Wireless Application Protocol
The Wireless Application Protocol (WAP ) refers to a collection of techniques and protocols, whose goal is to make Internet content for the slower transmission rate and longer response times in mobile communications and for the small screens of mobile phones available. Various WAP implementations were thus in direct competition with the i- mode service. Because of its complexity, faster connections and HTML -enabled mobile devices, WAP is largely obsolete today.
Technique of WAP
The primary task of WAP is to reduce due to the small display capacity and computing power of WAP clients, the amount of data to be transmitted and at the same time in the coding of this website, the open structure and readability of a markup language (English markup language) to maintain. These two requirements are initially in conflict:
- A human-readable markup language contains a lot of data for readability (comments, commands in readable form ), but not necessary for content description.
- Coding binary shape allows a very compact implementation, but has neither an open structure, nor is it read.
The solution of the problem is that WAP although the open form of a markup language ( WAP this is the Wireless Markup Language, WML ) is maintained, it is not transferred as text but in compiled form to the WAP client. For this purpose, the communication between the WAP client and the Web server through a proxy, the so-called WAP gateway. This translates the binary arriving from WAP client requests in clear text to the web server. The responses from the server are in the WAP gateway compiles the MIME type WMLC Wireless Markup Language ( Compiled ) transmitted to the client. For this purpose, the gate-way tasks (such as syntactic analysis of WML pages ) that executes in the Web browser.
The communication between the server and the WAP gateway uses the established HTTP protocol on the Web. The communication between the gateway and WAP client is done ( to WAP 1.2 ) via WSP. In the use of the carrier on the radio link WAP is flexible, it is possible, for example Circuit Switched Data (CSD ), High Speed Circuit Switched Data ( HSCSD), General Packet Radio Service (GPRS), as well as Universal Mobile Telecommunications System (UMTS ) and high Speed Downlink Packet Access ( HSDPA). The use of the GSM - specific USSD bearer service is also possible.
WAP -based applications
WAP is used as a basic technology for MMS. Both the transmitting and the receiving of a multimedia message based on the WAP. The information that a multimedia message is ready for downloading, is transmitted as a WAP push to the mobile telephone.
The WAP standard (from WAP 1.2 ) supports a push service, which allows you to send messages without including a URI request to the WAP client. For the user of the WAP Push service of a text or multimedia message looks similar. Technically hidden behind a signaling via SMS or - with GPRS or UMTS - even by Service Indication ( WAP -167 - ServiceInd ) (SI ) or Service Loading ( WAP -168 - Service Load) (SL).
WAP 1.0 to 1.2
The WAP Forum WAP 1.0 standard, adopted in 1997. WAP 1.0 is based on the Handheld Device Markup Language ( HDML ), by the company Unwired Planet (now Openwave ) was developed. However, the standard was not mature, and there was a lack of appropriate browser software and WAP - enabled devices. Thus, the standard could not prevail commercially and remained practically without any meaning.
1999, the 1.1 standard was published, in particular took over XHTML conventions. This standard was not compatible with WAP 1.0. With WAP 1.1, the default was able to prevail decisively on the market for terminals, so that soon every mobile phone is equipped with a WAP browser. The presented end of 1999, WAP 1.2 is primarily an improvement of WAP 1.1 represents the most important extensions are the push service and so-called user agent profiles for WAP browsers, which allow transmitted WAP pages in their formatting comfortable to adjust the browser software specifically used.
Internet access via WAP 1.x is usually charged separately by the mobile operators and not counted as direct internet access (web ). The traffic runs over own WAP APN.
WAP 2.0
In the specification of WAP 2.0 one has to Mobile specifics largely dispensed with and replaced the original WAP protocols WSP, WTP and WTLS through HTTP and SSL. In order for the transition to the Internet is much easier. WAP 2.0 is also wrestling with CSD and GPRS with speed problems. About WAP 2.0 all normal web pages are accessible in the rule; due to the low speed of GPRS many, however, are reasonably used only with EDGE or UMTS.
With WAP 2.0 and the proxy concept has been softened. The standard now provides for the possibility that the client, bypassing the gateway communicates directly with the web server. However, it can also be used by the mobile operators offered proxy. Although the independence of a proxy eliminates the dependence on the proper functioning of the WAP gateway, but has the disadvantage that it is already WAP 2.0 clients are no longer support the WSP. These can then no longer use the available WAP proxy.
The use of the internet via WAP 2.0 will be charged by the mobile providers usually as a direct Internet access. With GPRS or UMTS then usually fall for each page costs depending on the exact volume of data, while it is common for WAP 1.x, only per page (ie, per each ticked link) settle. In some tariffs by the cost per page view for data- intensive HTML pages can be much higher than that of WAP 1.x; very small sites can also be effective against it.
Write Some mobile phone manufacturers in the information on their devices that it would WAP 2.0 -enabled devices, but it do not mean the transfer of technology, but just the fact that the devices can also XHTML pages show instead of only the WML pages. In the WAP settings, however, the WAP 1.x settings are still entered.
Risks
About WAP can handle payment services. Since WAP sites are not distinguishable from other Internet sites usually can be done so unintentionally and unexpectedly claiming for paid services associated with the caller's ID to the service provider or a switched between collection companies.
Similar services
A similar service is i-mode. While WAP is a standardized technology, i-mode is a proprietary development by NTT Docomo.
Dissemination and use
As mobile customers after the introduction of WAP technology first could hardly rely on faster data transfer standards such as GPRS or HSCSD and Settlement in the traffic normally carried out on a time basis, declared scoffers the abbreviation jokingly with " Wait And Pay ", English for " wait and pay ." While the initial speed problems now no longer exist, WAP remains in spite of imported flat rates at normal charge per click or per packet compared to the generally significantly lower internet charges on mobile access to the content offered is prohibitively expensive. This is also a reason why the WAP technology has developed only very limited, despite some useful deals.