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Wireless Application Protocol (WAP)

By AFFAN HAIDER
June 18 - 24, 2001

Mobile computing, another one of the buzz words which we hear so often nowadays. Mobile computing is not a single industry or a technology, actually it is an idea, an initiative or a vision. A vision to free many important functions from so called limitations. Whether it is removing the chains of cables from internet, breaking the shackles of going to office for employees, using wireless telephones for accessing internet or simple use of laptops or notepads to keep in touch with the office while you are away. Everything meaning freedom in business language is what mobile computing is all about.

As already mentioned, there are many aspects of mobile computing, one of them coming up and becoming very popular quickly is the WAP. WAP stands for Wireless Application Protocol. Internet for quite some time now has proven to be an easy and efficient way of delivering services to millions of "wired" users. The motive behind WAP is to bring the convenience of Internet into the wireless community as well. WAP could easily be defined as a set of protocols, which have inherited their characteristics and functionality from internet standards and standards of wireless services developed by some of the world's leading companies in the business of wireless telecommunications.

It all began with Ericsson initiating a project in 1995, to develop a general protocol for value added services on mobile networks. The protocol was named Intelligent Terminal Transfer Protocol (ITTP), and is used to handle the communication between a service node, where the service application is implemented, and an intelligent mobile telephone. In 1996-97, different companies came up with certain other standards. Handheld Device Markup Language (HDML) and Handheld Device Transport Protocol (HDTP) were a few examples. Just like HTML for internet, HDML is used for describing content and user interface, but optimised for wireless internet access from handheld devices with small displays and limited input facilities. Later in 1997, Smart Messaging concept was introduced. The communication between the mobile user and server containing internet information uses Short Message Service (SMS) and a markup language called Tagged Text Markup Language (TTML). As solutions being offered were fragmented and at times incompatible with other solutions, different companies joined hands to form what we have come to know as WAP.

The Internet Model vs. The WAP Model:

To understand the difference let's first look at the illustrations of Internet and WAP models.

Why WAP?

One question that comes to the mind is that in the presence of existing internet and wireless communication standards why was it necessary to introduce a new standard. A simple answer to that would be the constraints. You can not expect to get same sort of service or graphics etc. using mobile phones or even laptops as one gets from the usual desktop computer. WAP has been designed to meet the constraints of a wireless environment. Both limitations in the network and in the client are taken into consideration.

Limitations of Wireless Network & Wireless Device, how WAP responds:

The most important issues in the network addressed by WAP are summarized below:

Low Bandwidth: WAP addresses the issue of low bandwidth by minimizing the traffic over the air-interface. WML (Wireless Markup Language) and WML Script are binary encoded into a compact form when sent over the air in order to minimize the number of bits and bytes.

WSP, WAP's equivalent to HTTP on the internet is also binary for the same reason. Moreover, it supports long-lived sessions, that can be suspended and resumed, and header caching; saving valuable bandwidth.

High Latency: The latency period is being eliminated in WAP by using the concept of scripting, so as to avoid latency due to problems such as user login etc. The Wireless Telephony Application environment addresses latency, by introducing the repository, which is a persistent storage container used for housing services which should be started in response to an event in the mobile network. Since these services are readily available, no roundtrips to the server are required.

Less connection stability/unpredictable bearer availability: This problem is addressed by allowing lost sessions to be resumed, even when dynamically assigned IP addresses are used. Connections do not setup therefore the effects of lost bearer and times of inactivity are minimized.

Small Display: Due to smaller display available, instead of using the flat document structure HTML provides, WML structures its document in decks and cards. A card is a single unit of interaction with the end-user. A card is typically small enough to be displayed even on a small screen.

Limited Input Facilities: Compare your keyboard with the buttons available on your handheld mobile set, the difference is quite drastic. For this the elements that are used in WML can be easily implemented so they make very humble requirements on the keyboard. Rather than this more use of navigation is implied.

Limited memory and CPU: WAP addresses the issue by defining a lightweight protocol stack adapted to its purpose. The limited set of functionality provided by WML and WML Script makes it possible to implement browsers that make small claims on computational power and ROM resources. When it comes to RAM, the binary encoding of WML helps keeping the RAM usage as low as possible.

Advantages of WAP:

So, what's in it for me, is the usual question which comes with every new technology. There are many advantages for many different set of users, considering you as subscribers you can expect the following:

• Portability
• User friendliness
• Access to a wide variety of services on a competitive market
• Possibility of having personalized services
• Fast, convenient and efficient access to services
• To fulfil as many customers needs as possible, WAP devices will be available in various form factors, e.g. pagers, handheld PCs and mobile phones.

As we are experiencing the introduction of certain value added services by the service providers in Pakistan nowadays, it would be a good bet to believe that WAP is not that far away. Another exciting prospect wouldn't you agree.