TAMZ. Department of Computer Science VŠB-Technical University of Ostrava

Transcription

1 TAMZ 1

2 Contact Information Office: A-1007 Address: Dept. of Computer Science, FEECS 17. listopadu Ostrava-Poruba Phone: Web: 2

3 Course Requirements During the semester: Implementation (10 points) programming of certain assignments in labs, one point for each completed assignment Presentation (5 to 10 points) presentation of pre-selected topic from subject area in labs, minutes. Project (10 to 25 points) implementation of chosen project in JavaME for a mobile device + its defense. Required to complete the course! After the end of the semester: Final exam (20 to 55 points) 3

4 Java Community Process References Java 2 Platform, Micro Edition (JavaME) Sun Developer Network Core J2ME Technology and MIDP J. W. Muchow, 2002, ISBN Developing with J2ME, Second Edition J. Knudsen, 2003, ISBN Wireless J2ME Platform Programming V. Piroumian, 2002, ISBN

5 What is a Mobile Device? A pocket-sized computing device, typically with: a small visual display screen for user output a miniature keyboard or touch screen for user input. Examples: Mobile & cordless phones, pagers PDAs & smartphones Navigation devices (e.g. PNA) Cameras Portable media players Handheld game consoles (e.g. PSP) Tablets, netbooks, UMPCs... 5

6 Limitations of Mobile Devices Small lower-resolution display (sometimes even grayscale/bw) Limited input options (phone/software keyboard) Lower operating memory & internal storage space (the latter partly solved by external memory cards) Limited CPU power + no or limited GPU Limited instruction set (e.g. no floating point arithmetics, no SSE, vector-processing instructions) Network connectivity issues Smaller library of system functions Power considerations... 6

7 Mobile Operating Systems Vendor-specific firmware (generic) EPOC/Symbian OS (Nokia, SonyEricsson,...) Windows-based: Windows Mobile/CE, Windows embedded WP7, Windows RT (8) PalmOS WebOS Linux-based: Android Firefox OS, Maemo, MeeGo, Qt Extended (formerly Qtopia), Openmoko, Tizen, Sailfish OS Debian (ARM), ios Samsung BADA 7

8 Mobile Frameworks JavaME Java 2 Micro Edition Flash Lite commercial HTML5-based frameworks jquery Mobile Sencha Touch PhoneGAP 3 rd party frameworks (of varying quality) for Java-based: Eve (formerly Ewe) J2ME Polish HAXE,... 8

9 Programming languages Java (SE, ME, EE) C/C++ - native libraries, e.g. Android NDK C# - Windows 8, WP7 (Silverlight, XNA) Objective C ios HTML + Javascript + CSS Python Exotic choices: LUA, Lazarus (Pascal), Shell script, PHP, 9

10 Mobile Platforms Comparison.NET CF Java ME Pocket PC 1.0: WM : WM IBM J9,... Windows Mobile Yes Android Monodroid preview-only Java-based, emulators, convertors Symbian OS NO Generic Firmware Yes (problems!) Yes Symbian SDK NO NO PC SDK & emulator Flash Lite (commercial) Windows Mobile 5+ HTC-only? > 03/2006 Flash MX Android SDK NO Yes NO SDK Additional platforms not included in comparison: ios iphone, ipad, ipod - MacOS development only Windows Phone 7 XNA or Silverlight development only Various Vendor-specific frameworks for specific devices 10

11 New platforms changed everything! Device fragmentation Platform fragmetation Vendors try to keep customer by vendor lock-in Applications sold by vendors directly through their AppStore/Marketplace/Market/... 4 dominant platforms in 2012 Android ios Blackberry (US) / Symbian (EU) Windows (Mobile+WP7+Windows RT) Dumb phones still use JavaME (MIDP 3.0 too little too late). 11

12 Why is platform fragmentation bad? Different environment Different APIs Different programming languages (Java, JavaME, Objective C, Silverlight, ) Different SDKs, specific OS needed for SDK and development (Windows, MacOS) The code needs to be written several times We may use Native libraries (usually in C/C++) Android/JavaME basic common parts in Java, GUI/API calls separately HTML 5 for simple applications PhoneGap Platform-independent SDKs 12

13 Best description of current situation Source: 13

14 Java ME 14

15 Why still use JavaME? Basic ideas similar to other platforms, we can demonstrate the basic concepts here before moving to Android Easy-to understand platform with well-defined standards (jcp.org) Still the main choice for dumb phones Basic notions will help when moving to Android Development Per-app revenues still better than Android (150% based on 08/2011 data, but ios has 200%). Source: Mobile Marketing Watch SDK for all 3 major platforms (Windows, MacOS, Linux), Netbeans (or Eclipse) development 15

16 History Java started small, aimed at television set top boxes and other interactive devices. Of course, once it got aimed toward web browsers and applets, the brakes were off. As a result, the platform got all kinds of amazing features like Swing, Java 2D, Java 3D, JDBC, EJB, and so on. With each new API, the size of the platform got bigger and bigger and bigger. So did the runtime footprint. These days, it is not uncommon to see Java virtual machines with a gigabyte or more of heap space. Whether it is called featuritis, bloat, or customer responsiveness, the fact remains that the Java 1 platform was big, and the standard Java 2 platform is huge. 16

17 Java Editions In 1995 the first version of Java, now known as Java Platform Standard Edition (JavaSE), was released. Since that time its landscape has changed significantly. Standard Edition (JavaSE) Designed to run on desktop and workstation computers. Enterprise Edition (JavaEE) This edition is aimed at server-based applications. Contains buit-in support for Servlets, JSP and XML. Micro Edition (JavaME) Designed for devices with limited memory, display and processing power. 17

18 Java Editions Java 2 Enterprise Edition (JavaEE) Java 2 Standard Edition (JavaSE) CDC MIDP CLDC Java Virtual Machine KVM Java 2 Micro Edition (JavaME) 18

19 Generic JavaME Architecture Native Applications Application Profile Application management software (AMS) Configuration Libraries Java Virtual Machine Host Operating System 19

20 Handling Security Any device running a Java application needs protection from malicious code that may access system information or resources. Advanced security model provided by the JavaSE is too memoryconsuming to be included in CLDC devices. The security model, which is provided in the CLDC devices, is the so called sandbox model. In the sandbox model, the applications are run in a closed environment in which the application can only access not secure-sensitive resources. Regardless of the JVM, this type of low-level security is implemented using class file verification. 20

21 Class File Verification Verifying the integrity of class files is not a trivial operation. To spread the work load on a mobile device, verification is done in two steps. 0. Pre-verification A software program is run to insert additional attributes into the class file. This information reduces the amount of time and memory necessary when the JVM carries out step 2 of verification. 1. In-device verification Once a device loads a pre-verified class file, the in-device verifier runs through each instruction. There are several checks done to validate the code. 21

22 Configurations and Profiles Capabilities of devices within the JavaME may vary greatly. A PDA may have a much larger display than a pager. One Java platform will most definitely not fit all. In order to accommodate a broad range of consumer electronics and embedded devices JavaME introduces two new concepts: configurations and profiles. Profile Configuration Libraries Java Virtual Machine 22

23 Configuration A configuration defines a Java platform for a broad range of devices. A configuration is closely tied to a JVM. In fact, a configuration defines the Java language features and the core Java libraries of the JVM for that particular configuration. The dividing line as to what a configuration applies is for the most part based on memory, network connectivity and processing power available on a device. Configuration provides the lowest common denominator for a group of devices. Currently, there are two configurations defined: Connected Limited Device Configuration (CLDC) Connected Device Configuration (CDC) 23

24 CDC versus CLDC CDC is a subset of JavaSE, plus some extra classes. CLDC is a subset of CDC. JavaSE CDC CLCD 24

25 Connected Device Configuration This configuration is designed for devices with more memory, faster processors and greater network bandwidth It is appropriate, at least in the near term, for home automation and automotive navigation, entertainment and telemetry systems. A programming model closer to JavaSE simplifies porting existing desktop clients for enterprise systems to mobile devices that support CDC. CDC is used for example in Multimedia Home Platform (MHP) in DVB set-top boxes 25

26 Connected Limited Device Configuration This configuration is intended for devices with intermittent network connections, small processors and limited memory. Expected targets included two-way pagers, mobile phones and entry-level PDAs. However, in practice, the functionality delivered by CLDC and the associated profiles and optional packages is very close to that of CDC. As a consequence it is used today on most high-end mobile phones, or smartphones, which are replacing PDAs in the marketplace. 26

27 Java Language Differences There are three main areas that distinguish the Java Language for CLDC to those defined in the Java Language Specification. Floating Point Math The CLDC 1.0 implementation of the Java language does not support floats. CLDC 1.1 specifies such support. But MIDP 2.0 only requires CLDC 1.0. Finalization The CLDC does not support the finalize() method because an overhead and processor requirements are too steep. Error Handling The JVM supports a limited set of error handling exceptions due a significant demand on the system's device-dependent. 27

28 JavaME Java Virtual Machines C virtual machine (CVM) classic Java virtual machine used with CDC 32b microprocessor at least 2MB of RAM & 2.5 MB of ROM Kilobyte virtual machine (KVM) used with CLDC 16b/32b (slow) microprocessor limited math, string, and I/O functions lacks some features of classic JVM only a small subset of JavaSE core libraries at least 32kB of RAM & 128kB of ROM 28

29 Java Virtual Machine Differences The Java virtual machine supporting CLDC (KVM) differs from the Java Virtual Machine specification Floating Point Math The implementation of the JVM for CLDC 1.0 lacks support for floating point numbers. Java Native Interface To reduce the potential of corruption to system level information support for invoking native methods was eliminated. Custom Class Loader There are tight controls on a class loader it cannot be replaced, overridden or modified. The loader itself is device-dependent. continued 29

30 Java Virtual Machine Differences continued Reflection Reflection is not available on a JVM supporting the CLDC. Thread Groups The JVM does not support the ThreadGroup class. Finalization The JVM lacks support for finalization. Weak References The JVM does not support weak references to objects. 30

31 Profile A profile supplements a configuration to provide capabilities for a specific family of devices or specific industry segment application need. For example, a configuration provides a generic Java API for battery powered, limited display and processing capability systems, while a profile provides a supplemental Java API specific to cellular telephones, which is a member of this larger group of devices. A profile must supplement a configuration. A profile will not work without the configuration and virtual machine providing the core classes/api and runtime environment. 31

32 Profiles CDC profiles Foundation profile basic CDC profile Game Profile developing game applications Personal Profile complex UI components FP Personal Basis Profile simple UI components (single window) RMI Profile Remote Method Invocation support classes CLDC profiles Mobile Information Device Profile local storage, UI, network PDA Profile better displays, larger memory compared to MIDP KJava Sun-specific API for Palm OS Information Module Profile subset of MIDP

33 Mobile Information Device Profile The Mobile Information Device Profile (MIDP) is a key element of the Java 2 Platform, Micro Edition (JavaME). When combined with the Connected Limited Device Configuration (CLDC), MIDP provides a standard Java runtime environment for today's most popular mobile information devices, such as cell phones and mainstream personal digital assistants. The profile can be characterized by the following features: rich user interface capabilities, extensive connectivity, multimedia and game functionality, over-the-air-provisioning, end-to-end security. 33

34 Information Module Profile The IMP is a strict subset of the MIDP 1.0 specification. The primary difference is that IMP removes MIDP's display and input mechanisms. Instead, IMP devices must provide their own implementation-specific classes to handle any interaction with the user they need. 34

35 How are Configurations and Profiles Defined? Excerpt from JavaME FAQ: Configurations and Profiles are defined by open industry working groups utilizing Sun s Java Community Process Program. In this way industries can decide for themselves what elements are necessary to provide a complete solution targeted at their industry. For more information on the Sun Community Process Program, see: 35

36 MIDP Optional Packages Once again the basic library was insufficient for some applications (remember the JavaSE history), which resulted in the development of several new packages: PDA Optional Package more PDA-specific APIs, e.g. PIM Bluetooth API Bluetooth communication (SDK problem) Wireless Messaging API SMS (MMS) capabilities Location API location tracking SIP API for JavaME VoIP communication,session initiation Presence & IM API JavaME version of JAIN, IM & presence support based on SIP Mobile Media API audio/video controls, streaming media JavaME Web Services API Web Services-related XML classes Security and Trust API Interaction with security smart card Mobile 3D Graphics API 3D graphics, mainly for games... 36