Wireless Application Protocol WAP. F. Ricci 2008/2009

Transcription

1 Wireless Application Protocol WAP F. Ricci 2008/2009

2 Content Web and mobility Problems of HTML in the mobile context Wap 1.x Motivations Features Architecture Examples of WML (Wireless Markup Language) pages Wap 2.0 XHTML MP Examples Differences with Wap 1.x

3 Examples

4 World Wide Web and mobility Protocol (HTTP, Hypertext Transfer Protocol) and language (HTML, Hypertext Markup Language) of the Web have not been designed for mobile applications and mobile devices, thus creating many problems! Typical transfer sizes HTTP request: byte responses avg. <10 kbyte, header 160 byte, GIF 4.1kByte, JPEG 12.8 kbyte, HTML 5.6 kbyte but also many large files that cannot be ignored The Web is not a file system Web pages are not simple files to download static and dynamic content, interaction with servers via forms, content transformation, push technologies etc. many hyperlinks, automatic loading and reloading, redirecting a single click might have big consequences!

5 HTML and mobile devices HTML designed for computers with high performance, color high-resolution display, mouse, hard disk typically, web pages optimized for design, not for communication Mobile devices often only small, low-resolution displays, very limited input interfaces (small touch-pads, soft-keyboards) Additional features animated GIF, Java AWT, Frames, ActiveX Controls, Shockwave, movie clips, audio,... many web pages assume true color, multimedia support, high-resolution and many plug-ins Web pages ignore the heterogeneity of end-systems! e.g., without additional mechanisms, large highresolution pictures would be transferred to a mobile phone with a low-resolution display causing high costs.

6 HTTP 1.0 and mobility Characteristics stateless, client/server, request/response needs a connection oriented protocol (TCP), one connection per request (some enhancements in HTTP 1.1) primitive caching and security Problems designed for large bandwidth (compared to wireless access) and low delay big and redundant protocol headers (readable for humans, stateless, therefore big headers in ASCII) uncompressed content transfer using TCP huge overhead per request (3-way-handshake) compared with the content, e.g., of a GET request slow-start problematic DNS lookup by client causes additional traffic.

7 WAP Programming Model Aligned with the Web Programming Model, uses the Pull Model Add telephony support with WTA (Wireless Telephony Application) and enabling a Push Model, where a server can proactively send content to the client.

8 WAP optional Proxy Model In WAP1.* ( ) a WAP proxy (in the middle) was used (still required for push)

9 WAP - Wireless Application Protocol Goals deliver Internet content and enhanced services to mobile devices and users (mobile phones, PDAs) independence from wireless network standards open for everyone to participate, protocol specifications will be proposed to standardization bodies applications should scale well beyond current transport media and device types and should also be applicable to future developments Platforms e.g., GSM (900, 1800, 1900), CDMA IS-95, TDMA IS-136, 3rd generation systems (IMT-2000, UMTS, W-CDMA, cdma2000 1x EV-DO, ) Forum was: WAP Forum, co-founded by Ericsson, Motorola, Nokia, Unwired Planet, further information now: Open Mobile Alliance (Open Mobile Architecture + WAP Forum + SyncML + )

10 WAP - scope of standardization Browser micro browser, similar to existing, well-known browsers in the Internet Script language similar to Java script, adapted to the mobile environment WTA/WTAI Wireless Telephony Application (Interface): access to all telephone functions Content formats e.g., business cards (vcard), calendar events (vcalender) Protocol layers transport layer, security layer, session layer etc.

11 WAP Push This service allows content to be sent or "pushed" to devices by server-based applications via a Push Proxy WAP Push messages are specially formatted SMS messages that display an alert message to the user, and give the user the option of connecting directly to a particular URL via the mobile phone's WAP browser Push functionality is especially relevant to real-time applications e.g. that send notifications as messaging, stock price and traffic update alerts Without push, these applications would require the devices to poll application servers for new information or status In wireless environments such polling activities would constitute inefficient and wasteful use of the resources of wireless networks.

12 WAP 1.x - reference model and protocols Internet HTML, Java HTTP SSL/TLS A-SAP WAP Application Layer (WAE) S-SAP Session Layer (WSP) TR-SAP Transaction Layer (WTP) SEC-SAP Security Layer (WTLS) T-SAP additional services and applications TCP/IP, UDP/IP, media Transport Layer (WDP) Bearers (GSM, CDPD,...) WCMP WAE comprises WML (Wireless Markup Language), WML Script, WTAI etc.

13 WAP - network elements fixed network wireless network Internet HTML filter WML WAP proxy Binary WML HTML web server HTML WML HTML filter/ WAP proxy Binary WML PSTN WTA server Binary WML Binary WML: binary file format for clients

14 WAE - Wireless Application Environment Goals network independent application environment for lowbandwidth, wireless devices integrated Internet/WWW programming model with high interoperability Requirements device and network independent, international support manufacturers can determine look-and-feel, user interface considerations of slow links, limited memory, low computing power, small display, simple user interface (compared to desktop computers) Components architecture: application model, browser, gateway, server WML: XML-Syntax, based on card stacks, variables,... WMLScript: procedural, loops, conditions,... (similar to JavaScript) WTA: telephone services, such as call control, text messages, phone book,... (accessible from WML/WMLScript) content formats: vcard, vcalendar, Wireless Bitmap, WML,...

15 Wireless Markup Language (WML) WML follows deck and card metaphor WML document consists of many cards, cards are grouped to decks a deck is similar to an HTML page, unit of content transmission WML describes only intent of interaction in an abstract manner presentation depends on device capabilities Features text and images user interaction navigation context management

16 Hello World (WML) <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" " <wml> <card id="card1" title="wml Tutorial"> <p>hello World</p> </card> <card id="card2" title="wml Tutorial"> <p>welcome to the world of WML</p> </card> </wml> /wml/helloworldeg1.wml

17 Fonts <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" " <wml> <card id="card1" title="font Style"> <p> <b>bold</b><br/> <i>italic</i><br/> <u>underline</u><br/> <small>small</small><br/> <big>big</big><br/> <em>emphasis</em><br/> <strong>strong</strong> </p> </card> </wml>

18 Tables <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" " <wml> <card id="page1" title="table in WML"> <p> <table columns="3"> <tr> <td>cell A</td> <td>cell B</td> <td>cell C</td> </tr> <tr> <td>cell D</td> <td>cell E</td> <td>cell F</td> </tr> </table> </p> </card> </wml>

19 Links wml page/deck <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" " <wml> wml card <card id="tutorial_tc" title="wml Tutorial"> <p> Hello, welcome to our WML tutorial.<br/><br/> Table of Contents:<br/> <anchor> <go href="linkseg2.wml#tutorial_ch1"/> Chapter 1: WML Introduction </anchor><br/> <anchor> <go href="linkseg2.wml#tutorial_ch2"/> Chapter 2: WML Deck and Card </anchor><br/> <anchor> <go href="linkseg2.wml#tutorial_ch3"/> Chapter 3: WML Document Structure </anchor><br/> <anchor> <go href="linkseg2.wml#tutorial_ch4"/> Chapter 4: WML Generic Metadata </anchor><br/> </p> </card> </wml>

20 Going to a Card in the Deck <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" " <wml> <card id="tutorial_ch1" title="wml Tutorial Ch1"> <p> <em>chapter 1: WML Introduction</em><br/><br/>...<br/><br/> <anchor> <go href="#tutorial_ch2"/> Next chapter: WML Deck and Card </anchor> </p> </card> <card id="tutorial_ch4" title="wml Tutorial Ch4"> <p> <em>chapter 4: WML Generic Metadata</em><br/><br/>...<br/><br/> <anchor> <go href="#tutorial_ch1"/> Back to chapter 1: WML Introduction </anchor> </p> </card> </wml>

21 Input <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" " <wml> <card id="card1" title="wml Input Fields"> <p> Hello, welcome to our WML tutorial.<br/> What's your name? <input name="myname" maxlength="16"/> </p> </card> </wml>

22 Events and Variables <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" " <wml> <card id="card1" title="wml Variable"> <onevent type="onenterforward"> <refresh> <setvar name="var1" value="variable 1"/> </refresh> </onevent> <p> What's your name? <input name="name" maxlength="16"/><br/> Variable declaration and initialization Variable assignment Variable declaration Which part of our WML tutorial do you like? <select name="tutorial_part"> <option value="part 1">Part 1</option> <option value="part 2">Part 2</option> <option value="part 3">Part 3</option> </select><br/><br/> <a href="#card2">next Card</a> </p> </card> <card id="card2" title="wml Variable"> <p> Your name is $(name).<br/><br/> You like $(tutorial_part) of our WML tutorial.<br/><br/> The value of var1 is <i>$(var1)</i>. </p> </card> </wml>

23 WMLScript Complement to WML Provides general scripting capabilities Features validity check of user input check input before sent to server access to device facilities hardware and software (phone call, address book etc.) local user interaction interaction without round-trip delay extensions to the device software configure device, download new functionality after deployment

24 WMLScript - example function pizza_test(pizza_type) { var taste = "unknown"; if (pizza_type = "Margherita") { taste = "well... "; } else { if (pizza_type = "Vulcano") { taste = "quite hot"; }; }; return taste; };

25 Wireless Telephony Application (WTA) Collection of telephony specific extensions Extension of basic WAE application model content push server can push content to the client handling of network events client side there is a table indicating how to react on certain events from the network access to telephony functions any application on the client may access telephony functions Example calling a number (WML) wtai://wp/mc; calling a number (WMLScript) WTAPublic.makeCall(" ");

26 WTAI - example with WML only <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" " <wml> <card id="card_one" title="tele voting"> <do type="accept"> <go href="#card_two"/> </do> <p> Please choose your candidate! </p> </card> <card id="card_two" title="your selection"> <do type="accept"> <go href="wtai://wp/mc;$dialno"/> </do> <p> Your selection: <select name="dialno"> <option value=" ">mickey</option> <option value=" ">donald</option> <option value=" ">pluto</option> </select> </p> </card> </wml> associate to the "accept" button the action to go to href="#card_two" associate to the "accept" button the action to dial dialno

27 WAP 2.0 (July 2001) XHTML MP (XHTML Mobile Profile) is the markup language of WAP 2.0. XHTML MP is a subset of XHTML (XHTML Basic + specific add-ons) In addition to the WAP stack, adds a stack based on common Internet stack based on TCP, TLS and HTTP (with Wireless Profile ) New applications Color graphics Animation Large file download Location based services Synchronization with PIMs Pop-up/context sensitive menus Goal: integration of WWW, Internet, WAP, i-mode

28 Hello World in WAP 2 <?xml version="1.0"?> <!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.0//EN" " <html xmlns=" <head> <title>xhtml MP Tutorial</title> </head> <body> <p>hello world. Welcome to our XHTML MP tutorial.</p> </body> </html>

29 Advantages of WAP 2 If you are familiar with web technologies such as HTML, XHTML, and CSS, you can start developing your WAP site almost immediately The same development tools can be used to develop both web sites and WAP sites Ordinary web browsers can be used to view your WAP site during the development process HTML / XHTML pages on your web site can be converted to XHTML MP documents with minor changes or even without any changes XHTML MP supports WAP CSS, which enables the separation of content and presentation in different files With XHTML MP and WAP CSS, you have more control over the presentation: e.g., you can control borders, backgrounds, margins, padding, font sizes, font families and font colours.

30 WAP 2.0 Enhancements User Agent Profile (UAProf) This service provides a mechanism for describing the capabilities of clients and the preferences of users to an application server Based on the Composite Capabilities / Preference Profiles (CC/PP) work of the W3C, UAProf supports the client-server transaction model by sending client and user information to servers with the request This information permits the servers to adapt their content accordingly in preparation for the response Recognizing the importance of user's privacy, personal information submitted in these requests may be controlled by the user Data Synchronization The SyncML messages are supported over both the WSP (Wireless Session Protocol) and HTTP/1.1 protocols.

31 UAProf UAProf (User agent profile) is an XML document that contains information about the user agent type and device capabilities User agent profiles are stored in a server called the profile repository (often maintained by a mobile device manufacturer) The URL that points to the user agent profile of a mobile device can be found in the headers of requests sent by the mobile device: x-wap-profile header Example, the UAProf of Nokia N95 8Giga:

32 WML Features Lost in XHTML MP XHTML MP does not support decks and cards XHTML MP does not support timers XHTML MP does not support events XHTML MP does not support variables XHTML MP does not support client-side scripting XHTML MP does not support programmable softkeys XHTML MP does not support the format attribute for input fields (to restrict the input type) XHTML MP does not support posting of data with anchor links (it uses forms)