Wireless Applications And Devices

Providing Internet and World Wide Web (WWW) services on a wireless data network presents many challenges because most of the technology developed for the Internet has been designed for desktop and larger computers that support medium to high bandwidth connectivity over generally reliable data networks.

Mobile and wireless devices are usually handheld devices, and accessing the WWW presents a more constrained computing environment compared to desktop computers because of fundamental limitations of power and form factor. Mass-market handheld wireless devices tend to have

• less powerful CPUs (Central Processor Units)

• less memory [both ROM (Read Only Memory) and RAM (Random Access Memory)]

• restricted power consumption

• smaller displays

• different input devices (e.g., a phone keypad, voice input, etc.).

Wireless data networks also present a more constrained communication environment compared to wired networks. Because of fundamental limitations of power, available spectrum, and mobility, wireless data networks tend to have

• less bandwidth than traditional networks;

• more latency than traditional networks;

• less connection stability than other network technologies; and

• less predictable availability.

Mobile networks are growing in complexity and the cost of providing new value-added services to wireless users is increasing. To meet the requirements of mobile network operators, solutions must be

• interoperable - terminals from different manufacturers communicate with services in the mobile network;

• scalable - mobile network operators should be able to scale services to customer needs;

• efficient - provide quality of service suited to the behavior and characteristics of the mobile network; provide for maximum number of users for a given network configuration;

• reliable - provide a consistent and predictable platform for deploying services;

• secure - enable services to be extended over potentially unprotected mobile networks while still preserving the integrity of user data; protect the devices and services from security problems such as denial of service.

The WAP Forum is an industry group dedicated to the goal of enabling sophisticated telephony and information services on handheld wireless devices such as mobile telephones, pagers, Personal Digital Assistants (PDAs), and other Wireless Terminals (WTs). Recognizing the value and utility of the WWW architecture, the WAP Forum has chosen to align certain components of its technology very tightly with the Internet and the WWW. The WAP specifications extend and leverage mobile networking technologies (such as digital data networking standards) and Internet technologies, such as IP, Hypertext Transfer Protocol (HTTP), Extensible Markup Language (XML), Uniform Resource Locators (URLs), scripting, and other content formats.

The WAP Forum drafted a global wireless protocol specification for all wireless networks and contributes it to the industry and standards bodies. WAP enables manufacturers, network operators, content providers, and application developers to offer compatible products and secure services on all devices and networks, resulting in greater economies of scale and universal access to information. The objectives of the WAP Forum are

• to bring Internet content and advanced data services to digital cellular phones and other WTs;

• to create a global wireless protocol specification that works across different wireless network technologies;

• to enable the creation of content and applications that scale across a very wide range of wireless bearer networks and wireless device types;

• to embrace and extend existing standards and technology wherever appropriate.

To bring Internet and WWW technologies to digital cellular phones and other WTs, that is, adapting the Web architecture to the wireless environment, and to enable the delivery of sophisticated information and services to mobile WTs requires working toward a unified information space, common standards, and technologies.

Wireless network bearers operate under several fundamental constraints, which place restrictions on the type of protocols and applications offered over the network:

• Power consumption: As bandwidth increases, power consumption increases. In a mobile device, this reduces battery life.

• Cellular network economics: Mobile networks are typically based on a cellular architecture. Cells are a resource shared by all mobile terminals in a geographic area and typically have a fixed amount of bandwidth to be shared among all users. This characteristic rewards efficient use of bandwidth, as a means of reducing the overall cost of the network infrastructure.

• Latency: The mobile wireless environment is characterized by a very wide range of network latency, ranging from less than a second round-trip communication time to many tens of seconds. In addition, network latency can be highly variable, depending on the current radio transmission characteristics (e.g., in a tunnel or off network) and the network loading in a particular area. Latency is further increased by routing, error correction, and congestion avoidance characteristics of a particular network.

• Bandwidth: The mobile wireless environment is characterized by a very wide range of network characteristics and typically has far less bandwidth available than a wireline environment. In addition, the economics of the wireless environment encourage the conservation of bandwidth to achieve greater density of subscribers.

Wireless devices operate under a set of physical limitations, imposed by their mobility and form factor:

• Limited power: Any personal or handheld mobile device will have a very limited power reserve, owing to existing battery technology. This reduces available computational resources, transmission bandwidth, and so on.

• Size: Many mobile wireless devices are very small (handheld).

Mobile wireless devices are characterized by a different set of user interface constraints than that of a personal computer. To enable a consistent application-programming model, a very wide range of content scalability is required. In practice, a significant amount of the WWW content is unsuitable for use on handheld wireless devices. The problems include the following:

• Output scalability: Existing content is designed for viewing on PC (Personal Computer) screens, whereas mobile devices have a wide range of visual display sizes, formatting and other characteristics that include voice-only output.

• Input scalability: Mobile devices feature a wide range of input models, including numeric keypad, very few or no programmable soft keys, and so on, and voice-only input.

Many wireless devices, for example, cellular phones and pagers, are consumer devices. These devices are used in a wide variety of environments and in a wide range of scenarios. The examples include the following:

• Simple user interfaces: Many mobile devices, in particular, cellular telephones, are mass-market consumer-oriented devices. Their user interface must be extremely simple and easy to use.

• Single-purpose devices: The goal and purpose of most mobile devices is very focused (e.g., voice communication). This is in contrast with the general-purpose tool-oriented nature of a personal computer. This motivates a very specific set-of-use cases, with very simple and focused behavior, for example, placing a voice call.

• Hands-free, heads-up operation: Many mobile devices are used in environments in which the user should not be unnecessarily distracted (e.g., driving and talking).

The World Wide Web Consortium (W3C) is leading and participating in the continuing development of the Web and its standards. The new generation of Web technologies is intended to enhance the users' and publishers' control over the presentation of the information [e.g., through Cascading Style Sheets (CSS)], over the management of information [e.g., through Resource Description Framework (RDF)], and over its distribution [e.g., through P3P (Platform for Privacy Preferences Project)] on the basis of technologies that structure and distribute data as objects, such as XML and HTTP-NG (Network Group). These technologies will be described later in the text.

A new generation of Hypertext Markup Language (HTML) is based on XML and includes features that make it more efficient for mobile use. The other XML applications such as the Wireless Markup Language (WML) and the Synchronized Multimedia Integration Language (SMIL) have components where mobile access has an impact.

A Scalable Vector Graphics (SVG) format, which is written as a modular XML tagset and is usable as an XML name space, can be widely implemented in browsers and authoring tools and is suitable for widespread adoption by the content authoring community as a replacement for many uses of raster graphics. In simple cases such as in-line graphics, it should be possible to hand the author the SVG format, and it should also be possible to cut and paste SVG graphical objects between documents and to preserve their appearance, linking behavior, and style. The graphics in Web documents are smaller, faster, more interactive, and displayable on a wider range of device resolutions from small mobile devices through office computer monitors to high-resolution printers.

In the presentation model for the new generation of Web technologies, the formatting of a document is conducted through the use of a style sheet. This is a separate document that allows authors and users to attach style (e.g., fonts, spacing, and aural cues) to structured documents (e.g., HTML documents and XML applications). By separating the presentation style of documents from the content of documents, Cascading Style Sheets Level 2 (CSS2) and Extensible Stylesheet Language (XSL) simplifies Web and XML authoring and site maintenance. Local processing of a document might in the future also be conducted using a similar technology called action sheets. Style sheets can have media-specific properties, which makes them a possible candidate for use with mobile devices.

The Document Object Model is a platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of documents. The Document Object Model provides a standard set of objects for representing HTML and XML documents, a standard model of how these objects can be combined, and a standard interface for accessing and manipulating them.

The purpose of the HTTP-NG activity is to design, implement, and test a new architecture for the HTTP protocol on the basis of a simple, extensible, distributed object-oriented model. This includes a protocol for the management of the network connections, a protocol for transmitting messages between systems, a set of methods, interfaces, and objects that demonstrate a classical Web browsing case, as an example of what is possible with the new protocol and a test bed to test the implementation.

Accessibility for people with disabilities is relevant for mobile wireless devices as this is a potentially large marketplace (over 10% of the population), and in some cases accessibility is required (e.g., for sales in the United States, under Section 255 of the US Telecommunications Act). In addition, functions, such as speech input or output, required to accommodate different kinds of disability have carry-over benefits for nondisabled users of mobile devices, who may be using the devices in hands-free or eyes-free situations.

W3C's Web Accessibility Initiative (WAI), in coordination with other organizations, is addressing Web accessibility through several areas of work and related technology and guidelines to mobile wireless devices. In the area of technology, WAI works with W3C Working Groups developing technologies that can facilitate accessibility, such as HTML, CSS, SMIL, and SVG. In the area of guidelines, WAI is developing guidelines for accessible page authoring, user agents, and authoring tools and is coordinating with the development of guidelines by the Mobile Access Interest Group.

The correct representation of characters is an issue in all formats of writing, not just the Latin alphabet. The aim of this activity is for the WWW to live up to its name, and the W3C continues work on the internationalization of the Web with the aim of ensuring that the necessary features are included in W3C protocols and data format recommendations. The general goal of W3C's work on internationalization is to ensure that W3C's formats and protocols are usable worldwide in all languages and writing systems.

Establishing trust in the new medium of the Web involves both social and technical issues. Trust is established through a complex and ill-understood social mechanism including relationships, social norms, laws, regulations, traditions, and track records. There is a core of technical issues that are required in any system that is to be trusted:

• The ability to make statements that have agreed-upon meanings. The W3C Metadata Activity provides a means to create machine-readable statements.

• The ability to know who made the statement and to be assured that the statement is really theirs. The W3C Digital Signature Initiative provides a mechanism for signing metadata in order to establish who is making the machine-readable statement.

• The ability to establish rules that permit actions to be taken, based on the statements and a relationship to those who made the statements. The Platform for Internet Content

Selection (PICS) rules specification allows rules to be written down so that they can be understood by machines and exchanged by users.

• The ability to negotiate binding terms and conditions. The Joint Electronic Payment Initiative (JEPI) project created the Protocol Extension Protocol (PEP) to provide for negotiation on the Web. Negotiation is also at the core of the Platform for Privacy Preferences Project (P3P).

• Electronic commerce markup and payment: The W3C has two working groups in this field, on markup for electronic commerce and for payment initiation.

The WAP Forum's exclusive focus is mobile wireless technologies. The goal of WAP is to create recommendations and specifications that support the creation of advanced services on wireless devices with particular emphasis on the mobile telephone. The WAP Forum is creating recommendations and technologies, which enable these services on all mobile devices and on all networks.

The WAP Forum has undertaken a variety of technical specification work relevant to the W3C/WAP Forum collaborative efforts. All these efforts relate to the use of World Wide Web technology on mobile devices, and in ensuring that the quality of these services is sufficient for mass deployment.

WAP is focused on enabling the interconnection of the Web and WTs. Significant focus has been given to mobile telephones and pagers, but all technology has been developed with broader applicability in mind. The goal of WAP is to enable an extremely wide range of WTs that range from mass-market mobile telephones and pagers to more powerful devices to enjoy the benefits of Web technology and interconnection.

Mobile devices have a unique set of features, which must be exposed in the Web, in order to enable the creation of advanced telephony services, and include

• location-based services;

• intelligent network functionality, including integration into the voice network;

• voice/data integration.

The WAP Forum is working to increase the bandwidth efficiency of Web technology to make it more applicable to the wireless environment. WAP Forum work includes the following:

• Smart Web proxies - proxies capable of performing intelligent transformation of protocols and content, enabling more efficient use of the network, adaptation to device characteristics, and adaptation to network characteristics.

• Efficient content encoding - bandwidth efficient encodings of standard Web data formats such as XML.

• Efficient protocols - bandwidth efficient adaptations of standard Web protocols such as HTTP.

The WAP Forum is working to improve the behavior of Web technology due to high network latencies, and in particular, is focusing on the problems of

• tuning network protocols to be adaptive and efficient given wide ranging latencies;

• creating Web applications that are resilient to either high latency environments or highly variable latency situations.

WAP Forum work in this area includes the following:

• User agent state management

• Protocol design (e.g., session state, fast session resumption, etc.).

Mobile wireless devices are characterized by a different set of user interface constraints than a personal computer. The WAP Forum work in this area includes the following:

• Content adaptation - mechanisms allowing a Web application to adapt gracefully to the characteristics of the device (beyond the HTTP/1.1 content negotiation model).

• User interface scalability content formats - for example, markup and display languages that are suitable to impoverished devices, but which scale well to more sophisticated devices.

In the area of Web technologies, the focus of the WAP Forum and the W3C directly overlaps in the areas of intelligent proxies and protocol design, in XML applications, and in content adaptation, for example, through the use of vector graphics and style sheets. The cooperation may also occur in the area of electronic payment in which the work of both groups has the potential to overlap.

Instead of developing diverging solutions, it is the intent of both groups to find common solutions that will address mobile requirements. In the area of Web technology, the goals overlap, especially in the long run, allowing significant cooperation and shared development. To avoid fragmentation of the Web standards, the groups cooperate and focus on achieving the seamless integration of mobile devices into the Web.

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