Java%20for%20embedded%20systems

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Java for embedded systems

• Felix G. Hamza-Lup

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Outline

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

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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.

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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
• gt embedded programs are organized as a set of
  individual, but cooperating threads of execution.

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Hardware for embedded applications

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

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Outline

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

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Embedded systems applic. domains

• Machine and process control
• Medical instruments
• Data acquisition
• Network components routers and switches

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Less constraints

• Telephony mobile phones, pagers
• PDAs

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Outline

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

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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)

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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

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Outline

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

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Technical challenges for embedded environment
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Problems with Desktop Java

• Too big JVM JIT (just-in-time)
  compilerlibraries ? 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

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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

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Java embedded alternatives

• Special purpose JVM and core libraries
• JVM with JIT compiler
• Compiled JAVA (instead of interpreted)

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Special purpose JVM and Frameworks

• Suns PersonalJava
• Sun's EmbeddedJava
• JIT compiler
• J2MicroEdition
• JADEs LEAP

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PersonalJava

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

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EmbeddedJava - Goals

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

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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 for linking in auxiliary data
  files such as HTML, image, and sound files.

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Sun's EmbeddedJava Technology
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EmbeddedJava Application Environment
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JIT compiler
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JIT vs. interpreted
Slow
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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

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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

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J2MicroEdition

• A subset of the Java Standard Edition
• Notion of configuration

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J2MicroEdition

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

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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

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JADEs 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

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LEAP Architecture
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LEAP agent communication
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Target devices for LEAP
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Outline

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

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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

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Trends - Real-time threads
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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/

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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/