Điện thoại di động giao thức viễn thông cho các mạng dữ liệu P6

Network architecture supporting wireless applicationsThe Wireless Application Environment (WAE) architecture is designed to support Mobile Terminals (MTs) and network applications using different languages and character sets. WAE user agents have a current language and accept content in a set of well-known character encoding sets. Origin server-side applications can emit content in one or more encoding sets and can accept input from the user agent in one or more encoding sets. Wireless Telephony Application (WTA) is an application framework for telephony services....
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Điện thoại di động giao thức viễn thông cho các mạng dữ liệu P6 Mobile Telecommunications Protocols For Data Networks. Anna Ha´ c Copyright  2003 John Wiley & Sons, Ltd. ISBN: 0-470-85056-6 6 Network architecture supporting wireless applicationsThe Wireless Application Environment (WAE) architecture is designed to support MobileTerminals (MTs) and network applications using different languages and character sets.WAE user agents have a current language and accept content in a set of well-knowncharacter encoding sets. Origin server-side applications can emit content in one or moreencoding sets and can accept input from the user agent in one or more encoding sets. Wireless Telephony Application (WTA) is an application framework for telephony ser-vices. The WTA user agent has the capability for interfacing with mobile network servicesavailable to a mobile telephony device, that is, setting up and receiving phone calls. The Wireless Application Protocol (WAP) Push framework introduces a means withinthe WAP effort to transmit information to a device without a previous user action. Inthe client/server model, a client requests a service or information from a server, whichtransmits information to the client. In this pull technology, the client pulls informationfrom the server.6.1 WAE ARCHITECTUREThe WAE architecture includes networking schemes, content formats, programming lan-guages, and shared services. Interfaces are not standardized and are specific to a particularimplementation. WAE can work with a browser and a class of user agents used in theWorld Wide Web (WWW). In the Internet WWW, applications present content to a client in a set of standarddata formats that are browsed by client side user agents known as Web browsers. A useragent sends requests for one or more data objects or content to an origin server, whichresponds with the requested data expressed in one of the standard formats known tothe user agent [i.e., Hypertext Markup Language (HTML)]. The WWW logical model isshown in Figure 6.1.94 NETWORK ARCHITECTURE SUPPORTING WIRELESS APPLICATIONS Origin server Client Request (URL) CGI scripts, etc. User agent Content Response (content) Figure 6.1 WWW logical model. Gateway Origin server Client Encoded request Request CGI scripts, etc. WAE Encoders user and agent decoders Content Encoded response Response (content) Figure 6.2 WAE logical model. All resources on the WWW are named using Internet standard Uniform Resource Loca-tors (URLs). All classes of data on the WWW are given as specific types, allowing theuser agent to correctly distinguish and present them appropriately. The WWW definesa variety of standard content formats supported by most browser user agents, includingthe HTML, the JavaScript scripting language, and other formats like bitmap image for-mats. The WWW defines a set of standard networking protocols allowing any browser tocommunicate with any origin server, for example, Hypertext Transfer Protocol (HTTP). The WAE logical model is shown in Figure 6.2. In the WAE model, the content istransported using standard protocols in the WWW domain and an optimized HTTP-like protocol in the wireless domain. The content and services in WAE architecture arehosted on standard Web origin servers using proven technologies like Common GatewayInterface (CGI). The content is located by using WWW standard URLs. WAE supportsWAE ARCHITECTURE 95Mobile Network Services such as Call Control and Messaging. WAE architecture supportslow bandwidth and high latency networks and considers CPU processing constraints inMTs. WAE assumes the existence of gateway functionality responsible for encoding anddecoding data transferred from and to the mobile client. The purpose of the encodingcontent delivered to the client is to minimize the size of data sent to the client OverThe Air (OTA), and to minimize the computational energy required by the client toprocess the data. The gateway functionality can be added to origin servers or placed indedicated gateways. The main elements of the WAE model are WAE user agents, content generators,standard content encoding, and WTA. WAE user agents interpret network content ref-erenced by a URL. Content generators are the applications or services on origin server ...