Java Architecture Perspective.pdf

1MASSACHVSETTS INSTITVTE OF TECHNOLOGYDepartment of Electrical Engineering and Computer Science6.001|Structure and Interpretation of Computer ProgramsFall Semester, 1998Lecture Notes, December 3 { JavaJava: From a Marketing PerspectiveJava is a \fundamentally new way of computing. \It works everywhere.Java: From a Legal PerspectiveFrom court order in preliminary injunction, Sun v. Microsoft, Nov. 18, 1999:\Suns Java Technology is a collection of programming components that create a standard, platform-independent programming and runtime environment. Suns Java Technology has two basic ele-ments: the Java programming environment and the Java runtime environment.\The Java programming environment allows software developers to create a single version of pro-gram code that is capable of running on any platform which possesses a compatible implementationof the Java runtime environment. The Java programming environment comprises (1) Suns speci-cation for the Java language, (2) Suns specication for the Java class libraries and (3) the Javacompiler.\The Java runtime environment comprises the Java class libraries and the Java runtime interpreter.A system platform or browser program that implements the Java runtime environment can executeapplication programs developed using the Java programming environment. Java: Architecture Perspective 6.001, Fall Semester, 1998|Lecture Notes, December 3 { Java 2Jave code:void spin() {int i;for (i = 0; i 100; i++) {; // Loop body is empty}}Java VM instructions:Method void spin()0 iconst_0 //Push int constant 01 istore_1 //Store into local 1 (i=0)2 goto 8 //First time dont increment5 iinc 1 1 //Increment local 1 by 1 (i++)8 iload_1 //Push local 1 (i)9 bipush 100 //Push int constant (100)11 if_icmplt 5 //Compare, loop if (i100)14 return //Return void when doneJava Bytecodes:3 60 167 0 8 132 1 1 27 16 100 161 0 5 177Java: From a Language Design PerspectiveJava design goals, as summarized in The Java Language: A White Paper, Sun Microsystems:1