Wireless Application Protocol
The Wireless Application Protocol ( WAP ) refers to a collection of technologies and protocols , the aim of which is to make Internet content available for the slower transmission rate and longer response times in mobile communications and for the small displays of mobile phones . Various WAP implementations were thus in direct competition with the i-mode service. WAP became somewhat widespread mainly in the 2000s. Due to its complexity, larger displays in smartphones , now faster connections and HTML -capable mobile devices, it is largely outdated today.
Technology from WAP
The primary task for WAP is because of the small display capacity and computing power of WAP clients to reduce the amount of data to be transmitted at the same time in the coding of the internet content of the open structure and readability of a mark-up language (English. Markup language ) to maintain. These two requirements initially contradict each other:
- A legible markup language contains a lot of data that is necessary for legibility (comments, commands in legible form), but not for content description.
- Coding in binary form allows a very compact implementation, but has neither an open structure nor is it readable.
The solution to the problem is that in WAP, although the open form of a markup language (in WAP this is the Wireless Markup Language , WML) is retained, this is not transmitted as text, but in compiled form to the WAP client. To this end, communication between the WAP client and the web server takes place via a proxy , the so-called WAP gateway . This translates the incoming binary requests from the WAP client into plain text to the web server . The responses from the server are compiled in the WAP gateway in the MIME type WMLC (Wireless Markup Language Compiled) and transmitted to the client. For this purpose, the gateway takes on tasks (such as syntactic analysis of the WML pages) that the browser performs on the web.
Communication between the server and the WAP gateway uses the HTTP protocol established on the web . The communication between gateway and WAP client takes place (up to WAP 1.2) via WSP . With regard to the use of the carrier on the radio link, WAP is flexible, possible for example are Circuit Switched Data (CSD), High Speed Circuit Switched Data (HSCSD), General Packet Radio Service (GPRS), but also Universal Mobile Telecommunications System (UMTS) and High Speed Downlink Packet Access (HSDPA). The GSM-specific USSD transmission service can also be used.
WAP is used as the basic technology for MMS . Both the sending and receiving of a multimedia message are based on WAP. The information that such a message is available for download is sent to the mobile phone as a WAP push.
The WAP standard (from WAP 1.2) supports a push service that allows messages including a URI to be sent to the WAP client without a request. For the user, the WAP push service looks very similar to an SMS or MMS . Technically, this involves signaling via SMS or - with GPRS or UMTS - also via Service Indication (WAP-167 ServiceInd) (SI) or Service Loading (WAP-168-ServiceLoad) (SL).
WAP 1.0 to 1.2
The WAP Forum adopted the WAP 1.0 standard in 1997. WAP 1.0 is based on the Handheld Device Markup Language ( HDML ), which was developed by Unwired Planet (now Openwave ). However, the standard was not fully developed and there was a lack of appropriate browser software and WAP-capable end devices. So it could not establish itself commercially and was practically of no importance.
In 1999 the 1.1 standard was published, which in particular adopted the XHTML conventions. It was not compatible with WAP 1.0. WAP 1.1 was also able to establish itself on the end device market, so that soon most cell phones were equipped with a WAP browser. WAP 1.2, which was presented at the end of 1999, is primarily an improvement on WAP 1.1. The most important enhancements are the push service and so-called user agent profiles for WAP browsers , which allow the formatting of transmitted WAP pages to be displayed comfortably adapt the specific browser software used.
The specification of WAP 2.0 has largely dispensed with mobile-specific features and the original WAP protocols WSP , WTP , and WTLS through HTTP and SSL replaced. This makes the transition to the Internet much easier. WAP 2.0 struggles with speed problems with CSD and GPRS. As a rule, all normal Internet sites can be reached via WAP 2.0; Due to the low speed of GPRS, however, many can only be used meaningfully with EDGE or UMTS .
With WAP 2.0, the proxy concept was also weakened. The standard now also provides the option for the client to communicate directly with the web server, bypassing the gateway. However, a proxy offered by the mobile network operator can also be used. The independence from a proxy eliminates the dependency on the correct functioning of the WAP gateway, but has the disadvantage that there are already WAP 2.0 clients that no longer support WSP. They can then no longer use the available WAP proxies.
The use of Internet access via WAP 2.0 is normally charged by the mobile phone providers as direct Internet access. With GPRS or UMTS, costs are usually incurred for each page depending on the exact data volume, while with WAP 1.x it is usual to only be billed per page (i.e. per link clicked). In some tariffs, this means that the costs per page view for data-intensive HTML pages can be significantly higher than for WAP 1.x; however, very small pages can also be cheaper.
Some mobile phone manufacturers write in the information about their devices that they are WAP 2.0-capable devices, but do not mean the transmission technology, but only the fact that the devices can also display XHTML pages instead of just WML pages. However, the WAP 1.x settings must still be entered in the WAP settings.
Payment services can be processed via WAP. Since WAP pages are usually indistinguishable from other Internet pages, the use of chargeable services can occur unintentionally and unexpectedly, combined with the transmission of the phone number to the service provider or an intermediary debt collection company.
Dissemination and use
Since, after the introduction of WAP technology, mobile customers were initially unable to fall back on faster data transmission standards such as GPRS or HSCSD and the billing in data traffic was usually based on time, scoffers liked to jokingly explain the abbreviation as " W ait A nd P ay", English for " wait and pay ”. While the initial speed problems no longer exist, WAP remains disproportionately expensive for the content offered, despite the flat rates introduced with normal billing per click or per data packet compared to the generally significantly lower internet fees via mobile access. This is also one of the reasons why WAP technology has only gained limited acceptance despite some useful offers.