Mobile Station Execution Mobile Station Execution Environment (MExE - PowerPoint PPT Presentation

Mobile Station Execution Mobile Station Execution Environment (MExE MExE) ) Environment ( • MExE MExE is a standard for defining various levels of is a standard for defining various levels of • wireless communication wireless communication Developing web applications Developing web applications • These levels are called These levels are called classmarks classmarks • for PDAs PDAs and and Cellphones Cellphones for • Mobile devices can support more than one Mobile devices can support more than one classmark classmark • • Current Defined classmarks include: Current Defined classmarks include: • – Classmark – Classmark 1: Wireless Application Protocol (WAP) 1: Wireless Application Protocol (WAP) – Classmark – Classmark 2: 2: PersonalJava PersonalJava & & JavaPhone JavaPhone (includes (includes classmark classmark 1) 1) – Classmark Classmark 3: J2ME, CLDC & MIDP 3: J2ME, CLDC & MIDP – 2 WAP (Wireless Application WAP (Wireless Application Protocol) Protocol) • What is WAP? What is WAP? • – It is a set of protocols for wireless data It is a set of protocols for wireless data – Classmark 1: WAP 1: WAP Classmark transmission transmission – It strives to be an the equivalent of what the – It strives to be an the equivalent of what the internet is for the wired world internet is for the wired world – Designed to address issues specific to mobile – Designed to address issues specific to mobile commerce commerce 4

Issues WAP Addresses WAP Gateway Issues WAP Addresses WAP Gateway • The WAP gateway provides a solution to the The WAP gateway provides a solution to the • The limitations of wireless communication The limitations of wireless communication • • limitations of the wireless networks limitations of the wireless networks – Intermittent network connectivity Intermittent network connectivity – • Mobile users connect to the gateway and any Mobile users connect to the gateway and any • – Large latency Large latency – communications they request will be passed through communications they request will be passed through • • Providing an easy to uses interface for mobile devices Providing an easy to uses interface for mobile devices the gateway the gateway – The screens are small The screens are small – • It provides a access point to the rest of the web • It provides a access point to the rest of the web – Limited input types – Limited input types • Takes over many Takes over many cpu cpu intensive operations for the intensive operations for the • • Security concerns of transmitting wireless data • Security concerns of transmitting wireless data mobile device mobile device • Limited power and computational resources of • Limited power and computational resources of • Handles encryption and decryption as different (less Handles encryption and decryption as different (less • mobile devices mobile devices strenuous) encryption protocols are used for mobile strenuous) encryption protocols are used for mobile devices devices 5 6 Wireless Application Protocols Wireless Markup Language Wireless Application Protocols Wireless Markup Language • WAP is based on: WAP is based on: • • WML is XML based WML is XML based • – WAE (Wireless Application Environment) WAE (Wireless Application Environment) – – Follows strict xml formatting rules Follows strict xml formatting rules – • WML (Wireless Markup Language) WML (Wireless Markup Language) • • Replaces HTML in the WAP browser Replaces HTML in the WAP browser • • WMLScript WMLScript (the (the javascript javascript equivalent for WML) equivalent for WML) • • WML sites are called decks and are made up WML sites are called decks and are made up • • WTAI/WTA (Wireless Telephony Application • WTAI/WTA (Wireless Telephony Application Interface) Interface) of cards of cards – WSP WSP (Wireless Session Protocol) – (Wireless Session Protocol) • The cards are the pages that the users views • The cards are the pages that the users views – WTP WTP (Wireless Transaction Protocol) – (Wireless Transaction Protocol) – – WTLS (Wireless Transport Layer Security) WTLS (Wireless Transport Layer Security) – WDP WDP (Wireless Datagram Protocol) – (Wireless Datagram Protocol) 7 8

Wireless Markup Language Wireless Markup Language Wireless Markup Language Wireless Markup Language <?xml version="1.0"?> <?xml version="1.0"?> • Variables defined in a one card are accessible Variables defined in a one card are accessible • <!DOCTYPE wml <!DOCTYPE wml PUBLIC " PUBLIC "- -//WAPFORUM//DTD WML 1.1//EN" //WAPFORUM//DTD WML 1.1//EN" "http://www. "http://www.wapforum wapforum.org/DTD/ .org/DTD/wml wml_1.1.xml"> _1.1.xml"> from all cards from all cards <wml < wml> > • Some other tags: Some other tags: • <card id=card1> ….. </card> <card id=card1> ….. </card> – <! <!-- -->, <head>, <meta>, <template>, < >, <head>, <meta>, <template>, <br br>, <p>, >, <p>, <card id=card2> ….. </card> – <card id=card2> ….. </card> ….. ….. <table>, <td>, <tr tr>, <b>, <big>, < >, <b>, <big>, <em em>, <a>, >, <a>, <table>, <td>, < <card id=card3> ….. </card> <card id=card3> ….. </card> <anchor>, <img img>, <do>, < >, <do>, <onevent onevent>, < >, <postfield postfield>, >, <anchor>, < </ </wml wml> > <go>, <timer>, <input>, <optgroup optgroup>, <option>, >, <option>, • • WML pages have their own DTD WML pages have their own DTD <go>, <timer>, <input>, < <select>, <setvar setvar> > <select>, < • A deck is the WML document A deck is the WML document • – These are not all of the tags but as you can see – These are not all of the tags but as you can see – Enclosed in < Enclosed in <wml wml> . . . </ > . . . </wml wml> > – many are the same as in HTML many are the same as in HTML • A card is the WML document A card is the WML document • – Enclosed in < Enclosed in <wml wml> . . . </ > . . . </wml wml> > – 9 10 WMLScript Wireless Session Protocol WMLScript Wireless Session Protocol • It is a lightweight version of JavaScript It is a lightweight version of JavaScript • Session level protocol Session level protocol • • • Runs client side Runs client side • It is the HTTP equivalent for WAP It is the HTTP equivalent for WAP • • • Is compiled at a WAP gateway and sent to the Is compiled at a WAP gateway and sent to the • WSP is much more efficient than HTTP due to WSP is much more efficient than HTTP due to • • device in byte code the bandwidth constraints of mobile devices device in byte code the bandwidth constraints of mobile devices • • Not embedded in WML document Not embedded in WML document • Uses binary data • Uses binary data vs vs text data text data • Stored in a WMLS file ( Stored in a WMLS file (ie ie script. script.wmls wmls) ) • • Includes Dialogs, Float, Lang, String, URL Includes Dialogs, Float, Lang, String, URL • and WMLBrower WMLBrower function Libraries function Libraries and 11 12

Wireless Transaction Layer Wireless Transaction Layer Wireless Transaction Protocol Wireless Transaction Protocol Security Security • Provides both reliable and unreliable data Provides both reliable and unreliable data • Security layer protocol Security layer protocol • • transport transport • Similar to SSL (Secure Socket Layer) • Similar to SSL (Secure Socket Layer) • • Similar to TCP Similar to TCP • Provides authentication and encryption Provides authentication and encryption • • Built to minimize network traffic and be most Built to minimize network traffic and be most functionality • functionality effective over a wireless link effective over a wireless link • Like SSL it is only used when needed Like SSL it is only used when needed • 13 14 Wireless Datagram Protocol WAP and the rest of the web Wireless Datagram Protocol WAP and the rest of the web • Similar to UDP (User Datagram Protocol) Similar to UDP (User Datagram Protocol) • Fewer that 1% of sites are written in WML Fewer that 1% of sites are written in WML • • • Lowest layer WAP protocol Lowest layer WAP protocol • Google Google has implemented a tool which converts has implemented a tool which converts • • regular HTML websites to WML for WAP regular HTML websites to WML for WAP • Lower layers are normally device dependent Lower layers are normally device dependent • browsers browsers and some common interfaces are PPP (Point- - and some common interfaces are PPP (Point to- -Point Protocol), SMS (Short Messaging Point Protocol), SMS (Short Messaging • This allows WAP users access to the web This allows WAP users access to the web to • Service), and GPRS (General Packet Radio content not specifically designed for mobile Service), and GPRS (General Packet Radio content not specifically designed for mobile System) devices System) devices 15 16