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    Rapid and Expressive Prototyping on Cell Phones via Script ... Rapid and Expressive Prototyping on Cell Phones via Script ... Presentation Transcript

    • Rapid and Expressive Prototyping on Cell Phones via Script Embedding Jingtao Wang Computer Science Division [email_address]
    • Agenda
      • Motivation
      • Challenges in creating cell phone app
      • Overview of popular mobile development platforms
      • Low threshold and high ceiling, the script embedding approach
      • Summary
    • The Popularization of Cell Phones
    • Cell Phone is THE Portable Computing Device
      • Global penetration reached 50% (3.3 Billion) on 11/29/2007
      • 59 countries had cell phone market share over 100%
        • Luxembourg 158%
        • Hong Kong 140%
        • Italy 122%
        • United States 81%
        • China ~ 42%
        • India 23% (largest growth market)
      • There are only around 850 million PCs in the world.
      * Data from Informa Telecoms & Media
    • Opportunities and Challenges of Cell Phones
      • The bright side
        • Portable, always with you
        • Always on, always connected to the internet
        • Seamless integration with one’s social networks
        • High market penetration throughout the world
      • The dark side
        • Limited resources (CPU, memory, screen, input modality)
        • Highly diversified hardware and software implementations
        • Incomplete development tools and libraries
        • Proprietary hardware/software decrease competition and add costs in development and distribution
    • Threshold and Ceiling Sophistication (Ceiling) C/C++ Goal HTML Difficulty (Threshold) MFC/Qt Flash ActionScript Component Framework
    • An Overview of Mobile Development Platforms - 1
      • Mainstream (non-smart) Phones (more than 90% market share)
        • J2ME (Java 2 Micro Edition)
        • BREW (Binary Runtime Environment for Wireless)
        • Flash Lite
        • HTML, WAP/WML
    • An Overview of Mobile Development Platforms - 2
      • Smart Phones (less than 10% market share)
        • Windows Mobile ( Embedded Visual C++ , .Net Framework Compact Edition)
        • Linux (C/C++, Java, J2ME)
        • Symbian ( C++ , Python)
        • Palm ( C/C++ , J2ME)
        • Flash Lite
        • BREW
        • HTML/AJAX, WAP/WML
    • J2ME
      • Best availability on different platforms
      • Can leverage knowledge and resources from desktop Java
      • Good debugging support
      • Poor UI framework/libraries
      • Inconsistent behaviors in different devices (write once, debug everywhere)
      • Poor performance (no JIT on most devices)
      • Low ceiling (can only do what the built-in libraries allow one to do)
      • Signature required to access certain functions
    • BREW
      • Using C/C++ as the host language
      • Excellent performance (applications run as compiled native code)
      • Small target application size and little overhead
      • High ceiling (can access all the capabilities of the phone)
      • The only widely available native API for non-smart phones
      • Steep learning curve
      • Bad UI library
      • More costs for the development environments and the development process
      • Hard to debug (different behaviors between the simulator and the real device)
      • Troublesome coding restrictions
      • Signature required to run any applications on a cell phone
    • Flash Lite
      • Flash Lite 2.x similar to Flash 7.0
      • Excellent IDE/Emulator support
      • Powerful functions for animation/vector graphics
      • Low learning threshold
      • Low runtime performance
      • Hard to access functions not provided, low ceiling
      • “ ActionScript Stuck”
    • HTML, WAP/WML
      • Available on almost all cell phones
      • Low learning threshold
      • Easy to debug (functions implemented on the server side)
      • Low ceiling
      • Limited interactivity function support
      • Almost impossible to access local resources of the cell phone
      • High latency, requires network connection
    • Windows Mobile – Embedded Visual C++
      • Excellent performance
      • Intermediate learning curve for existing C/C++ programmers
      • Relatively steep learning curve for non-C/C++ programmers
      • Easy to access hardware features
      • Excellent UI framework and UI builder
      • Excellent IDE/debugger support
      • Excellent emulator support
      • Limited device penetration
    • Windows Mobile – .Net Framework Compact Edition
      • Medium to Good performance
      • Low learning threshold
      • Excellent UI framework and UI builder
      • Excellent IDE/debugger support
      • Excellent emulator support
      • Extra space overhead (2 mb)
      • Limited device penetration
    • Symbian – C++
      • Excellent performance
      • High learning threshold
      • Reasonable UI framework
      • High ceiling
      • High market share among smart phones
      • Poor IDE/debugger support
      • Troublesome coding restrictions
      • Poor simulator support
      • Limited device penetration in the U.S.
    • Symbian – Python
      • Poor performance
      • Low learning threshold
      • Reasonable UI framework
      • Relatively high ceiling
      • Poor IDE/debugger support
      • Poor simulator support
      • Additional runtime overhead (> 1mb)
      • Limited device penetration in the U.S.
    • Palm
      • Huge paradigm shift between version 1.x – 4.x and 5.x +
      • Only device specific simulator after 5.x
      • Gradually becoming obsolete
    • Android and iPhone
      • Android
        • Customized version of Java (between Java desktop and J2ME)
        • Good UI framework (when compared with J2ME)
        • Limited media capture capability as J2ME
        • Calling native functions is discouraged
      • iPhone
        • HTML + AJAX based web app running on browsers
        • Native app (Objective C)
    • Native Code vs. Dynamic Script
      • Native Code
        • Excellent runtime speed
        • High threshold, high ceiling
        • Easy to access the low level hardware
        • Difficult to program and difficult to debug
      • Dynamic (Interpreted) Script
        • Slow runtime speed
        • Easy to learn, low ceiling
        • Easy to debug, easy to share
        • Hard to access extra features of the hardware
      • Can we take advantages of nice things from both approaches?
    • Embedding Scripts to the Host Application Host Program Embedded Interpreter color = RED b = button { label = ‘OK’, x = 10, y = 20} Wrapped Library
    • Choice of the Embedded Script Engine
      • Lua is a powerful, fast, light-weight, embeddable scripting language
        • Originated in 1993, now developed by Lablua
        • Designed as a lightweight embedded script language
        • A leading scripting language in the games industry
        • See www.lua.org
      • Has been ported to BREW, Windows Mobile and Symbian
    • Approximate Runtime Performance
      • Not intended to be a comprehensive evaluation
      • Benchmarking programs (sorting, factorial computing, string operations)
      Vs. Runtime Speed Runtime Memory C/C++ 1/5 ~ 1/12 1.0 ~ 1.5 Python 1.9 ~ 3.5 2.1 ~ 3.3 JavaScript 2.3 ~ 18 1.7 ~ 9.7
    • Some Sample Codes function HelloWorld () io.write (&quot;hello World&quot;) trace (&quot;trace working now&quot;) end HelloWorld() function fat (n) if n == 0 then return 1 else return n*fat(n-1) end end Function max(a, b) local m = a if b > a then m = b end return m end 1 MOVE 2 0 0 ; R(2) = R(0) 2 LT 0 0 1 ; R(0) < R(1) 3 JMP 1 ; to 5 (4+1) 4 MOVE 2 1 0 ; R(2) = R(1) 5 RETURN 2 2 0 ; return R(2) 6 RETURN 0 1 0 ; return
    • Easy to Switch Between both Worlds LIBSHELL_API int LibSHELL_MessageBoxText(lua_State *L) { const char *szTitle = (const char *)luaL_checkudata(L, 1, AECHAR_TNAME); const char *szText = ( const char *)luaL_checkudata(L, 2, AECHAR_TNAME); ISHELL_MessageBoxText(GETAPPSHELL(), szTitle, szText); return 0; } …… lua_register(L, “messageBox&quot;, LibSHELL_MessageBoxText ); Exporting the ISHELL_MessageBoxText function from BREW to the script Void FireEvent(int id, const char * args) { if (g_strEventHandler != NULL) { char buf[254]; SPRINTF( buf, “%s(%d,%s)”, g_strEventHandler, id, args); lua_pcall(luaState, buf, LUA_MULTRET, 0); } return; } Calling a lua function (event handler) from C/C++
    • Scaffolding Mobile Development via Script Embedding
      • Average users
        • Use form-guided code generation templates to customize an application
        • Download and share new functions
      • Group development
        • Only one member responsible for C/C++ programming, expose additional native functions to script programmers via glue function
        • Other members fast prototyping in script
      • Runtime performance sensitive application
        • Identify performance bottlenecks in the script implementation, reemployment them in C/C++ and export them to the script
    • Summary
      • Building applications for cell phones is challenging due to highly diversified environment and toolkits
      • Trade-offs between low learning threshold and high ceiling need to be carefully considered
      • Script embedding is a solution to leverage nice features from both worlds
    • Thanks!
      • Any questions?