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WAP Wireless Application Protocol (WAP) was originally founded by Nokia, Ericsson, Motorola and Unwired Planet in 1997. It is a set of standards that have been agreed upon to define how a mobile device (e.g. phone, PDA etc) talks to a server installed in the mobile operators network. This in turn enables mobile devices to access services on the Internet. The WAP Gateway infrastructure within the Orange network enables subscribers with a suitable WAP capable device to access to a wide variety of information such as news, weather and sports results. It also enables access to various other high value products and services such as games, multimedia, application downloads and location based services.
WAP is a protocol that is bearer independent and so it is possible to run WAP over existing infrastructure such as Circuit Switched Data (CSD), Short Message Service (SMS) and General Packet Radio Service (GPRS). WAP version 2.0 is an enabler for new media features such as streaming, or downloading large multimedia content (such as music and video). The WAP 2.0 protocol suite provides Internet-based data services on mobile phones and completes the migration to XHTML (Extensible Hypertext Markup Language) and TCP (Transmission Control Protocol) as the foundation of the technology – making it easier for developers to write applications. With XHTML-MP capable devices, users will have a much richer experience with applications that make use of the coloured graphics and text capabilities. Orange currently offer CSD and GPRS bearer access but WAP's versatility is such that any mobile network standard is acceptable (such as Code Division Multiple Access (CDMA) or even Universal Mobile Telephone System (UMTS). The diagram below shows the protocol stacks involved when a WAP 1.x device connects to an Internet
To increase security, the terminal may use the security layer (WTLS) to authenticate the WAP Gateway and encrypt the messages while transferred over the air. In addition, the terminal may require the WAP Gateway to establish a secure path from the WAP Gateway to the Web server using SSL/TLS - in this case the WAP Gateway decrypts and encrypts the messages before transferring them between the two transmission legs. WAP Push is a method of sending personalised, interactive messaging or advertising to a WAP Push enabled device. There are two efficient means of proactively sending ("pushing") content to a mobile device: by the Short Message Service (SMS) or by the mobile device maintaining a permanent GPRS (mobile originated) session with the content server. There are two types of WAP Push message – Service Loading (SL) and Service Indication (SI), and the experience encountered when receiving a WAP Push message varies considerably for each type, depending on the mobile device:
SL Push message functionality is technically very similar to MMS – the first the user may know is after the content has been downloaded.
The following diagram shows the transaction flow of a SI Push message.
WAP version 2.0 is an enabler for new media features such as streaming, or downloading large multimedia content (such as music and video). The WAP 2.0 protocol suite provides Internet-based data services on mobile phones and completes the migration to XHTML (Extensible Hypertext Markup Language) and TCP (Transmission Control Protocol) as the foundation of the technology – making it easier for developers to write applications. With XHTML-MP capable devices, users will have a much richer experience with applications that make use of the coloured graphics and text capabilities. The diagram below shows a WAP 2.0 device accesses a web server in the Internet.
The WAP Gateway acts as the transport protocol converter as in the WAP 1.x example. However, it converts the wireless optimised HTTP/TCP to the regular HTTP/TCP protocol supported by web servers. WAP 2.0 also brings greater security, which resolves the well-documented WAP 1.x security hole. The diagram below shows the WAP 1.x security model.
Since the protocols being used between the WAP device and WAP gateway (WTLS), and between the WAP gateway and the Web server (TLS/SSL) are different, the data is unencrypted within the gateway. The diagram below illustrates the primary elements involved when a WAP capable device communicates with a Web server – showing the architectural overview of WAP, the primary elements involved, and the protocols used.
Starting from the mobile device in the diagram above, the WAP capable device attaches to the mobile network. This can be via various methods - probably by either CSD or GPRS. Once a connection is made, the WAP device will submit the request for the URL to the WAP gateway using WAP protocols (WSP/WTP or HTTP if it is a WAP 2.0 device). The WAP gateway in turn requests the specified URL via standard Internet protocols (HTTP/HTTPS). Once the Web server returns the content to the WAP gateway, the WAP gateway can perform various optimisation or conversion of the content. If the content conforms to WAP 1.x specifications and is WML form (the human readable type), the WAP gateway compiles the WML into tokenised WML, or WMLC. This is where the code is "compressed" into binary data (the machine readable type), to reduce over the air bandwidth usage. This tokenised WML is then passed onto the WAP device (if the content from the webserver is already in tokenised WML format, the WAP gateway skips this operation). Once the WMLC is received by the WAP device, the WAP browser will render the content on the WAP device display for the user to view |
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