This document discusses the evolution of programming languages from machine code to high-level languages and Java. It notes that high-level languages improved readability, maintainability, and reduced the cost of change. It then explains how Java aimed for platform independence through the use of a virtual machine and bytecode rather than native machine code. This allowed Java programs to run on any system that supports the Java virtual machine without being recompiled. The document closes by mentioning some other programming languages that can also run on the Java virtual machine like Groovy, Scala, and JRuby.

1. Java Beyond Java
The world beyond the horizon…
Naresha K.
Software Craftsman

2. What is Java?

3. JAVA BEYOND JAVA
Language ……………….. Platform

4. Language Design Trend
Hardwired
circuits
Machine
Level
Assembly
Level
Compiler/
Interpreter
Intermediate
Language

5. Hardwired Circuits
— Application specific
— Difficult to modify (redesign)
— Cost of change is high

6. Machine Language
— Programmed
— Usually ROMs will store the program
— Somewhat generic
— Cost of change is high
— Difficult to read/ understand

7. Subroutines – Birth of Reuse
— Reusable modules
— No parameter passing

8. Subroutines - example
A
B
S1

9. Assembly Language
— Mnemonics
— Assembler

10. Sub Procedure
— Similar to subroutines
— Parameter passing
— Parameter returning

11. High Level Languages
— Human oriented
— Improved modularity (!!)

12. Language Design Trend - Recall
Hardwired
circuits
Machine
Level
Assembly
Level
Compiler/
Interpreter
Intermediate
Language

13. Why high level languages
— Increased
◦ Readabillity => maintainability
◦ Developer productivity
— Reduced
— Cost of change

14. Moral of the story
— Code (HL) is written for human beings
(developers) not just for machines
— Any dumb can write the code that
machine can understand. Only a good
programmer can write a code that
fellow programmers can understand

15. Compiler Vs Interpreter

16. PLATFORM
DEPENDENCE

17. Dependence on Platform
— Processor Architecture
◦ World length
◦ Big Endian/ Little Endian
◦ RISC Vs CISC

18. Dependence on OS
— Resources managed by OS
— System Calls vary across OS

19. PLATFORM
INDEPENDENCE

20. Goal

21. Platform Independence
Machine Code
Byte Code
Java Source

22. Virtual Machine
— Software implementation of a
computer architecture

23. Virtual Machine
VMWin 32
Win 64
Linux
32
Linux
64
SPARC
Power
PC

24. JAVA PLATFORM

25. RM Strategy
S1 S2
P1 P2 P3
M * N

26. VM Strategy
S1 S2
IL
P1 P2 P3
M + N

27. VM Strategy
Machine Code
Byte Code
Compiler/ Interpreter?
Java Source
Compiler/ Interpreter?

28. VM Strategy
Machine Code
Byte Code
Interpreter
Java Source
Compiler

29. VM Strategy
Machine Code
Byte Code
JIT Compiler
Java Source
Compiler

30. Java Platform
Java
Platform
Java
Language
JVM
JRE
Tools
(Compiler)

32. PROGRAMMING
LANGUAGES OVER JVM

33. JVM Languages
— Groovy
— Scala
— Jython
— JRuby
— Rhino

34. Why not Java
— Expressebility
— Flexibility Vs Performance

35. Why Languages over JVM
— Compiler Need
— Reuse existing libraries
— Use existing tools – profiler, debugger
— Memory management
— Security