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Wireless Application Protocol
 
Wireless Application Protocol

Using J2EE platform
According to industry analysts, the number of Internet users would exceed the 350 million mark by the turn of the millennium. These users access the Internet primarily through wire line channels from PCs. Estimates indicate that the number of mobile phone users using voice service is over 300 million subscribers. Mobile phone users and industry alike feel the need for enhanced data services like web browsing and e-mail offered by Internet to the wire line user community. In 1997, Ericsson, Motorola, Nokia and Unwired Planet (now Phone.com) founded the WAP Forum to design a common wireless protocol specification for offering advanced data services. The key goal of WAP Forum was to create an open protocol specification for bringing the Internet content to wireless phones and terminals. Today, a large number of wireless device manufacturers and mobile network operators are using the WAP specifications to enhance their product lines and services. The network operators are effectively using WAP to increase their revenues and customer base, at the same time offering a significant value addition to their subscribers. Wireless Application Protocol (WAP) is an open license-free specification defined by an industry group called WAP Forum (http://www.wapforum.org). WAP Forum has members representing different sections of wireless and Internet industry like handset vendors, network operators, infrastructure providers, software developers, Internet content developers and service providers. Article further discusses features, Architecture, Wireless Datagram Protocol (WDP), Wireless Transaction Layer Security (WTLS), Market Potential of the WAP.

Introduction
Wireless Application Protocol (WAP) is a communications protocol that formats Web data for transmission over wireless Internet connections, letting you surf with a mobile phone or other wireless device. If access to e-mail and the Web is critical to your mental and fiscal well-being, you need to know about the Wireless Application Protocol. Using a wireless Web service and a mobile phone, pager, or other wireless device that supports WAP, you can tap into the Web from almost anywhere, vendors claim. Faster wireless Internet access and an increasing number of Web sites that support WAP mean that wireless Web surfing could be the wave of the future. The WAP specification is a result of WAP Forum's effort to develop a global wireless Internet standard, which brings information, and advanced services available on the Internet to mass market, hand-held wireless devices such as digital cellular phones, PDAs, pagers, two-way radios and other wireless terminals. WAP specification enables development of applications that can offer services like e-mail, web browsing, on-line shopping, on-line banking, on-line ticketing, stock quotes, etc., to an end user on his or her mobile phone.

 
 

WAP is simply a protocol- a standardized way that a mobile phone talks to a server installed in the mobile phone network. It is amazing how in just six months, it has become imperative for all Information Technology companies in Nordic countries and beyond to have a WAP division.

With the proliferation of wireless devices in the late 1990s, the need for an industry-standard protocol became evident. In response to this trend, the WAP Forum, an industry association co-founded in 1997 by Phone.com, Ericsson, Motorola and Nokia, formed the Wireless Application Protocol (WAP) specification.

WAP is an open, global specification based on IP and XML that supports the standard data formatting and transmission of wireless devices. It empowers mobile users with wireless devices to easily-and-instantly access and interacts with information and services. WAP provides Internet communications and advanced telephony services on mobile phones, pagers, PDAs, two-way radios, smartphones and other wireless terminals.

WAP is designed to work with most wireless networks, including CDPD (Cellular Digital Packet Data), CDMA (Code Division Multiple Access), GSM (Global System for Mobile Communications), personal digital communications, Personal Handyphone System, TDMA (Time Division Multiple Access), FLEX, Reflex, iDEN, TETRA, DECT, DataTAC and Mobitex, and includes WML (Wireless Markup Language), a definition of an XML syntax. Moreover, WAP can be built on any operating system and provides service interoperability between different device families.

Java 2 Enterprise Edition:
Java TM 2 Platform, Enterprise Edition (J2EE), is a standard architecture to define and support a multi tiered-programming model where thin-client applications invoke business logic that executes on an application server. With this model, developers can focus on solving business problems, leverage the power and speed of server-side technology, and leave the low-level programming details to the architecture.

To reduce costs and fast-track enterprise application design and development, the JavaTM 2 Platform, Enterprise Edition (J2EETM) technology provides a component-based approach to the design, development, assembly, and deployment of enterprise applications. The J2EE platform gives you a multitiered distributed application model, the ability to reuse components, a unified security model, and flexible transaction control. Not only can you deliver innovative customer solutions to market faster than ever, but your platform-independent J2EE component-based solutions are not tied to the products and APIs of any one vendor.

Motivation
During the last couple of years, the Internet has grown at a tremendous pace and has proved to be an easy and efficient way for delivering services to millions of wire line users. Parallel, wireless voice communication has grown at an equally rapid pace and gained wide acceptance. However, both these technologies have certain shortcomings:

  • The Internet requires wire line connectivity for accessing the services, posing a problem to those users who spend substantial amount of their time on the move.

  • Today's wireless network infrastructure does not have the flexibility required for rapid deployment of wireless data services like telephony services.

The Internet and wireless industries realized that Wireless Internet could be a single solution that can effectively address the shortcomings of both these technologies. Wireless Internet not only enables accessing the services offered by Internet from mobile phones thereby overcoming the constraint imposed by the Internet, but also allows the network operators to host wireless data services on Internet platform. Early efforts at unifying the Internet and wireless technologies to launch wireless services were not very successful. Such attempts were made by independent wireless data carriers using proprietary technologies that were bound to fail due to a fragmented market and low economies of scale. The WAP Forum was founded by Ericsson, Motorola, Nokia and Unwired Planet (now Phone.com) to develop standards to make universal wireless Internet access a reality. The WAP specification was developed by WAP Forum to adapt the Internet technology to address issues specific to wireless environment. The inherent constraints of wireless network technology like limited bandwidth, high latency, and unpredictable availability and less reliable connection stability are adequately addressed by the WAP specification. The WAP specification also deals with issues related to wireless devices like limited computational capability, small memory size, limited battery power, limited input mode and small display size.

Features
WAP can be loosely described as a set of protocols derived from existing Internet standards and wireless network standards developed by some of the leading companies in wireless business. Following are some of the key features of WAP:

1. Interoperability: WAP is an open license-free standard, which ensures that WAP-compliant devices are interoperable.

2. Scalability: WAP applications scale across a variety of wireless transport options like GSM SMS, GSM USSD, IP, CDMA, etc., and also across a wide range of wireless terminals from hand sets to powerful PDAs.

3. Extensibility: WAP has been designed as a future-proof technology. It is extensible over time to new networks and transports thereby protecting the mobile network operators' investment in wireless data.

4. Flexibility: WAP is a flexible solution that caters to the requirements of various types of applications by providing service options like connection mode and connection-less services, with or without end-to-end security.

5. Reusability: WAP specification extends and adapts existing Internet standards such as HTTP, IP, Proxy technology, SSL, TLS, XML, HTML, etc., to wireless environment instead of defining a new set of standards, facilitating utilization of existing Internet infrastructure as is. This approach benefits the content developer community by allowing familiar programming models, proven architectures and averaging existing tools like authoring and publishing applications.

Architecture
The layered architecture model of WAP stack is illustrated in Figure 1. The WAP stack consists of four protocols - WSP, WTP, WTLS and WDP along with an application environment framework (WAE). A prominent feature of the WAP stack is that an application or service can directly access any of the four underlying layers through a set of well-defined interfaces based on the needs of the application as shown in Figure 1.

 
 

Figure 1: WAP Architecture.

The WAP stack can be configured in four different ways to provide four different types of services. Following are the four types of services offered by WAP:

1. Connectionless service: The WAP protocol stack used for this service consists of only WSP layer operating directly over WDP layer.

2. Connectionless service with security: This configuration is similar to connectionless service but provides security by having WTLS layer between WSP and WDP layers.

3. Connection oriented service: The configuration of protocol stack used for this service consists of WSP, WTP and WDP layers with ordering of the layers same as that shown in Figure 1. WTP and WDP layers together provide a connection oriented transport service in this configuration.

4. Connection oriented service with security: This configuration consists of all the layers of WAP stack as shown in Figure 1. WAP protocols have been designed to operate transparently over data capable wireless networks supporting different data transport mechanisms (bearers), which include packet data networks, short message services and circuit-switched data networks. Some of the bearers, which are currently supported by WAP, are GSM SMS, GSM USSD, CSD, IPv4, IPv6 and CDMA.

The following paragraphs describe different protocol layers and application environment of WAP in detail.

Wireless Datagram Protocol (WDP)
WDP provides the higher layers of the stack with an insistent interface to underlying bearer. WDP operates transparently over one of the available bearer services thereby making the upper layers of the WAP stack independent of the bearer. Since the services offered by underlying bearers vary widely, WDP contains adaptation layers to map WDP functions to services offered by different bearers. The functionality of WDP when operating on IP bearer is exactly same as the Internet standard User Datagram Protocol (UDP). WDP provides a connection-less, unreliable datagram service. WDP supports simultaneous communication instances from a higher layer over a single underlying bearer service. WDP uses port numbers to address higher layer entities as in transport layer of the Internet protocol stack. WDP can be extended to support optional error reporting mechanism by adding Wireless Control Message Protocol (WCMP) functionality, which is similar to Internet Control Message Protocol (ICMP).

Wireless Transaction Layer Security (WTLS)
WTLS operates over WDP and provides the upper layers with a secure transport service interface, which preserves the transport service interface of WDP. WTLS provides end-to-end security features, which include:

  • Confidentiality using data encryption algorithms
  • Data integrity using Message Authentication Codes
  • Non-repudiation and strong authentication using digital certificates

In addition to connection security, WTLS also offers on-the-fly payload compression service. WTLS is a derivative of the Internet standard TLS (RFC 2246) protocol with optimizations required to operate effectively on a datagram service running on a low-bandwidth network.

Wireless Transaction Layer (WTP)
WTP layer provides a lightweight transaction service, i.e., a request/response service, which can operate efficiently over a secure, or insecure datagram service. It provides three classes of service, namely,

  • Unreliable push service
  • Reliable push service
  • Reliable transaction service

The features of WTP are selective retransmissions, duplicate removal, segmentation/reassembly, port number addressing, user-to-user reliability (through user-to-user acknowledgements) in addition to protocol acknowledgements, asynchronous Transactions, optional out-of-band information, delayed acknowledgements and message concatenation to improve over-the-air efficiency. WTP is message-oriented protocol, which makes it suitable for interactive browsing applications.

Wireless Session Protocol (WSP)
WSP layer provides mechanisms and semantics based on the Internet standard, Hyper Text Transfer Protocol (HTTP/1.1) along with additional functionalities such as:

  • Protocol feature negotiation (capability negotiation)
  • Compact encoding of data
  • Session suspend/resume
  • Long lived session states
  • Asynchronous requests
  • Common facility for confirmed and non-confirmed data push

Other than these additional features added to address issues in a low-bandwidth net.

Wireless Application Environment (WAE)
WAE provides a network neutral and device independent application environment framework, which enables a wide range of applications (user-agents) to be used on wireless terminals. WAE is consistent with the Internet/WWW programming model including authoring and publishing methods. WAE allows the MMI to be controlled by the vendor of the handset. WAE is designed to leverage on standard Web Servers (origin servers) to host content and services. The content is addressed using the Internet standard URLs and URIs.

Following are the various components of WAE:

  • Wireless Markup Language (WML)
  • WML Script
  • WAP Content Types
  • Wireless Telephony Application (WTA) environment

WML is a tag based markup language, which is derived from XML and is similar to the Internet standard HTML. WML addresses the constraints such as small displays, limited user-input capability, narrow-band network connections, limited processing power and limited memory resources in a wireless device. The key features of WML are navigation support, hyperlinks, soft-button support, screen management (displaying formatted text, images) and user data input (text, selection lists).
WMLScript is a lightweight procedural scripting language. It is an extended subset of JavaScript TM scripting language. It enhances the presentation facilities offered by WML and supports advanced dynamic UI behavior by adding intelligence on the client side. WAP defines several content formats based on standard WWW content formats that facilitate interoperable data exchange. All WAP content is specified in one of the defined content formats. As in WWW content formats, a header contain-ing content type field allows the micro-browser to process the content based on its type. The two most important formats defined by WAP are encoded WML and WMLScript formats. WAP defines binary encoding formats for WML and MLScript to make transmission of these content types more efficient as well as to minimize the processing effort needed on the client. Additionally standard WWW content formats for images, calendar data formats (vCalendar 1.0), electronic business cards (vCard 2.1) are also supported. WTA provides extensions for telephony services like call and feature control mechanisms, voice mail, messaging, phone-book management, etc., to make them accessible to WAP content developers. WTA framework also allows real-time processing of events important to the end-user while browsing. WTA provides a library of telephony-related functions called Wireless Telephony Application Interface (WTAI) that can be invoked from WML/WMLScript. WTAI can be used to perform functions like call-management, call set-up, answering an incoming call, etc. WAE typically consists of two user-agents: a micro-browser and a telephony application. A micro-browser is similar to a web browser such as Netscape Navigator or Internet Explorer with additional optimizations required to run on a consumer handset. A micro-browser interprets WML/WMLScript content types. A telephony application is used for providing telephony services offered by WTA to end-user. WWW content (e.g., HTML), a filter is used to translate the WWW content to WAP content. A WAP network need not have all the elements shown in Figure 2. An origin server itself may support both WAP proxy and filtering functionality, in which case, a wireless device can directly contact the origin server. This type of configuration can be used to facilitate end-to-end security solutions, better access control or guarantee of responsiveness.

Market Potential
As WAP aims at bridging two of the most successful technologies of the communication revolution - Internet and Wireless, the success of WAP is assured. Market studies show that the share of global wireless communication revenues - as a percentage of the total telecommunication revenues - is consistently on the rise (from a mere 5% in 1992 to around 20% in 2000). With telecommunication industry revenues touching the US $1000 billion mark and growing at a rate of 7%, the industry is all set to reach the US $1.5 trillion size by 2004. Close to a quarter of these revenues would be from the wireless domain - where WAP enabled product vendors, service providers and network operators would meet the advanced data needs of over 500 million subscribers.

Global R&D Solutions offers following WAP solutions:

1. Enterprise WAP Gateway

2. Embedded WAP Client Solution

3. WAP Service/Application Development

Enterprise WAP Gateway
Enterprise WAP Gateway is a high performance, scalable solution suitable for deployment in a corporate intranet environment. It can be used as a platform for hosting corporate wide applications including, but not limited to, enterprise messaging, appointment, calendar, contacts list, corporate database, intranet portals, etc.

Following are the main features of Enterprise WAP Gateway:

  • Scalable, high performance architecture
  • Works on ubiquitous UDP/IP network
  • Optional customized security module (WTLS)
  • WAP Proxy support for accessing other intranet servers
  • Open API similar to BSD Sockets to facilitate easy migration of existing applications and development of new applications
  • Interoperable with any WAP compliant mobile terminal
  • Seamless integration with existing enterprise web servers
  • Web based tool for configuration and remote administration

Enterprise WAP Gateway is currently available on Linux and Solaris plat-forms. Microsoft Windows NT port will be available soon.

Embedded WAP Client Solution
WAP client solution for wireless information terminals running embedded operating systems like PalmOS, VxWorks, Windows CE, etc. WAP client solution consists of client-side WAP stack and a microbrowser. The client-side WAP stack currently supports IP bearer and it can be customized to run on a wide gamut of wireless mobile devices supporting different bearer network technologies. Also, the flexible architecture of client-side WAP stack allows the stack to be customized and tuned for optimum performance and memory footprint on a variety of wireless terminals. The microbrowser is based on highly modular design and can be customized to work on a wide range of devices from mobile phones to PDAs with different display and input capabilities.

J2EE Architecture

 
 

The component-based and platform-independent J2EE architecture makes J2EE applications easy to write because business logic is organized into reusable components and the J2EE server provides underlying services in the form of a container for every component type. Because you do not have to develop these services yourself, you are free to concentrate on solving the business problem at hand.

Containers and Services
Component is installed in their containers during deployment and is the interface between a component and the low-level platform-specific functionality that supports the component. Before a web, enterprise bean, or application client component can be executed, it must be assembled into a J2EE application and deployed into its container.

The assembly process involves specifying container settings for each component in the J2EE application and for the J2EE application itself. Container settings customize the underlying support provided by the J2EE Server, which include services such as security, transaction management, Java Naming and Directory Interface TM (JNDI) lookups, and remote connectivity. Here are some of the highlights:

  • The J2EE security model lets you configure a web component or enterprise bean so only authorized users access system resources.

  • The J2EE transaction model lets you specify relationships among methods that make up a single transaction so all methods in one transaction are treated as a single unit.

  • JNDI lookup services provide a unified interface to multiple naming and directory services in the enterprise so application components can access naming and directory services.

  • The J2EE remote connectivity model manages low-level communications between clients and enterprise beans. After an enterprise bean is created, a client invokes methods on it as if it were in the same virtual machine.

The fact that the J2EE architecture provides configurable services means that application components within the same J2EE application can behave differently based on where they are deployed. For example, an enterprise bean can have security settings that allow it a certain level of access to database data in one production environment and another level of database access in another production environment.

The container also manages non-configurable services such as enterprise bean and Servlet life cycles, database connection resource pooling, data persistence, and access to the J2EE platform APIs described in J2EE APIs. Although data persistence is a non-configurable service, the J2EE architecture lets you override container-managed persistence by including the appropriate code in your enterprise bean implementation when you want more control than the default container-managed persistence provides. For example, you might use bean-managed persistence to implement your own finder (search) methods or to create a customized database cache.

Conclusions
The primary focus of WAP technology is to create a global wireless Internet by bringing services offered by Internet to mobile phone users. Industry leaders in handset manufacturing representing over 90% of the world market and mobile network operators representing about 300 million subscribers are adopting this technology. WAP has been designed to benefit wireless subscribers, handset vendors, network operators and service providers. Subscribers get access to a wide range of services available on Internet from their mobile phones and other wireless interoperable open standard, which is handset vendor independent.

Case Studies

Project: WEATHER INFORMATION SYSTEM

Introduction
The Weather Information System is designed and developed by using WAP technology to display the current Climatic conditions such as Max Temperature and Min Temperature of selected cities of the world.

Architecture
The Architecture used shown below.

 
 

Project Details

The following are some of the screens developed for the Weather Information System.

 
 
Conclusion
This Application is extensively tested and implemented successfully on Nokia WAP emulator and then on Nokia 7120 device using WAPServ gateway. When the user request for a URL on the the WAP Phone browser, The WAP Phone (Nokia 7120) communicate with WAP Gateway (WAPServ Gateway) through Remote Access Service (RAS) Server dialup. The WAP Gateway in turn communicates with Web Server (Apache on Linux) using dedicated line and convert WAP Request to Http request.

The web server (Apache on Linux) get the Http request thro' WAP gateway and process the request thro' Java Servlets and interact with database (Oracle) and send the Http response in WML embedded in servlets to WAP Gateway. WAP gateway converts Http response to WAP response and sends the WML contents to the device (Nokia 7110) for displaying WAP contents.
 
 
 
 
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