Electrical Engineer, UFSM, Santa Maria, 1995 Java ... · z simpler programming, when comparingto C/C++or assembly ... Microcontroladores Dedicados. PPGC, UFRGS. z Stepner, D. Nagarajan,

1

DarmstadtUniversity ofTechnology

Java Technology forEmbedded Systems

Eng. Leandro Soares Indrusiak, M. [email protected]

2


n Electrical Engineer, UFSM, Santa Maria, 1995n Master in Computer Science, UFRGS, Porto Alegre, 1998n Assistent Professor, PUCRS, Uruguaiana, since 1998

n PhD. Candidate, UFRGS, Porto Alegrez Advisor : Prof . Dr. Ricardo Reis

n Guest Researcher, TUD, Darmstadtz Advisor : Prof .Dr.Dr.h.c. mult. Manfred Glesner

3


Outline

n Motivationn Embedded Systemsn Java Technology

z languagez application programming interfacez virtual machine

n Java in Embedded Systemsz advantages and disadvantagesz execution possibilitiesz virtual machine options

n Perspectives

4


Motivation

n „By the year of 2002, it is estimated that moreinformation appliances will be sold to consumers thanPCs“ (Business Week)

5


Motivation

n „700 million cell phones to be sold worldwide in 2003,about 80% of them offering connections to the Internet“(Gartner Group)

6


Motivation

n Telecommunicationn Networkingn PDAsn Automotive Electronicsn Aerospace industryn Multimedia (digital cameras, digital

audio players)n Home automation (domotics)n Internet appliancesn Toys and games

7


Embedded Systems

n Embedded systems:z a set of pre-defined, specific functions to be performedz the resources available (e.g., memory, power, processor

speed, computational functionality) are constrained

n Special-purpose computer built into and integral to adevice, used to control, monitor or assist an operation

8


Embedded Systems

n Until recently the vast majority of the embeddedsystems used 8- and 16-bit microprocessors,requiring little in the way of sophisticatedsoftware development tools

n The breaking of the $5 threshold for 32-bitprocessors drove an explosion in high-volumeembedded applications

n A new trend towards integrating a full system-on-a-chip (SOC) promises a further dramaticexpansion for 32-bit embedded applications

9


Java Technology

n Development started in early 90‘s under theGreen Project at Sun Microsystems

n Initial goals included reliable software forconsumer electronics

n With the popularization of Internet, the mainfocus moved to web based programs(Applets and Servlets)

n As the market for embedded systems grows,and as the embedded system designbecomes complex, Java is turning back to itsinitial objective and it is being used to boostthe development of several products

10


Java Technology

n Java Technology may bedivided in four building blocks[VENNERS 98]z Java programming languagez class file formatz Java API (Application

Programming Interface)z Java Virtual Machine (JVM)

Java Source Java API

Compiler

Java class files

Java Virtual Machine

Target Platform

11


Java Language

n Features described in the Java Language Whitepaperreleased in 1995:z simple, familiar - looks like C++, but without its unnecessary

complexities

z object oriented - designed to be OO from ground up,implementing elegantly the OO concepts (inheritance,polymorphism, encapsulation, dynamic linking)

z robust, secure - compile-time and runtime code checking,simple memory management model, exceptions, sandboxsecurity model

12


Java Language

n Features described in the Java Language Whitepaperreleased in 1995:

z high performance -JIT compilers, native code interface, garbagecollectionrunning as backgorund task

z threaded - allows multiple concurrent lightweight processes andprovides synchronization facilities

z dynamic - compiler is strict in its compile-time static checking,but the run-time system is dynamic in ist linking stages

z architecture neutral, portable - intermediate code format(bytecodes) can be executed in several platforms through JVM,data types and arithmetic operations behavior are standardized

13


Java API

n Class libraries covering a wide range of subjects:

z graphic user interfacez 2D and 3D graphicsz threads and syncz i /oz data structuresz networkingz cryptographyz data compressionz multimedia

z e-commercez appletsz servletsz XMLz distributed systemsz telephonyz speech recognitionz database connectionz text processing

and more...

14


Java API

n The first versions of the Java Development Kit had asingle, standard API (JDK 1.0 and JDK 1.1)

n When the Java 2 platform was released (JDK 1.2 andJDK 1.3), different flavors of the API were defined:

J2SETM J2EETM J2METM

15


Java API

n Java 2 Platform, Standard Edition (J2SETM) - tools,runtimes, and APIs for developers writing, deploying,and running applets and applications

n Java 2 Platform, Enterprise Edition (J2EETM) -architecture with an Application Programming Model andCompatibility Test Suite for building enterprise-classserver-side applications

n Java 2 Platform, Micro Edition (J2METM) - highlyoptimized Java runtime environment targeting a widerange of consumer products, including pagers, cellularphones, screenphones, digital set-top boxes and carnavigation systems

16



n The JVM is the key point on Java‘s platformindependency

n It lays between the application and the target system,making it possible to run Java code in mostcombinations of hardware/OS

Java Application

JVM for Unix

UnixWorkstation

Java Application

JVM forWindows

WindowsWorkstation

Java Application

JVM for Palm

Palm Handheld

17



class load subsystem

runtime memory area

methodarea

Javacodestack

heapregs.PCs

nativemethod

stack

executionengine

nativemethodsinterface

nativemethodslibrary

18




runtime memory area

methodarea

Javacodestack

heapregs.PCs

nativemethod

stack

executionengine



•binary code load•security verification•reference resolution

19




runtime memory area

methodarea

Javacodestack

heapregs.PCs

nativemethod

stack

executionengine



• method code storage

20




runtime memory area

methodarea

Javacodestack

heapregs.PCs

nativemethod

stack

executionengine



• frame allocation stackfor each thread

21




runtime memory area

methodarea

Javacodestack

heapregs.PCs

nativemethod

stack

executionengine



• object alocation

22




runtime memory area

methodarea

Javacodestack

heapregs.PCs

nativemethod

stack

executionengine



• program counter

23




runtime memory area

methodarea

Javacodestack

heapregs.PCs

nativemethod

stack

executionengine



• bytecode instructionexecution engineimplemented insoftware, hardware orboth

24



n Java programs comprehend oneor more threads, and each ofthem has its own stack and PC

n The stack is divided in frames,which contain the status of theinvoked methods

n The frame has separate areasfor storing the method localvariables, pointers for theinvoker of the method and theoperand stack

local variables

invoker info

operand stack

local variables

invoker info

operand stack

25


Java Technology Overview

26


Java in Embedded Systems

n Based on its motto for Java - „Write once, runeverywhere“ - Sun Microsystems is pushing Java back tothe embedded software develoment

n One particular API (J2ME) and two specifications(Embedded Java and Personal Java) address the subject

n Another API (JavaCard API) may also be consideredsuitable for embedded systems with limited processingand memory resources - it is designed to run in 100kb

27



n Advantages on using Java as embedded softwarez simpler programming, when comparing to C/C++ or assembly

z OO paradigm behind Java language enforces modularity, dataabstraction and thus design reuse

z rich and useful APIs (one standard and several custom)

z portability

z pointer safe

z array indexing check

z exceptions

z code compactness

28



n Disadvantages on using Java as embedded softwarez resources for runtime environment

z garbage collection

z no direct access to hardware

29



n The execution possibilities of Java code depends onseveral architectural optionsz integration with the rest of the system

y native method call

y separate set of threads

z storage and execution of Java bytecodes

y host machine

y target

z executable code generation

y interpreter

y AOT compiler

y JIT compiler

y bytecode execution

30



n integration with the rest of the system

APIs Java ThreadsC/C++ Tasks

JVM

Native Methods Multitasking OS

Hardware

31



n integration with the rest of the system

Thread 1

Thread 2

Garbage Collector

Virtual Machine

Task A

Task B

Operating System

32



n storage and execution of Javabytecodesz bytecodes stored in target device, but

executed in host (not actually EmbeddedJava, but Embedded Server)

z bytecodes stored in host, but executed intarget device

z bytecodes stored and executed in targetdevice - there might not even be a host

host

target

33



n executable code generation

z interpreter - bytecodes translated at runtime

y slower

y requires memory and processing resources

y keeps with platform independency

z AOT compiler - native code generated at compile time

y faster

y don‘t need runtime environment

y platform dependent

34



n executable code generation

z JIT compiler - bytecodes translated at runtime, but withotimizations

y mid-term solution

y currently being used as default for Sun‘s JDK

z bytecode direct execution - requires hardware-implementedJava Virtual Machine

y faster

y some hardware solutions provide execution of both bytecode and regularinstruction set

35


Perspectives

n picoJava core - licensed under Sun CommunityLicense

n WindRiver RTOS - uses special resources andAOT compilation to allow Java-implemented GUIs

n Esmertec JBed - RTOS + JVM, no additionalsoftware needed

n ARM 9 RISC Core - set of extensions tothe ARM RISC architecture lets an ARM9core directly execute Java bytecodes as ifthey were native instructions

n Kaffe - free and portable software JVM

n GCJ - Gnu AOT compiler for Java

36


Perspectives

n Motorola iDEN series, Nokia 9210and DoCoMo's i503 iMode - first generationof cellular phones supporting J2ME

n Sega develops games for next generationMotorola Phones using J2ME

n JVM for Palm and Symbian OS forhandheld computers

37


Perspectives

n TINI Board, Dallas Semiconductors

38


Acknowledgement

z Ito, S.A. Projeto de Aplicacoes Especificas comMicrocontroladores Dedicados. PPGC, UFRGS.

z Stepner, D. Nagarajan, R., Hui, D. Embedded Application DesignUsing a Real-Time OS. DAC 99.

z Bothner, P. Compiling Java for Embedded Systems.

z www.netrino.comz java.sun.comz www.samsung.comz www.visteon.comz www.teletask.be

z www. motorola.comz www. embeddedjava.netz www.embedded.comz www. sony.comz www. artima.com

Documents

Electrical Engineer, UFSM, Santa Maria, 1995 Java ... · z simpler programming, when comparingto C/C++or assembly ... Microcontroladores Dedicados. PPGC, UFRGS. z Stepner, D. Nagarajan,