAP architecture is the network carrier method, or the medium in which information is sent, such as short message service (SMS) for text messaging, or general packet radio service (GPRS) for mobile Internet connection. Just above the carrier is the WDP, which becomes the medium between the carrier and the layers above it. It makes sure that the WAP is synced properly to the carrier method so the connection is stable, consistent, and continuous.
Just above the WDP is the WTLS. As the name suggests, this layer in the WAP architecture ensures that data is secured and restricted from a third party “eavesdropper.” This means that the WTLS usually embeds an encryption on the messages passed from one network to the other, and checks the message and the sender’s network for authentication. The WTLS also ensures that the message maintains its integrity and experiences no alteration when it is being received.
The WTP, on top of the WTLS, manages the transfer of data. One can think of the WTP as a traffic enforcer who allows the messages to be sent and received. For example, the WTP does not allow a mobile phone to send messages when there is no signal, nor does it allow another mobile phone to receive messages when it is turned off. This layer is also responsible for organizing the messages, which is why data is usually sent according to the time and date of transaction.
After the WTP comes the WSP, which determines whether dual exchange of information is requested during data transfer, or just a one-way exchange is needed. When a two-way exchange is involved, such as in chat rooms and video conferencing, the WSP redirects the data to the WSP to manage the data flow. If a one-way transaction is carried out, such as in video streaming, the WSP assigns the data to the WDP to make sure the data packets are continuously being sent until the data is complete.
The topmost layer of the WAP architecture is the WAE, which provides a venue for programmers and other users to create and edit the content and the way an application works. This layer can contain HyperText Markup Language (HTML) codes for web pages and the URL that acts as the address to a website. Among the layers in the WAP architecture, the WAE is probably the most accessible to any user who wants to customize his website, replace the background of the pages, change the color of the texts, and even program his own game and tools.