Wireless Application Protocol & Wireless Markup Language
Meng Gan Institute of Telematics University of Karlsruhe
3/11/2001 1 Overview
T Motivation T WAP T WML T Applications T Conclusion
3/11/2001 WAP&WML 2 Motivation
T Advances of mobile communication systems, especically GSM T Phenomenal growth of handy, PDA and other handheld devices T New services required
3/11/2001 WAP&WML 3 Wireless Communication
3/11/2001 WAP&WML 4 M-Commerce
3/11/2001 WAP&WML 5 Applications
3/11/2001 WAP&WML 6 PC + Internet
T High performance PC T Wired Internet connection (V.90 modem, ISDN, xDSL, Ethernet, ...) T Network protocols: TCP/IP + HTTP T Document format: HTML
3/11/2001 WAP&WML 7 Problems with Wireless Networks
T Low bandwidth T High latency and jitter T High transmission error rate T Low connection stability
3/11/2001 WAP&WML 8 Problems with Wireless Terminals (Handy, PDA,...)
T Small screen, limited display capability T One-finger navigation T Limited RAM/ROM T Limited CPU performance T Low battery life
3/11/2001 WAP&WML 9 Solutions
T Internet access via handheld devices was possible before WAP, but the technologies never took off commercially because they used proprietary technologies that didn‘t work across different platforms.
3/11/2001 WAP&WML 10 WAP-Forum
T http://www.wapforum.org T A consortium of hardware, software, service and other wireless-industry vendors T Founded in June 1997
3/11/2001 WAP&WML 11 WAP Overview (I)
T Designed to address small devices‘ technical limitations T Work with a variety of wireless platforms T Offer a scalable, extensible protocol stack T Designed to solve some of the problems caused when small low-powered devices on different platforms try to use low-bandwidth wireless network technology to access services or data-intensive content via the Internet T WAP uses proxy technology to connect wireless technology with the Web.
3/11/2001 WAP&WML 12 WAP Overview (II)
T The WAP system architecture is based on the WWW programming model, yet optimized to suit the characteristics of a mobile network. T WAP is a global multi-layered protocol which is designed to bring Internet contents to “Thin-Client“ devices T Wireless Application Protocol (WAP) is a set of communications protocols that standardise the way that wireless devices can be used for internet-based access
3/11/2001 WAP&WML 13 WAP Overview (III)
T Client/Server approach T Microbrowser in the mobile phone, requiring only limited resources T WAP puts the intelligence in the WAP Gateways
3/11/2001 WAP&WML 14 WAP Service Model
3/11/2001 WAP&WML 15 How It Works
3/11/2001 WAP&WML 16 WAP Network Elements
Fixed Network Mobile Network
WML Binary WML Internet HTML WAP filter proxy
HTML WML HTML filter/ Binary WML WAP web HTML proxy server
WTA Binary WML server PSTN Binary WML: binary file format for clients 3/11/2001 WAP&WML 17 WAP Reference Model
Internet WAP
HTML, Java Application Layer (WAE) additional services and applications HTTP Session Layer (WSP)
Transaction Layer (WTP)
SSL/TLS Security Layer (WTLS)
TCP/IP, Transport Layer (WDP) UCP/IP, media Transport technologies (GSM, CDPD, ...)
WAE comprises WML (Wireless Markup Language), WMLScript, WTAI etc. 3/11/2001 WAP&WML 18 WDP - Wireless Datagram Protocol
T Protocol of the transport layer within the WAP architecture T Uses directly transport mechanisms of different network technologies T Offers a common interface for higher layer protocols T Allows for transparent communication using different transport technologies
T Goals of WDP T Create a worldwide interoperable transport system with the help of WDP adapted to the different underlying technologies T Transmission services such as SMS in GSM might change, new services can replace the old ones
3/11/2001 WAP&WML 19 WTLS - Wireless Transport Layer Security
T Goals T Data integrity T prevention of changes in data T Privacy T prevention of tapping T Authentication T creation of authenticated relations between a mobile device and a server T Protection against denial-of-service attacks T protection against repetition of data and unverified data
T WTLS T Based on the TLS (Transport Layer Security) protocol (former SSL, Secure Sockets Layer) T Optimized for low-bandwidth communication channels 3/11/2001 WAP&WML 20 WTP - Wireless Transaction Protocol
T Common interface to transport mechanisms, port-based abstract interface to applications T Application is independent of transport mechanisms T Support of different communication scenarios T Connection oriented (WTP/C): reliable, full-duplex, QoS negotiation, flow control, message oriented T Transaction oriented (WTP/T): reliable, data already in the first packet, flow control T Connectionless (WTP/D): unreliable, ca be UDP if IP used for layer 3 T Supports peer-to-peer, client/server and multicast applications T Low memory requirements, suited to simple devices (< 10kbyte ) T Efficient for wireless transmission T Segmentation/reassembly T Selective retransmission T Header compression T Optimized connection setup (setup with data transfer)
3/11/2001 WAP&WML 21 WSP - Wireless Session Protocol
T HTTP 1.1 functionality
T Request/reply, content type negotiation, ... T support of client/server, transactions, push technology T key management, authentication, Internet security services T session management (interruption, resume,...)
3/11/2001 WAP&WML 22 WAE - Wireless Application Environment
T Goals T Network independent application environment for low-bandwidth, wireless devices T Integrated Internet/WWW programming model with high interoperability T Requirements T Device and network independent, international support T Manufacturers can determine look-and-feel, user interface T Considerations of slow links, limited memory, low computing power, small display, simple user interface (compared to desktop computers) T Components T Architecture: application model, browser, gateway, server T WML: XML-Syntax, based on card stacks, variables, ... T WMLScript: procedural, loops, conditions, ... (similar to JavaScript) T WTA: telephone services, such as call control, text messages, phone book, ... (accessible from WML/WMLScript) T Content formats: vCard, vCalendar, Wireless Bitmap, WML, ...
3/11/2001 WAP&WML 23 Examples for WAP protocol stacks
WAE user agent WAP standardization
WAE outside WAP
transaction based WSP application datagram based WTP WTP application WTLS WTLS WTLS
UDP WDP UDP WDP UDP WDP
IP non IP IP non IP IP non IP (GPRS, ...) (SMS, ...) (GPRS, ...) (SMS, ...) (GPRS, ...) (SMS, ...) typical WAP pure data application application with with/without complete protocol additional security stack 3/11/2001 WAP&WML 24 Network Example #1 WAP Gateway
3/11/2001 WAP&WML 25 Network Example #2 WAP Application Server
3/11/2001 WAP&WML 26 Payload vs. Overhead
3/11/2001 WAP&WML 27 HTML and mobile devices
T HTML T designed for computers with “high” performance, color high-resolution display, mouse, hard disk T typically, web pages optimized for design, not for communication T Mobile devices T often only small, low-resolution displays, very limited input interfaces (small touch-pads, soft-keyboards) T Additional “features” T animated GIF, Java AWT, Frames, ActiveX Controls, Shockwave, movie clips, audio, ... T many web pages assume true color, multimedia support, high-resolution and many plug-ins
T Web pages ignore the heterogeneity of end-systems! T e.g., without additional mechanisms, large high-resolution pictures would be transferred to a mobile phone with a low-resolution display causing high costs
3/11/2001 WAP&WML 28 WML/WMLScript
T Wireless Markup Language T Based on XML T WML enables small and flexible information display on mobile phones or PDAs T WML permits scale of display T WMLScript is based on ECMAScript
3/11/2001 WAP&WML 29 WML (I)
T Tag-based browsing language T Screen management (text, images) T Data input (text, selection lists, etc.) T Hyperlinks and navigation support T W3C XML-based language T Inherits technology from HDML and HTML
3/11/2001 WAP&WML 30 WML (II)
T Card metaphor T User interactions are split into cards T Navigation occurs between cards T Explicit inter-card navigation model T Hyperlinks T UI event handling T History T State management and variables T Reduce network traffic T Results in better caching
3/11/2001 WAP&WML 31 WML Example (I)
Thisisanimage in a paragraph
3/11/2001 WAP&WML 32 WML Example (II)
You selected: $(name)
T WMLScript is the scripting language used in WML pages T WMLScript is a light version of the JavaScript language T WML scripts are not embedded in the WML pages. WML pages only contains references to script URLs T WMLScript is compiled into byte code on the server before it is sent to the WAP browser T WMLScript is a part of the WAP specification
3/11/2001 WAP&WML 34 WMLScript Example
{ } Enter a URL:
3/11/2001 WAP&WML 35 Contents Provision
3/11/2001 WAP&WML 36 Implementation
T Nokia Activ Software Suite T Phone.com UP.Link Server T Kannel T http://www.kannel.org T Open Source Project
3/11/2001 WAP&WML 37 Test WAP on PC
T Virtual WAPJAG T http://virtual.wapjag.com T http://virtual.wapjag.com/?url=wap.n- tv.de
3/11/2001 WAP&WML 38 Useful WAP sites:
T WAP sites catalog T http://www.wap.de/Katalog/index.html T News T wap.n-tv.de T wap.tagesschau.de T Information T wap.lufthansa.de T wap.bahn.de T Search engine T wap.fireball.de
3/11/2001 WAP&WML 39 Possible Applications
T M-commerce - shopping, tickets, micro-payments T Finance - statements, funds transfer, shares trading T M-billing - notification, presentation and payment of bills T Enterprise access - inventory, shipment/sales updates, email T M-care - customer service, payment status, account updates T Entertainment - games, gambling, interactive multi-player events T Messaging - communication and collaboration T Travel - scheduling, advisories, reservations T Location services - traffic reports, parking information, store discounts, event recommendations
3/11/2001 WAP&WML 40 Consumer Applications
T Simple Person to T Prepayment Person Messaging T Ringtones T Voice and Fax Mail T Mobile Commerce Notifications T Affinity Programs T Unified Messaging T Mobile Banking T Internet Email T Chat T Information Services
3/11/2001 WAP&WML 41 Corporate Applications
T Job Dispatch T File Transfer T Remote Point Of Sale T Web Browsing T Customer Service T Document Sharing T Remote Monitoring T Collaborative Working Such As Meter Reading T Audio T Vehicle Positioning T Still Images T Corporate Email T Moving Images T Remote LAN Access T Home Automation
3/11/2001 WAP&WML 42 WAP 2.0 - the Next Generation
T XHTML (with backwards compatibility to WML) T TCP T Color graphics T Animation T Large file downloading T Location-smart services T Streaming media T Data synchronization with desktop PIM
3/11/2001 WAP&WML 43 But, What is Actually WAP
T Where are the phones T Wasn‘t actually possible T Challenges T Will it offer appealing content T Will it be obsolete by other technologies T What happens if „Thin-Client“ becomes more powerful T What happens if more bandwidths are available
3/11/2001 WAP&WML 44