JVM Machine Architecture

Java Implementation :

• Compiler and Virtual Machine
• Compiler produces bytecode
• Virtual machine loads classes on demand, verifies bytecode properties, interprets bytecode
• Why this design?  Bytecode interpreter/compilers used before Pascal “pcode”; Smalltalk compilers use bytecode Minimize machine-dependent part of implementation Do optimization on bytecode when possible Keep bytecode interpreter simple For Java, this gives portability Transmit bytecode across network.