Download [] Challenges and Solutions for Embedded Java

Challenges and Solutions for
Embedded Java
Michael Wortley
Computer Integrated Surgery
March 1, 2001
TINI CORBA ORB Project
• Goal: to port Java
based CORBA ORB
to TINI board
• Problem: Converting
from JDK1.3 to
TINI’s embedded
Java
Goals of this Presentation
• Provide background of Java’s benefits
• Show how embedded environment
presents challenges to the Java
platform
• Highlight available solutions
Main Sources
• “Challenges to Embedded Java”
– Charlie McDowell, UC Santa Cruz
– 1998 PowerPoint presentation
• “Technical Overview of Embedded
Java”
– 4/2000, From Sun Website
Other Sources
• “Java Schism?”
– Rick Cook, Java Report 6/99
• “About Java Technology”
– Sun Website
• TINI software information from
www.iButton.com
Goals of this Presentation
• Provide background of Java’s
benefits
• Show how embedded environment presents
challenges to the Java platform
• Highlight available solutions
“Write Once, Run Anywhere.”
Why do Programmers like
Java?
• Compiled and Interpreted
• Easy Upgrades through API
• JVM = Portability
Goals of this Presentation
• Provide background of Java’s benefits
• Show how embedded
environment presents
challenges to the Java platform
• Highlight available solutions
“Challenges to Embedded
Java”
PowerPoint Presentation by
Charlie McDowell, 1998.
Key Points
• Java is superior to C++ in ease of
development, maintenance, and
portability
• Java API and JVM put too much stress
on embedded processors
• Java tends to have slower execution
time
Key Points
• Automatic garbage collection causes
problems
• Java lacks real-time support
Java Memory Requirements
• Storage of Java API
– up to 9 MB for JDK1.1
• JVM
– between 300 and 800 KB
• Garbage Collection Overhead
– copy collectors -> requires 2x max. heap
usage
– conservative collectors -> memory leaks
Java Execution Time
• Interpreted code runs more slowly than
compiled code
• Resolving references prior to execution
reduces run time
• Using final and static methods can
reduce dynamic dispatch of functions
• Garbage Collection eats memory
Garbage Collection
• Part of what makes Java simple
• Problematic for real-time applications
Java and Real-Time
Applications
• Java lacks:
– reliable methods of estimating worst case
– ability to measure CPU time, memory use
– enforcement of time and space budgets
– real-time garbage collection
• IMPROVEMENTS NEEDED!
Suggested Optimizations for
Embedded Java
• Reduce API to free memory
• Use final and static functions to
decrease execution time
• Eliminate automatic garbage collection
• Find ways to improve real-time
performance
Non-Sun Embedded Java
• PERC by NewMonics
– real-time garbage collection
• VxWorks
– only 628 KB
• JN from UCSC
– JIT from Kaffe
– reduced API
Goals of this Presentation
• Provide background of Java’s benefits
• Show how embedded environment presents
challenges to the Java platform
• Highlight available solutions
“Technical Overview of
Embedded Java Technology”
Sun Microsystems
http://java.sun.com/products/embeddedjava/overview.html
Improvements in Sun’s
Embedded Java
• Configurable API
• Configurable JVM
• JavaFilter tool
• JavaCodeCompact
• JavaDataCompact
New Programming Tools
• JavaFilter
– input
• source code
• Java API
– output
• list of necessary API
classes and methods
New Programming Tools
• JavaCodeCompact
– input
• Source Code
• Java API
• list of necessary API
classes and methods
– output
• data structures in C
code
New Programming Tools
• JavaDataCompact
– input
• associated data files
• Java API
– output
• data structures in C
code
How this Relates to TINI
• TINI’s embedded
Java is Sun
compatible.
• Limitted API
• Development Tools
– TINI API
– TINIConvertor
Conclusions about Embedded
Java
• Increasing complexity of embedded
devices will force makers to use high
level language
• Java’s fast development time and
portability are ideal for large
manufacturers
• Competition needed to drive
advancements
So long, and thanks for all the
fish.