1. New Directions in Programming Languages Programming for Mobile Devices

2. Language Evolution Programming languages evolved starting with machine language, through assembler, then to high level languages with the help of compilers. High level languages evolved to have richer features and greater support for abstraction. Basic paradigm was still: source code is compiled to produce executable for a particular machine architecture.

4. Compiled Languages Traditional way of creating programs –Write code for a particular execution environment (device plus options, e.g., graphics cards etc) –Compile code –Link the object code to create executable –Execute the code on the device for which it was written Produce different versions of the code for different device environments. PROBLEM: explosion of different device types and architectures.

6. Compiled Language Problem Very expensive and time consuming to produce many different versions of the program code Very difficult to maintain so many different versions. Different execution environments end up with different versions – confuses the heck out of users!! Execution environments keep evolving at a fast pace, so porting, maintaining and upgrading is a continual, expensive activity.

7. New Programming Environments Laptops – mouse works different, display needs vary PDA’s – mouse? What mouse?, limited display, keyboard? Cell phones!! Differences in memory, input, display/output

8. Desktop vs Mobile Compute power and memory –High versus low Display –Large versus small –Full color versus mostly monochrome Secondary storage –Plenty versus virtually non-existent Power –Unlimited (connected) versus (battery) in hours

9. Desktop vs Mobile Connectivity Connected/Well-connected drops to “often” Plenty bandwidth versus tiny Relatively stable bandwidth versus wildly fluctuating User Interface –Standard versus varying Standards –Almost there versus many

10. Mobile Device Memory Typically, combination of SRAM and Flash RAM is used –Frequently changing data is kept in SRAM. Dell Axim X5 –32 MB SDRAM –32 MB StrataFlash ROM Palm Tungsten –8MB Flash –16MB SDRAM

11. Input Very dependent on user environment –Keypads, buttons and touch pads require larger devices –Touch screens allow smaller devices but can be fragile Interesting touch screen and keypad combinations have been developed Simulate keypad on touch screen –Speech input allows small devices but ambient noise is an issue

12. Input Buttons, softkeys, on-screen keys Directional Keypads Roller Wheels Rocker Controls Most devices have two or four directional arrow buttons. Some use discreet buttons while others use floating pads

13. Wheels and Dials Scroll through menu options and push to activate a selection Some can be used in a single handed operation! Many different variants are available JogDial from Sony - A dial used on mobile end- user devices to scroll through menus and select functions with one hand. Also known as Thumb Dial

14. Rocker Controls Directional controls usually placed at the upper left-hand side of a device. Can be pushed up and down, and most can be clicked in Used for scrolling, selection and action In some rocker controls, the farther in a direction the control is pushed, the faster the scrolling goes.

15. Data Input One of the biggest challenges in UI design for mobile devices is input. Keypad Stylus Input Keyboards

16. Phone Style Keypads Tripple tap and T9 Tripple tap –is the default for all phones when text is required. –No copyright or patent on this method!!! T9 –Predictive text input technology –Uses numeric keypad to enter text, one keypress per character –Many users find it confusing!

17. Phone Style Keypad 1 2 abc 3 def 6 mno 5 jkl 4 ghi 9 wxyz 8 tuv 7 pqrs *0#

18. Example Triple-Tap Key PressedDisplayT9 Key PressedDisplay 6m6o 3md3of 3me3off Pauseme8meet 3med4meeti 3mee6meetin 8meet4meeting 4meetg 4meeth 4meeti 6meetim 6meetin 4meeting

19. PDA Stylus Input Electronic Ink –useful for drawings and text notes Handwriting recognition –Grafiti – Single stroke based Palm –CIC’s Jot – both single and multi-stroke; multiple forms of each character WinCE On-Screen keyboards –Tap each character on keyboard displayed on screen

20. Keyboards: Fastap vs QWERTY Full keyboard on a phone handset! Hills and valley model –Alphabets are hills –Numerals are valleys Press a valley and you end-up pressing four surrounding hills – fat fingers effect –But this is being handled now!

21. Narrow or Wide Fastap

22. Speech Recognition Most natural input for mobile devices No additional space required Most expensive in compute power requirements –Limited vocabulary works for many applications. –Continuous speech recognition is still not a standard part of mobile devices. Most vulnerable in extreme environments “Recognize Speech” vs “Wreak a nice beach”

23. Output: Display A key technology for mobile devices. Most users want high-quality color displays, but –they consume a significant amount of power, and –cost is high.

24. Power Consumption Problem

25. Audio, Communications, etc. Producing sound requires power! 802.11 is power hungry. –There is sleep mode –Bluetooth is better but not ubiquitous Location –GPS is becoming more and more common –Triangulation – but telcos will not share the data with the consumer!

26. How to Program All Those Devices? “Write once, run everywhere” has a lot of appeal! –Write code once –Each device which can run the code has a “Managed Run-Time Environment” to execute the code

27. What is a MRTE? An engine that takes in intermediate language instructions, translates them into machine instructions, and executes them. Two most common MRTEs –JVM – Java Virtual Machine –.NET CLR – Common Language Runtime

28. What Does It Do? MRTEs take machine independent byte code and execute it. –Virtual machine – interpretively executes byte- encoded programs –Garbage collector – automatic management of address space –Just-In-Time (JIT) compiler – translate the byte code into native machine instructions

29. Key Features Dynamically load and execute code Automatic memory management MRTE handles multi-threading

30. Source code compiler Machine + OS object code Source code “compiler” Inter- mediate byte code Machine + OS MRTE

31. Good For Handhelds Given the diversity in Cell Phone / PDA software environments, the ability to generate byte code and have it execute on the device is needed. MRTEs memory management is important so that critical apps will not be affected Memory efficiency is important

32. Java MRTE for Handhelds Sun introduced Java in 1995 Java MRTE is called the JRE (Java runtime environment) and consists of the JVM (Java virtual machine). Sun introduced a small-Java solution and virtual machine, Java 2 Platform, Micro Editition (J2ME), for memory constrained devices in 1999 It has since become popular with wireless handset manufacturers

33. J2ME Inherent protection from memory overruns Memory efficiency of byte code Consortium-based standardization process

34. Java in Wireless Devices Client devices are currently using J2ME released in 2000 –CLDC – Connected Limited Device Configuration Addresses the needs of horizontal market –MIDP – Mobile Information Device Profile Addresses the needs of vertical markets, such as cell phones CLDC, combined with MIDP, is the complete J2ME runtime environment for resource-constrained mobile devices such as phones and entry level PDAs.

35. J2ME Architecture Device Hardware Native System Software / Host OS Native Applications CLDC 1.0 Java Applications MIDP 1.0OEM Classes

36. CLDC 1.0 Provides the platform intended to serve as the lowest common denominator for all resource constrained connected devices –Support for the Java language and virtual machine features –Core libraries (java.io, java.util etc) –Networking –Security Many limitations, e.g., no support for floating point; limited exception handling, no support for user-defined class loaders

37. CLDC Implementations Two virtual machines implement CLDC – KVM and HotSpot K Virtual Machine (KVM) - designed for inexpensive mobile devices - named to reflect that its size is measured in the tens of kilobytes –Suitable for devices with 16/32-bit RISC/CISC microprocessors/controllers, and –With as little as 160 KB of total memory available for the Java technology stack. 128 KB of this is for the storage of the actual virtual machine and libraries, and the remainder is for Java applications.

38. CLDC - Hotspot Targeted at newer generation devices with larger available memory. Suitable for devices with 32-bit RISC/CISC microprocessors/controllers, and with 512KB to 1MB of total memory available for the Java applications.

39. MIDP 1.0 Addresses the needs of a specific vertical market, e.g, mobile phones, PDAs –Application models –User interface support –Persistent storage –Timers

40. CLDC and MIDP Issues Goal of supporting small footprint has been achieved. Problems in application portability and security –Due to lowest common denominator approach, proprietary OEM classes have been developed by vendors, e.g., for audio, additional UI components

41. Status of J2ME Predicted that more than 50% of applications running on wireless client devices will be written in J2ME In 2001, 15 million client devices were Java- enabled In 2007, more than 690 million client devices expected Currently supported by Casio, Fujitsu, Hitachi, Kyocera, LG, Mitsubishi, Motorola, NEC, Nokia, Samsung, Sanyo, Sharp, Sony Ericsson, Toshiba

42. Other MRTE’s Microsoft’s.NET intended to serve the same purpose as Java – but more coherence and less fragmentation across device types for MS-based platforms.NET does better but it only runs on MS OS! Applications are developed using MS Visual Studio tools

43. “Compact Framework”.NET CF.NET is targeted at small foot print devices Released in the 2002 releases of MS Windows CE

44. CF.NET vs J2ME CF.NET supports multiple languages –C++, C#, Visual Basic and Java Script –Programs are compiled into a common intermediate language representation (byte code) that executes in Common Language Runtime Environment (CLR) CF.NET model is more flexible –Avoids the need for proprietary extensions Requires more resources on devices

45. CLR vs JRE Run-Time Services Windows Common Language Runtime (CLR) Code Type Safety Garbage Collector Security Microsoft Intermediate Language (MSIL) J#C++C# VB.NET Run-Time Services Java Java Runtime Environment (JRE) Garbage Collector Security Byte Code MacOS Linux WindowsUnix

46. C Sharp C# is an object-oriented language for building applications for the Microsoft.NET platform, –which provides tools and services for both computing and communications. Includes built-in support to turn any component into an XML Web service that can be invoked over the Internet - from any application running on any platform.

47. The Future of MRTE’s? 1 st generation of wireless data applications (2D games, email, MMS, PIM) are limited. For more data intensive and diverse applications, a consistent software interface layer is needed –Insulate developer from underlying device hardware and software