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Java for embedded systems

Java for embedded systems. Felix G. Hamza-Lup. Outline. Embedded systems characteristics Application domains Java characteristics Java in embedded systems Future trends References. Embedded systems. Real-Time systems

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Java for embedded systems

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  1. Java for embedded systems Felix G. Hamza-Lup

  2. Outline • Embedded systems characteristics • Application domains • Java characteristics • Java in embedded systems • Future trends • References

  3. Embedded systems • Real-Time systems • Timing constrains play a critical role in their design and implementation. • Have dedicated functionality i.e. designed strictly for a specific set of tasks • Incorporate relatively low-speed microprocessors and may have a limited amount of memory.

  4. Embedded systems - Inputs • Random • Short-lived external signals • Processor must interrupt whatever else it is doing to capture the data, or it will be lost => embedded programs are organized as a set of individual, but cooperating threads of execution.

  5. Hardware for embedded applications • Most embedded systems are housed within a highly-constrained box. • lack of space • excessive vibration => embedded applications will be structured as a small section of initialization code that starts the programs from a ROM disk

  6. Outline • Embedded systems characteristics • Application domains • Java characteristics • Java in embedded systems • Future trends • References

  7. Embedded systems – applic. domains • Machine and process control • Medical instruments • Data acquisition • Network components: routers and switches

  8. Less constraints • Telephony: mobile phones, pagers • PDAs

  9. Outline • Embedded systems characteristics • Application domains • Java characteristics • Java in embedded systems • Future trends • References

  10. Characteristics • Portability – platform independence • Software reuse – OO • Simplicity – easy to learn • Safety and security • JavaTM Authentication and Authorization Service (JAAS) • JavaTM Cryptography Extension (JCE) • Secure Socket Extension (JSSE)

  11. Some key characteristics • The key characteristics of Java that make it attractive as a specification language for embedded systems are: • Built in multithreading and synchronization • Lack of pointer arithmetic • Automatic memory management

  12. Outline • Embedded systems characteristics • Application domains • Java characteristics • Java in embedded systems • Future trends • References

  13. Technical challenges for embedded environment

  14. Problems with “Desktop” Java • Too big: JVM + JIT (just-in-time) compiler+libraries  16 MB • Too slow: 5 x slower than C code • No notion of address: most often hardware is accessed referring to a specific address • Security, portability, dynamic behavior – not needed in embedded systems

  15. Problems with “Desktop” Java • Java Garbage Collector- collect unused memory • JCG – dangerous in embedded systems “stop-the-world effect” • Memory allocation is not fast enough and not predictable

  16. Java embedded: alternatives … • Special purpose JVM and core libraries • JVM with JIT compiler • Compiled JAVA (instead of interpreted)

  17. Special purpose JVM and Frameworks • Sun’s PersonalJava • Sun's EmbeddedJava • JIT – compiler • J2MicroEdition • JADE’s LEAP

  18. PersonalJava • Re-implements the full set of Java APIs defined by the Java application environment • Fits into smaller devices with more limited memory configurations

  19. EmbeddedJava - Goals • Standardize software development for embedded devices • Integrate a compact EmbeddedJava application environment directly into new devices • Small adjustable memory footprint <= Configurable APIs based on application.

  20. EmbeddedJava - Sun's advanced tools streamline • JavaFilter - builds a list of the specific fields and methods used by the Java platform to run the Java application • JavaCodeCompact - optimizes the code by removing unused parts of the platform. • JavaDataCompact– forlinking in auxiliary data files such as HTML, image, and sound files.

  21. Sun's EmbeddedJava Technology

  22. EmbeddedJava Application Environment

  23. JIT compiler

  24. JIT vs. interpreted Slow

  25. JVM/JIT compiler & Products • Dynamic compilation technique using a JIT compiler but tradeoff between: • performance • memory consumption • startup time • KAFFE JIT- one order of magnitude better execution time than Sun's JDK VM • SuperCede VM - performs 58% and 91% faster then JDK • Guava by Softway -better than Sun's JDK 1.0.2 VM • Microsoft's JVM/JIT- in Internet Explorer ; PC Magazine, “is the fastest JVM/JIT for the PC market.” • KVM – Kilo Virtual Machine – small code size kernel

  26. Compiled JAVA • Java  native machine language • Seems to be the current trend • “Bye, bye” • portability • load new classes on-the-fly • Best real-time behavior

  27. J2MicroEdition • A subset of the Java Standard Edition • Notion of configuration

  28. J2MicroEdition • CDLC config. • 160-512 kB of memory • 16-32 bit processor • network connectivity • J2ME Wireless Toolkit • debugging capabilities • emulators

  29. JADE • Java Agent DEvelopment Framework • Software framework fully implemented in Java language • A middle-ware that simplifies the implementation of multi-agent systems • Complies with the FIPA specifications

  30. JADE’s LEAP on embedded systems • Lightweight Extensible Agent Platform • LEAP is an extension of JADE to enable it to run on wireless devices and PDA's such as cell phones and Palms • 02/05/02 - LEAP 2.1 has been released

  31. LEAP Architecture

  32. LEAP agent communication

  33. Target devices for LEAP

  34. Outline • Embedded systems characteristics • Application domains • Java characteristics • Java in embedded systems • Future trends • References

  35. Trends • Some constraints are relaxed: more memory, cheaper CPUs … • Real-time functionality - delivered by OS not by JVM • Tendency to link Java code with OS proprietary code • Real-time threads parallel to JAVA threads • New distributed services

  36. Trends - Real-time threads

  37. References (1) • http://java.sun.com/products/embeddedjava • “What are the advantages of Java in embedded systems?” F.Mueller, ECE 2002 • “Using Java in Embedded Systems” V.Ivanovic, M. Mahar, Circuit Cellar, 1999. • “Java on embedded systems” M.Gafen, NSI.com. • “Personal Java – Application Environment Specification v.1.1.2” 1999. • Embedded systems conferences: http://www.esconline.com/

  38. References (2) • “LEAP: a FIPA platform for mobile and handheld devices” Frederico B., Agostino P. • “Introduction to Java 2 Micro Edition”, Jeff Brown, OCI (Object Computing Inc) • JADE: http://sharon.cselt.it/projects/jade/ • LEAP: http://leap.crm-paris.com/ • FIPA: http://www.fipa.org/

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