Wireless Application Protocol

WAP is a general small application protocol mainly for small handheld communication devices like cellular phones and PDAs. WAP was originally founded by the cellular equipment giants Nokia, Ericsson, and Motorola and the handheld device software platform developer Unwired Planet, since that several dozens of companies, mainly hardware and software manufacturers and network operators, have joined the WAP and are developing all kinds of devices, applications, and services.

3. General

WAP has been designed from various currently used Internet standards like HTML, HTTP, XML, TCP, IP, UDP, and TLS. The main points in developing this new protocol were to make it very bandwidth optimised to work as quickly as possible in slow wireless networks (compared to fixed line networks that conventional protocols are designed for) and flexible to work in small screens of different shapes and various user input devices. Bandwidth requirements are made low by transferring all information as compressed binary and not as plain text as current similar protocols like HTTP. Header information is optimised to be small and the page markup language supports making applications small and flexible.

WAP is an evolving standard. The current version of specifications is 1.0 which was released in April 1998 and the next version, v1.1, is being developed by feedback regeived from the first version and will be approved in May 1999.

4. Wireless vs Fixed

• Less powerful processors of various architectures
• Less RAM, ROM, and secondary storage space
• Limited supply of power
• Small displays of non-standard shapes
• Different input devices (phone keypad, roll selector, touch sensitive screen, etc.)

• Less bandwidth
• More latency (both in connecting and transferring information)
• Less connection stability
• Less predictable availability (blind spots, weak fields)

• Interoperable - terminals from different manufacturers communicate with services in the mobile network
• Scaleable - mobile network operators are able to scale services to customer needs
• Efficient - provides quality of service suited to the behaviour and characteristics of the mobile network
• Reliable - provides a consistent and predictable platform for deploying services
• Secure - enables services to be extended over potentially unprotected mobile networks while still preserving the integrity of user data; protects the devices and services from security problems such as denial of service

• Leverage existing standards where possible
• Define a layered, scaleable, and extensible architecture
• Support as many wireless networks as possible
• Optimise for narrow-band bearers with potentially high latency
• Optimise for efficient use of device resources (low memory/CPU usage/power consumption)
• Provide support for secure applications and communication
• Enable the creation of Man Machine Interfaces (MMIs) with maximum flexibility and vendor control
• Provide access to local handset functionality, such as logical indication for incoming call
• Facilitate network-operator and third party service provisioning
• Support multi-vendor interoperability by defining the optional and mandatory components of the specifications
• Provide a programming model for telephony services and integration

Figure 1 - The WAP Protocol Stack.

6.1 Wireless Application Environment (WAE)

Figure 2 - WAP Client-Server Architecture

The gateway- and origin servers may be integrated into a single WAP server that will directly deliver WML data for WAP requests. The server may also include a WTA (Wireless Telephony Application) server that can be directly connected by the mobile data terminal's data bearer layer like GSM SMS to speed up connections. The Nokia WAP server currently piloting is such integrated origin, gateway and WTA-server.

8. Current Status

Although, there are no actual WAP devices on the market yet, some have been introduced and many others are under development. For developing and previewing WAP applications there is the Nokia WAP SDK that is a Java-based application that emulates a WAP-enabled cellular phone and can be used to create WAP applications with any computer with a recent Java Runtime Engine.

The first WAP device introduced was the Nokia 7110 which looks much like any current mobile phone but has a relatively big display and a rolling wheel as an input device. The 7110 was introduced in the Cannes GSM World Conference 29.2.1999 and will be available in volume (according to the press release) in the second quarter of 1999.

Ericssons first WAP product will be the MC218 Mobile Companion that has the Psion V handheld computer as it's hardware platform and Symbian's WAP-enabled EPOC operating system with Ericsson's extensions and applications. The MC218 was introduced 12.3.1999 and will be available (according to the press release) during mid 1999.

Another WAP device by Ericsson will be the R380 mobile phone/PDA that will have size of current mobile phones and a large screen under a protective lid. The R380 was introduced in CeBIT 18.3.1999 and should be available in early 2000.

9. The Future - Conclusion

The currently introduced devices will cover a wide base of customer needs when they hit markets and many more are following since most mobile phone manufacturers are developing new ones to keep up with others. According to mobile phone manufacturers committed to WAP, most mobile phones will be WAP-enabled in a couple of years and since all major mobile phone manufacturers do support WAP, there doesn't seem to be anything in the way of WAP success.

Appendix A - Examples of WML and WMLS

<b><?XML VERSION="1.0"?> 
<WML> 
  <CARD NAME="card1" TITLE="Mortgage Calc" NEWCONTEXT="TRUE"> 

    Principal: <INPUT FORMAT="*N" KEY="principal"
                TITLE="Principal:" DEFAULT="150000"/> 
    <BR/>
 
    Interest:  <INPUT FORMAT="*N" KEY="interest" TITLE="Interest:" DEFAULT="8.00"/> 
    <BR/> 
 
    Num payments:<INPUT FORMAT="*N" KEY="num_payments"
                  TITLE="Num. payments:" DEFAULT="360"/> 
    <BR/>
 
    Payment = <U>$(payment)</U> 
 
    <DO TYPE="ACCEPT" LABEL="Calculate"> 
      <GO URL="mortgage.wmls#payment('$(payment)','$(principal)',
               '$(interest)','$(num_payments)')"> 
      <VAR NAME="payment" VALUE="payment"/> 
      </GO> 
    </DO> 
 
    <DO TYPE="HELP" LABEL="Help"> 
      <GO URL="#help"/> 
    </DO> 

  </CARD> 
 
  <CARD NAME="help" TITLE="Help">

    <U>Principal</U> - $$ amount<BR/> 
 
    <U>Interest</U> - e.g. 0.075.<BR/> 
 
    <U>Payments</U> - e.g. 360 for 30 years<BR/> 
    	 
    <DO TYPE="PREV" LABEL="Back"> 
      <PREV/> 
    </DO> 

  </CARD> 
</WML> 

/* 
 * Calculate a mortgage's payment 
 * 
 *@param varname the variable name to store the result 
 *@param principal the principal 
 *@param interest the interest rate 
 *@param num_payments the number of payements 
 *@return the payment 
 */ 
external function payment(varname, principal, interest, num_payments) { 
	/*
	 * Interest formulae:
	 *
	 * If (i != 0), then:
	 * 		pmt = principal * [i * (1+i)^n / ((1+i)^n - 1)]
	 *
	 * If (i == 0), then:
	 * 		pmt = principal / n
	 */
    var mi = interest/1200;	// monthly interest from annual percentage 
    var payment;
	if (mi != 0) {
		var tmp = Float.pow((1 + mi), num_payments);
		payment = principal * (mi * tmp / (tmp - 1));
	} else {
		payment = principal / num_payments;
 	}
    var s = String.format("$%6.2f", payment); 
 
	/* 
 	 * Send the result to the browser 
	 */ 
    WMLBrowser.setVar(varname, s); 
 
	/* 
	 * Make sure the browser updates its current card 
	 */ 
    WMLBrowser.refresh(); 
}; 

WAP Forum is the official coalition between all parties committed to WAP and its home page has most of technical and non-technical information about WAP released to the public. WAP Forum home page is a good source for general information, list of members, technical specifications and other technical documents.

Another useful site is the Nokia Wireless Data Forum at http://www.forum.nokia.com. The Nokia WAP SDK, its documentation and WAP reference manuals may be obtained from the Wireless Data Forum after free registration.