challenges and solutions for embedded java michael wortley computer integrated surgery march 1, 2001
TRANSCRIPT
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.