Introduction
The following sections provide information that you need to know before using the BEA WebLogic Server platform to extend Web applications to wireless subscribers:
- Overview
- Wireless Data Protocols
- The WAP Protocol at a Glance
- The i-Mode Protocol at a Glance
- Other Wireless Data Protocols
- Other Wireless Markup Languages
- Evolution of Wireless Data Protocols and Wireless Markup Languages
- Additional Information
Overview
The wireless Internet-enabled subscriber base continues to grow. Telecommunications companies and wireless service providers are looking for ways to rapidly create and deploy new revenue-generating Internet services while providing their wireless subscribers with a more personalized experience.
Because wireless subscribers have a different set of essential desires and needs than desktop or even laptop Internet users, Internet services must be designed to present the optimum experience for subscribers using different types of wireless devices. Writing Internet services in this manner requires a deep understanding of the technical issues unique to the wireless environment.
Wireless Data Protocols
Using Internet technologies such as Hypertext Transfer Protocol (HTTP), Transport-Layer Security (TLS), Transmission Control Protocol (TCP), and Hypertext Markup Language (HTML) to set up and tear down connections and to transport Web content on a wireless network is inefficient for several reasons, including:
- HTTP and TCP are not optimized for the intermittent coverage, long latencies, and limited shared bandwidth associated with wireless networks.
- HTTP sends its headers and commands in a text format, which is not well suited for the low-bandwidth constraints of wireless networks, instead of the more efficient compressed binary format.
- HTTP session setup and teardown require many messages to be exchanged between the wireless device (client) and the server.
- HTML Web content intended for the desktop browser cannot be displayed in an effective way on the small-size screens of handheld mobile phones, personal digital assistants (PDAs), pagers, two-way radios, and smartphones.
- Navigation around and between screens is not easy due to no keyboard and no mouse; navigation is accomplished by pressing numeric keys or writing with a stylus.
Wireless services using these protocols are often slow, costly, and difficult to use, which is why special wireless data protocols were created to transport Web-based data on a wireless network. Wireless data protocols, such as Wireless Application Protocol (WAP), i-Mode, and others, are designed for the unique constraints of the wireless environment. They use binary transmission for greater compression of data and are optimized for long latency and low to medium bandwidth. They support protocol data unit (PDU) concatenation and delayed acknowledgement to help reduce the number of messages sent. Their associated markup languages make optimum use of small screens and allow easy navigation around and between screens.
To read the markup language associated with a wireless data protocol, a wireless device requires a microbrowser, which is client software specially designed to interpret the markup language. As examples, a WAP-enabled device has a Wireless Markup Language (WML) microbrowser, and an i-Mode-enabled device has a compact HTML (cHTML) microbrowser.
The WAP Protocol at a Glance
The Wireless Application Protocol (WAP) specification consists of a wireless data protocol - a standardized way that the microbrowser on a wireless device communicates with a WAP gateway installed in the wireless network - and a markup language, Wireless Markup Language (WML). WML is an Extensible Markup Language (XML) used to specify the content and user interface for WAP-enabled devices.
WAP sessions cope with intermittent coverage and can operate over a wide variety of wireless bearer networks including but not limited to Cellular Digital Packet Data (CDPD), Code Division Multiple Access (CDMA), Global System for Mobiles (GSM), Time Division Multiple Access (TDMA), and General Packet Radio Service (GPRS). Although most WAP services in Europe and the United states are circuit-switched (dial-up), WAP will also work on packet-switched networks.
The i-Mode Protocol at a Glance
The i-Mode specification consists of a wireless data protocol - a standardized way that the microbrowser on a wireless device communicates with an i-Mode gateway installed in the wireless network - and a markup language, compact HTML (cHTML). cHTML is a subset of HTML with extensions and is used to specify the content and user interface for i-Mode-enabled devices.
Note: In publications, i-Mode appears in many different forms including i-Mode, I-Mode, I-mode, i-mode, and imode. i-Mode is used throughout this discussion and the discussions that follow.
While WAP is an open, global specification, i-Mode is currently a proprietary, closed specification developed and deployed by NTT DoCoMo of Japan. The only i-Mode implementation is NTT DoCoMo's mobile internet access system, although several telecommunication companies in Europe and the United States have expressed an interest in i-Mode.
Although i-Mode currently operates only on NTT-DoCoMo's PDC-P mobile voice system, i-Mode will work equally well on any underlying wireless bearer network.
Other Wireless Data Protocols
Other wireless data protocols include:
- Handheld Device Transport Protocol (HDTP) developed by Phone.com (formerly Unwired Planet and now Openwave Systems Inc.)
- Mobitex developed by the Mobitex Operators Association
The wireless industry is also very interested in the Voice over IP (VoIP) technology, which moves voice and data traffic over a common IP infrastructure. The wireless industry is looking for ways to converge the VoIP and wireless data protocol technologies so that voice and Web data can be carried on the same over-the-air channel.
Other Wireless Markup Languages
Other wireless markup languages include:
- Handheld Device Markup Language (HDML) developed by Phone.com (formerly Unwired Planet and now Openwave Systems Inc.)
- Web Clipping developed by Palm, Inc.
- Extensible HTML (XHTML) (Basic) developed by the World Wide Web Consortium (W3C)
- VoiceXML developed by the VoiceXML Forum, an industry organization founded by AT&T, IBM, Lucent, and Motorola
Note: HDTP carries Web content tagged with HDML. HDTP and HDML heavily influenced the development of WAP and WML.
Evolution of Wireless Data Protocols and Wireless Markup Languages
The various wireless data protocols and wireless markup languages in existence today may very well evolve into a single wireless data protocol and wireless markup language tomorrow. As evidence, proponents of the WAP protocol are about to migrate to a new generation of the protocol known as WAP-NG, and both AT&T an NTT DoCoMo have made allegiances to WAP-NG. In addition, proponents of WAP and i-Mode are talking about migrating to the common markup language XHTML (Basic).
Additional Information
Here are some Web sites (organized by category) to visit for additional information about wireless data protocols, wireless markup languages, manufacturers of wireless devices, and wireless standards and specifications.
Related WebLogic Wireless Information
BEA-written white paper titled "Beyond the Wire - Developing Software for Many Devices"
General Wireless Information
Wireless-Device Manufacturers
Wireless Standards and Specifications
XHTML Basic W3C Recommendation
The Short Message Peer to Peer (SMPP) Forum
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