Copyright © 2001 Page 122-04-23

Real-Time JavaFact-no-fiction

Java in technical automation

Paul Wijntjes

Consultant

Turnkiek Technical Systems

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Contents

Introduction

Java in embedded

Real Time Java

Demonstrator

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T urnk ie kT e c hnic a l

S y s te m s B V

T urnk ie kB us ine s s

Im pro v e m e nt B V

T urnk ie kIT

S e rv ic e s B V

T urnk ie kP ro c e s s

C o ntro l B V

T urnk ie kH o lding

Im te c h IC T

Offices in:

• Amersfoort

• Delft

• Eindhoven

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Early adopter

Quality solutions

Cost effective and future aimed

In technical industrial & scientific market

Reliable and valued partner

• Give the customer peace of mind• Commitment = commitment• Small things matter• Treat and respect people as people

Mission statement:

Inproduct swV&S systemenProd. Autom.Network Comp

R &DTraffic & TransportProductie Bdr.DefenseAdvanced machinesUtilitiesTelecom

Java

Embedded

Microsoft

Unix /Linux

Platforms Service areas.

Market segments

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Contents

Introduction

Java in embedded

Real Time Java

Demonstrator

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Not only peopleYEAR 2010 Number of subscribers/units (millions)

People

Automobiles

Bicycle

Portable PCs

Motorcycles, Boats, Vending Machines etc

Pets (dogs and cats etc)

Total

120 100

60

50

10

20

360Forecast by DoCoMo based on “Trends in Household Consumption” by Economic Planning Agency,and published materials by Japan Pet Food Manufacturer’s Association etc

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ProFile

ProFile

JavaTM 2 Platform

Hardware / Operating SystemHardware / Operating System

Java Virtual MachineJava Virtual Machine

J2EE APIsJ2EE APIs J2SE APIsJ2SE APIs J2ME APIsJ2ME APIs

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

ProFile

Profiles

Configu-rations

???

Thanks to Chris Laffra, OTI

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Why Java in Embedded ?

More reliable More productive

- Object oriented

- High level

- Component model Inherent networking Less porting effort (if any) Machine code skills deteriorating

Descartes

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Evolution -> Revolution

SEEE ME

-2 y

now

+2 y

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Contents

Introduction

Java in embedded

Real Time Java

Demonstrator

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Yes, but……

What about Real-Time?

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Specification

J-Consortium, RTJWG

- NewMonics, HP, Microsoft, Aonix,...

JCP, JSR-0000001

- Specs

- Reference implementation

- Test suite

- Expected Q4-2001

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Guiding Principles

Applicability to particular Java environments Backward compatibility Write once, run anywhere Current practice versus advanced future features Predictable execution No syntactic extension

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RTSJ: 8 modified areas

1. Thread scheduling and dispatching

2. Memory management

3. Synchronization and resource sharing

4. Physical memory access

5. Asynchronous event handling

6. Asynchronous transfer of control

7. Asynchronous thread termination

8. Exceptions

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1. Thread scheduling and dispatching

Introduction of class RealTimeThread Predictable execution Unanticipated scheduling algorithms can be used Preemptive, Priority-based, FIFO within priority with at

least 28 unique priority levels

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How does it work?

Rt-thread

Time

Priority

Java thread

GC

Rt-thread

Pipe

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2. Memory management

Garbage collection Basic memory areas

- Scoped memory

- Physical memory

- Immortal memory

- Heap memory

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3. Synchronisation and resource sharing

Prevent priority inversion Monitor behavior policy can be set per object. Determinisme

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Priority inheritance

Object

Thread 1

Thread 2

Lock Unlock

Lock

Priority

Time

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4. Physical memory access

Byte-level access to physical memory

Construction of objects in physical memory

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5. Asynchronous event handling

Two classes AsyncEvent

AsynchEventHandler

Implemented scheduler for execution

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AsyncEvent (how it works)

AsyncEvent

bindTo()

abstract class AsyncEventHandler:

run() // final

handleAsyncEvent()

getAndDecrementPendingFireCount()

addHandler()

• Handler implements Schedulable and Runnable interfaces.

Real world event

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6. Asynchronous transfer of control (ATC)

Execution transfer

Time bound

ATC and asynchronous event handling can be combined.

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7. Asynchronous thread termination

Safely transfer of control

New mechanism for stopping threads

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8. Exceptions

New several exceptions

New treatment of exceptions

asynchronous transfer of control

memory allocation

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Implementations

TimeSys, reference implementation JSR-1

OTI/IBM J9

Esmertec, JBed

Insignia Solutions, Jeode

aJile Systems

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Contents

Introduction

Java in embedded

Real Time Java

Demonstrator

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Real time demonstrator

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PC 104 boardPC 104 board

QNX NeutrinoQNX Neutrino

OTI’s J9 + Real-Time ExtensionsOTI’s J9 + Real-Time Extensions

ApplicationApplication

DriversDrivers

motorcontrolersmotorcontrolers

Architecture

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Visual Age Micro Edition

After running 3 threads “simultaneously”

Trace analyzer Memory analyzer

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Lessons learned

Real-Time Java is Really Real-Time

Implementation of specs not complete

OTI’s J9 and VAME work very well

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Summary

Expected exponential growth in J2ME applications

Real-Time Java nearly final

It’s time to make plans to use Real Time Java

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More information

java.sun.com

www.rtj.org

www.drtsj.org

www.embedded.oti.com

www.turnkiek.nl

wijntjes@turnkiek.nl

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Thank you

For your time and attention