Full HTML for Basic Introduction to Java Tutorial Aimed at Scientific Users

Full HTML for

Basic foilset Introduction to Java Tutorial Aimed at Scientific Users

Given by Geoffrey C. Fox at NAVO Tutorial on Sept 23 1998. Foils prepared Sept 21 1998
Outside Index Summary of Material

Introduction to Applications and Applets

The 3 uses of Java in computing

The 3-tier web-based computing model

History of Java Development

Overall Java Philosophy and Features including security etc.

Java for parallel computing

Performance of Java

Table of Contents for full HTML of Introduction to Java Tutorial Aimed at Scientific Users

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1

Java for Scientific Computing Introduction to Java Tutorial
2

Abstract of Introduction to Java for CSE Tutorial
3

What is Java and What is Good For? for Foil 3

What and Why is Java in a Nutshell?
4

Why is Java worth looking at for Scientific Computing?
5

Why use the Web as basis for HPCC/Scientific Computing Software?
6

The Computing Pyramid
7

Implications of the Computing Pyramid
8

Java Applications and Applets and their use from HTML
9

Architecture of Java Applets
10

Architecture of Java Applications
11

Java Applications in a Nutshell
12

The Simplest Java Application: Hello,World!
13

Java Applets
14

Two ways to run a Java applet
15

The Simplest Java Applet: Hello, World!
16

Displaying your applet from a Web page.
17

More Details on Applet Tags - I
18

More Details on Applet Tags - II
19

<param> Tags and Applets
20

Java vs. JavaScript
21

General Discussion of Role of Java in Scientific and other Computing Applications
22

Computing Services at 3 levels
23

There are (at least) 3 Major Roles for JAVA in Computation -- i.e. it has a role at each layer
24

The 3 Roles of Java
25

Overall Features of Java and Associated Enterprises
26

History of Java Language and Team
27

History of Java Language and Team until Dec. 95
28

More Recent Java History
29

Some Key Java Features and Philosophy
30

Java Features -- It's Simple and Familiar!
31

Java Features -- It's Object-oriented
32

Java Features -- It's Architecture-Neutral
33

Java Features -- It's Portable
34

Java Features -- It's Somewhat Interpreted
35

Java Features -- It's Distributed (and can support parallel computing)
36

Java Features -- It's Robust
37

Java Features -- It's (Hopefully) Secure
38

Java Features -- High Performance
39

Java Features -- It's Multithreaded
40

Java Features -- It's Dynamic
41

Sun's Comparison of Language Features
42

JDK 1.1
43

JDK 1.2
44

Java Web Servers
45

Java Books -- I
46

Java Books -- II
47

Java Beta Books -- III
48

Resources for the Java Programming Language
49

Java Grande Forum Motivation and Activities
50

What is Java Grande?
51

What is Goal of Java Grande Forum?
52

Activities of the Java Grande Forum I
53

Gosling on Operator Overloading
54

Activities of the Java Grande Forum II
55

Java as a Scientific Programming Language Sequential -- Parallel Interpreted -- Compiled
56

Java and Parallelism?
57

"Pure" Java Model For Parallelism
58

Java -- Interpreters and Compilers
59

Hierarchy of Software Levels
60

MPI Java + Message Passing

Outside Index Summary of Material

HTML version of Basic Foils prepared Sept 21 1998

Foil 1 Java for Scientific Computing Introduction to Java Tutorial

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

Geoffrey Fox

Nancy McCracken

Syracuse University

NPAC

111 College Place Syracuse NY 13244 4100

HTML version of Basic Foils prepared Sept 21 1998

Foil 2 Abstract of Introduction to Java for CSE Tutorial

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

Introduction to Applications and Applets

The 3 uses of Java in computing

The 3-tier web-based computing model

History of Java Development

Overall Java Philosophy and Features including security etc.

Java for parallel computing

Performance of Java

HTML version of Basic Foils prepared Sept 21 1998

Foil 3 What and Why is Java in a Nutshell?

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

What is Java?

A simple, object oriented, distributed, interpreted, robust, safe, architecture neutral, portable, high performance, multithreaded, dynamic language.

Java is interesting because

It is both a general purpose object-oriented language along the lines of C++
and it is particularly designed to interface with Web pages and to enable distributed applications over the internet.
It has/will have wonderful tools to support it with best general purpose libraries even seen

Java will dominate as Web will dominate and drive Java as best supported, most widely taught language

Even outside Web, e.g. in scientific computing, Java is as good as and in some (modest) respects better than all other languages

HTML version of Basic Foils prepared Sept 21 1998

Foil 4 Why is Java worth looking at for Scientific Computing?

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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The Java Language has several good design features

secure, safe (wrt bugs), object-oriented, familiar (to C C++ and even Fortran programmers)

Java has a very good set of libraries covering everything from commerce, multimedia, images to math functions (under development at http://math.nist.gov/javanumerics)

Java has best available electronic and paper training and support resources

Java is rapidly getting best integrated program development environments

Java naturally integrated with network and universal machine supports powerful "write once-run anywhere" model

There is a large and growing trained labor force

Can we exploit this in computational science?

HTML version of Basic Foils prepared Sept 21 1998

Foil 5 Why use the Web as basis for HPCC/Scientific Computing Software?

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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HPCC is a small field and Scientific Computing a modest size field with limited resources for very hard problems and must leverage as much software as possible

Web Software provides an excellent pervasive user interface with Java Applets and WebWindows

Web Software provides a potentially excellent high performance object oriented language (Java) for scientific and engineering computation

All(!?) we need to do is to add high performance and special features of scientific computing (math libraries) to the Web!

Technology for generating parallelism (user decomposition, parallelizing compilers) not provided by web and must come from HPCC

HTML version of Basic Foils prepared Sept 21 1998

Foil 6 The Computing Pyramid

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Bottom of Pyramid has 1000 times dollar value and compute power of best supercomputer (tip of pyramid) but supercomputer has high performance network to support close synchronization needed by classic parallel algorithms

HTML version of Basic Foils prepared Sept 21 1998

Foil 7 Implications of the Computing Pyramid

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Web Software MUST be cheaper and better than MPP software as factor of 100 more money invested!

Therefore natural strategy is to get parallel computing environment by adding synchronization of parallel algorithms to loosely coupled Web distributed computing model

HTML version of Basic Foils prepared Sept 21 1998

Foil 8 Java Applications and Applets and their use from HTML

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

HTML version of Basic Foils prepared Sept 21 1998

Foil 9 Architecture of Java Applets

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Browsers (HotJava, Netscape 2.0/3.0/4.0, Microsoft IE ...) supporting Java allow arbitrarily sophisticated dynamic multimedia applications inserts called Applets, written in Java, to be embedded in the regular HTML pages and activated on each exposure of a given page.

web server

Java code

is compiled

to produce

applet codes,

part of web

document

collection

web client, running browser

such as Netscape or IE

executes (restricted)

applet code to display

in browser window

Internet

HTML version of Basic Foils prepared Sept 21 1998

Foil 10 Architecture of Java Applications

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java applications are compiled and run on a machine just like any other general programming language such as C/C++. No web server or network are required although Java applications may also use network connections for distributed computing.

Java code

is compiled

to produce

bytecodes

run by Java

interpreter

to produce

results

Java code

is compiled

to produce

native code

run directly

on machine

for better

performance

HTML version of Basic Foils prepared Sept 21 1998

Foil 11 Java Applications in a Nutshell

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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All Java programs are written into a file with a ".java" extension.

Applications are .java files with a main method which is excuted first.

How to compile and run a Java application (via bytecodes):

Run the compiler on a .java file:
javac MyProgram.java
producing a file "MyProgram.class" of Java bytecodes
Run the interpreter on a .class file:
java MyProgram
which executes the bytecodes

The resources javac and java are part of JDK and are not in Netscape and so are not necessarily available on the same machine as your web server.

HTML version of Basic Foils prepared Sept 21 1998

Foil 12 The Simplest Java Application: Hello,World!

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Since Java is object-oriented, programs are organized into modules called classes, which may have data in variables and subroutines called methods.

class HelloWorld

{ public static void main (String[] args)

{ System.out.println("Hello World!");

}

Each program is enclosed in a class definition.

main() is the first method that is run.

The notation class.method or package.class.method is how to refer to a public method (with some exceptions).

Syntax is similar to C - braces for blocks, semicolon after each statement. One difference: upper and lower case matter!

HTML version of Basic Foils prepared Sept 21 1998

Foil 13 Java Applets

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java applets are classes written in Java which are intended not to run as stand-alone programs (as applications do) but as subprograms of a browser which is already managing a window.

Applets should NOT have main method but rather init, start, paint etc. for displaying on the browser window

The applet should be run through javac compiler getting a .class file as before: javac MyApplet.java

The resulting file MyApplet.class is then stored in the document collection of a web server (hence has a URL location).

Also create an HTML file (say MyApplet.html) with an applet tag to MyApplet.class.

<APPLET codebase="http://myserver.org/mydirectory"
code = "MyApplet.class" width=300 height=100>

HTML version of Basic Foils prepared Sept 21 1998

Foil 14 Two ways to run a Java applet

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Run Netscape 2.0 or later or Internet Explorer essentially anywhere, point the browser at MyApplet.html, and applet is downloaded from the webserver and run by Java interpreter built into the browser. This requires that the .html and .class files are located in the document space of the web server.

Or, primarily for debugging purposes, if you have JDK on your machine, you can run the applet with a program called the appletviewer:

appletviewer MyApplet.html

This way we can compile on places with JDK installed but run almost anywhere!

HTML version of Basic Foils prepared Sept 21 1998

Foil 15 The Simplest Java Applet: Hello, World!

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java applets are part of the class hierarchy that can call methods to display on a screen (within the browser window). One way to draw on the screen is to call the method drawString from the standard method paint.

import java.awt.Graphics;

public class HelloApplet extends java.applet.Applet

{ public void paint (Graphics g)

{ g.drawString("Hello World!", 5, 25);

}

The import statement (similar to an include) allows the use of methods from the Graphics class .

The paint method displays a graphics object on the screen - one of the standard methods that takes the place of main for applets.

Puts this as a subclass of Applet.

HTML version of Basic Foils prepared Sept 21 1998

Foil 16 Displaying your applet from a Web page.

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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You should name the file with your applet name, HelloWorldApplet.java, run the compiler (javac), getting a bytecode file HelloWorldApplet.class, which you put in a web directory.

<html><head>

<title>Simple Hello Page</title>

</head>

<body>

My Java applet says:

<applet code="HelloWorldApplet.class" width=150 height=25>

</applet>

</body></html>

Name of your applet class.

The browser will use a rectangle of width 150 pixels and height 25 pixels to display the applet within the other html.

HTML version of Basic Foils prepared Sept 21 1998

Foil 17 More Details on Applet Tags - I

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Given the following HTML

<APPLET CODE="StockGraph.class"
CODEBASE="http://www.javasoft.com/applets/"
WIDTH=200 HEIGHT=200>
</APPLET>

Runs the "StockGraph.class" executable as an applet.

WIDTH and HEIGHT are attributes that are passed along to the applet.

If the optional CODEBASE attribute is provided, then load the executable image from the directory specified by CODEBASE.

Without the CODEBASE attribute, will look for StockGraph.class in the local server's hierarchy (relative to where the HTML was loaded)
With the CODEBASE attribute will look for StockGraph.class on the given http hierarchy.

Tag and attribute names are case insensitive.

HTML version of Basic Foils prepared Sept 21 1998

Foil 18 More Details on Applet Tags - II

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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<APPLET CODE="StockGraph.class" WIDTH=200 HEIGHT=200

ALT="-- StockGraph Not Supported --"
NAME=SUNW ALIGN=top
VSPACE=5 HSPACE=5>
Put a bunch of text here to be displayed by browsers such as Netscape 2.0 on Windows 3.1 that do not support Java
</APPLET>

ALT specifies text to displayed if the browser understands the applet tag, but if unable to run applets.

NAME specifies the name of this instance of the applet; This will make it possible for applets on the same page to find and communicate with each other.

ALIGN specifies the alignment of the applet. The possible values are the same as those available in the IMG tag (top, middle, bottom, texttop, absmiddle, baseline, absbottom, left, right).

Align=top which aligns top of applet with top of tallest item in the line
Align=texttop which aligns top of applet with top of the tallest text in the line

VSPACE and HSPACE specifies the vertical and horizontal spacing in pixels, around the applet space.

HTML version of Basic Foils prepared Sept 21 1998

Foil 19 <param> Tags and Applets

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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The applet tag can be followed by parameters:

<applet . . . >

<param name=attributename1 value="attributevalue1" >

.......

<param name=attributenameN value="attributevalueN" >

</applet>

The Java program accesses this information by

String attribute;

attribute = getParameter("attributename1");

if( attribute == null )

attribute = yourdefaultvalue;

// null is Java way of saying unset

Typically this processing would be in init() method of Applet

HTML version of Basic Foils prepared Sept 21 1998

Foil 20 Java vs. JavaScript

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Despite the word "java" in the name, JavaScript is a different language than Java, albeit with some similarities.

A JavaScript program is written directly into the HTML page, and is executed by the JavaScript intrepeter, so also executes dynamic web page content in the browser window.

JavaScript is special purpose - it is an object-based language that deals directly with browser entities such as windows, textfields, forms, frames and documents.

JavaScript can respond to browser events (not as many as Java's more complex capabilities with the user interface) such as mouse clicks and user-typed text.

JavaScript is easy and fast to write, but not as powerful as Java.

HTML version of Basic Foils prepared Sept 21 1998

Foil 21 General Discussion of Role of Java in Scientific and other Computing Applications

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

HTML version of Basic Foils prepared Sept 21 1998

Foil 22 Computing Services at 3 levels

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

1:User View: Interoperable Web Interface accessing services through Java Compute Services Framework 2:Network of Java Servers provide distributed services to databases, compute engines, collaboratories, object brokers, instruments

All control at this level
Some coarse grain computing

Back end "Number Crunchers" linked either by communication at level 2 (slowish but easy) or at level 3 (high performance but more work)

Compute processes linked either to servers or together by MPI if parallel

Java Servers

HTML version of Basic Foils prepared Sept 21 1998

Foil 23 There are (at least) 3 Major Roles for JAVA in Computation -- i.e. it has a role at each layer

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java for the Graphical User Interface and client side analysis systems, including visualization: Java has unique advantages over other languages

Java for Coarse Grain Software Integration: as in collaboration and metacomputing

Java has unique advantages over other languages

Java as a high performance scientific language: for "inner" (and outer) loops

Here both parallel and sequential issues are important
Java as good as other languages with higher performance than C++ and advantages of object oriented programming over Fortran and C

HTML version of Basic Foils prepared Sept 21 1998

Foil 24 The 3 Roles of Java

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

HTML version of Basic Foils prepared Sept 21 1998

Foil 25 Overall Features of Java and Associated Enterprises

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

HTML version of Basic Foils prepared Sept 21 1998

Foil 26 History of Java Language and Team

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Starts in 1991 by Project Green --- a group in Sun that detaches from the main campus as a semi-autonomous task force focused on operating software for consumer electronic devices such as smart set-top boxes

Gosling (creator of Sun NeWS which had major conceptual impact both on current Java and Telescript models) realizes that C++ is not adequate and initiates development of a new language Oak, later renamed as Java.

A PDA (Personal Digital Assistant -- codename *7) based on Oak/Java ready in 1993. Green Team incorporates as FirstPerson, Inc.

*7 proposal to Time-Warner rejected in 1993. 3DO deal falls through in 1994. FirstPerson, Inc. dissolves.

Small group (~30 people, now Java Team) continues development and decides to adapt Oak as a Web technology.

HTML version of Basic Foils prepared Sept 21 1998

Foil 27 History of Java Language and Team until Dec. 95

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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An experimental web browser written in Java, called WebRunner and later renamed as HotJava, ready in 1994.

Alpha release of Java and browser HotJava April '95.

Netscape licences Java in May '95 and builds Java into Netscape 2.0 -- This confuses ownership and open-ness of Java

Beta JDK (Java Development Kit) published in summer/fall '95. It is better software but lower functionality than Alpha.

First alpha Java books appear in fall '95 such as a popular overview by SAMS and technical book "Java!" by Tim Ritchey, edited by New Riders.

Dec 4 1995 Business Week cover story on "Software Revolution --- The Web Changes Everything" exposes Java as a breakthrough force in the expanding Web/Internet. Also points out that "Java as a business" is yet to be defined.

In next week, SGI IBM Adobe Macromedia and finally Microsoft adopt/license Java. Java goes into open standards process and is adopted by Web community.

HTML version of Basic Foils prepared Sept 21 1998

Foil 28 More Recent Java History

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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1996 JavaOne Developer's Conference (now held annually in June) focused on applets.

1997 JavaOne focused on JavaBeans and new version of the language JDK1.1, both designed to put Java in line with other developments in component and secure distributed web object computing and use of databases.

1998 JavaOne featured attendance of 14,000+ and focused on Enterprise JavaBeans and other Enterprise classes, developing more on server-side applications.

HTML version of Basic Foils prepared Sept 21 1998

Foil 29 Some Key Java Features and Philosophy

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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First we discuss original Java base language features as discussed in Java: A White Paper by Sun Microsystems -- October 1995 draft by James Gosling and Henry McGilton -- enumerates the original design of Java:

Simple and Familiar
Object-oriented
Architecture-neutral
Portable
Somewhat Interpreted
Distributed
Robust
Secure
High performance
Multi Threaded
Dynamic

Finally we mention additional features added to Java in more recent versions.

HTML version of Basic Foils prepared Sept 21 1998

Foil 30 Java Features -- It's Simple and Familiar!

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java omits several rarely used, poorly understood and confusing features of C++ including operator overloading, multiple inheritance, pointers and automatic type coercions.

It adds automatic garbage collection which makes dynamic programming easier in Java than in C or C++.

No more mallocs!

It also adds 'Interface' construct, similar to Objective C concept, which often compensates for the lack of multiple inheritance by allowing method calling syntax to be "inherited".

The resulting language is familiar as it looks like C++ but is simpler and hence easier to program in.

It also results in a much smaller kernel which is suitable for planned Java ports to consumer electronic devices. Base (alpha) interpreter is ~40Kb, libraries and threads add additional 175Kb.

HTML version of Basic Foils prepared Sept 21 1998

Foil 31 Java Features -- It's Object-oriented

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java model can be viewed as a C++ subset, with some dynamic elements inherited from Objective-C (method overloading, garbage collection).

Structures, Unions and Functions are absorbed into data and methods of Java classes -- Java is Simple!

The strength of Java object-oriented model is not is sophistication but in simplicity and the extensive class library associated with the system (some 250 public classes were released in both alpha and beta).

Java class plays also a role of a communication atom in the Web embedding model. Applet classes identify themselves by names in the HTML applet tag. Applet downloads other classes, present in the applet source. Hence, the Java class names play the role of addressing mode for the distributed Java code database.

HTML version of Basic Foils prepared Sept 21 1998

Foil 32 Java Features -- It's Architecture-Neutral

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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C/C++ programming in a heterogeneous network environment requires use and compatibility across several vendor platforms and the corresponding compilers. This problem is solved in Java by designing platform-independent binary representation called Java bytecode (or opcode).

Java compiler (written in Java and platform-independent) reads Java source and generates Java bytecode. These bytecodes are shipped to client machines upon browser requests.

Each client machine must run Java interpreter which performs runtime execution of Java bytecodes. Java interpreter is written in POSIX compliant ANSI C and needs to be ported to and conventionally compiled (once) on each individual platform.

Once the interpreter is ported, application developers don't need to worry at all about platform specificity and differences between native compilers.

HTML version of Basic Foils prepared Sept 21 1998

Foil 33 Java Features -- It's Portable

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java language offers a uniform abstract (virtual) machine model which is identical for all platforms.

SUN owns the Java Virtual Machine (see online report) -- it is universal while classes can be added by any user

Unlike in C/C++ where various integers match the architecture of a physical machine at hand, Java byte, char short, int and long are always of the same size, equal to 8, 16, 16(unicode), 32 and 64 bits, respectively.

No header files, preprocessors,#define etc.
floating point is always IEEE 754

Differences between vendor specific windowing environments (X Windows, MS Windows, Macintosh) are removed in terms of the Abstract Windowing Toolkit (AWT) metaphor.

AWT is given by ~60 Java classes (alpha) which offer a universal GUI programming model, portable between UNIX, PC and Mac, and translated automatically to native windowing systems on individual platforms by Java interpreters.

HTML version of Basic Foils prepared Sept 21 1998

Foil 34 Java Features -- It's Somewhat Interpreted

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java represents a compromise between fully compiled (like C/C++) and fully interpreted (like Smalltalk or Perl) models.

Java "compiler" produces a binary bytecode output which is portable and much smaller than the real binary for a specific machine (Typical bytecode size is of order of the original source code, within a factor of 2).

Java "interpreter" executes this bytecode and is therefore less dynamic than e.g. Perl interpreter (which performs an equivalent bytecode construction internally and on-the-fly when reading the program source).

In general, the compilation process is: a) time consuming and b) platform specific. Hence, interpreters are built and used to facilitate a) rapid prototyping and/or b) portability. Java model is focused on platform independence but the development throughput is also reasonable since the Java compiler is fast and generates compact bytecode output.

HTML version of Basic Foils prepared Sept 21 1998

Foil 35 Java Features -- It's Distributed (and can support parallel computing)

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Popular TCP/IP based protocols such as FTP or HTTP are supported in terms of network protocol classes.

This implements Java plus message passing and immediately supports various forms of distributed processing.
New protocols, such as PVM and MPI, can be added and dynamically installed.
Parallel computing can be built on top of these base classes.

Distributed computing model of Java is mainly client-server, with Java compiler preparing the opcodes at the server side, and Java interpreter executing it at the client side.

HTML version of Basic Foils prepared Sept 21 1998

Foil 36 Java Features -- It's Robust

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java enforces compiler-time type checking and eliminates this way some error prone constructs of C/C++.

Pointer arithmetic is fully eliminated which allows e.g. for runtime checking of array subscripts and enforces security of the Java model.

Explicit declarations are always required, i.e. C-style implicit declarations are abandoned. This allows the Java complier to perform early error detection.

Rapid prototyping in Java is less natural than in JavaScript,Lisp, Tcl, Smalltalk or Perl, but the software quality assurance of Java is higher than in these more dynamic and 'forgiving' languages.

HTML version of Basic Foils prepared Sept 21 1998

Foil 37 Java Features -- It's (Hopefully) Secure

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java bytecodes are shipped across the network and executed on client machines. Security is therefore a critical issue and strongly enforced in Java.

Java contains its own networking classes which are designed to be secure

Modifications of the C++ model such as eliminating pointer arithmetic and coercion were dictated mainly by the security requirements.

Most viruses are based on acquiring access to private/protected sectors of computer memory which is impossible in Java.

Java opcodes are executed at the client side by Java interpreter which operates exclusively on the virtual memory. Hence, unless there are security bugs in the Java interpreter itself, the model is safe and users cannot create security holes by incorrectly or maliciously written applets.

The bytecodes sent across network are verified at the client which prevents evil/corrupted classes from causing problems

HTML version of Basic Foils prepared Sept 21 1998

Foil 38 Java Features -- High Performance

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java interpreter performs on-the-fly runtime execution of the Java bytecodes which results typically in a satisfactory performance.

NOT true in initial software which is often 100 times slower than C
performance is improved in new "just-in-time" interpreters, which saves code for repeated sections to provide compiled code efficiency after first execution

Support for generating native machine code out of Java bytecodes, viewed as intermediate compiler form, is also provided and useful for performance demanding applications.

The performance of the machine code, generated from Java bytecodes, is comparable to that offered by typical C/C++ compilers on the same platform.

Several of these concepts are in fact similar as in the OSF/ANDF project. Using ANDF terminology, we would call Java compiler a 'producer', and the machine code generator discussed here, an 'installer'. Default Java working mode doesn't use installers but directly interprets the intermediate form (this mode is supported in ANDF by GAI -- Generalized ANDF Interpreter).

Java/HotJava system implements ANDF concepts for the Java language.

HTML version of Basic Foils prepared Sept 21 1998

Foil 39 Java Features -- It's Multithreaded

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java model offers preemptive multithreading, implemented in terms of the Thread class. Thread methods offer a set of synchronization primitives based on monitor and conditional variable paradigm by C.A.R. Hoare. Java threads inherit some features from the pioneering Cedar/Mesa System by Xerox Park that gave birth to Macintosh and object-oriented programming.

A typical use of Java multithreading in applet programming is to have several independent but related simulations (e.g. various sorting algorithms), running concurrently in an applet window. Multithreading is also used internally by the browser to handle multiple document dynamics.

Another interesting application domain are multi-HotJava environments to come such as collaboratory or gaming.

Java threads don't have built-in point-to-point communication primitives. Various thread communication environments can be provided by coupling the thread and network protocol objects.

HTML version of Basic Foils prepared Sept 21 1998

Foil 40 Java Features -- It's Dynamic

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java model is more dynamic than C++ and closer to Smalltalk or Perl.

Subclasses don't need to to be recompiled after superclass implementation is updated.

C++ has "fragile superclass" problem where must recompile children if change anything (method/instance variable) in a superclass or referenced class -- Java resolves references at runtime and avoids this.

Classes have runtime representation (implemented in terms of the Class class) which allows one to look up type of a given object instance at runtime (in C cannot know if pointer is to integer or browser!)

HTML version of Basic Foils prepared Sept 21 1998

Foil 41 Sun's Comparison of Language Features

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

Full HTML Index

Good Fair Poor

Java Smalltalk TCL Perl Shells C C++

Performance

Simple

Object-Oriented

Robust

Secure

Interpreted

Dynamic

Portable

Neutral

Threads

GarbageCollection

Exceptions

HTML version of Basic Foils prepared Sept 21 1998

Foil 42 JDK 1.1

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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A substantial new version of Java released March 97 by JavaSoft.

This release includes many developments both by Sun and by partner companies such as IBM. There are minimal changes to the language - primarily development of new classes to support enterprise computing.

Netscape4.0 and Internet Explorer 4.0 do support JDK 1.1, on some platforms you must explicitly download the "AWT" version to get all of 1.1 support.

Features: better event model in the AWT, Java Database Connectivity (JDBC), Remote Method Interface (RMI), internationalization, security certificates and encryption, and JavaBeans.

http://www.javasoft.com/products/jdk/1.1

HTML version of Basic Foils prepared Sept 21 1998

Foil 43 JDK 1.2

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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This newly released version of Java has additional classes.

It is not currently supported in final release browsers.

It features classes for the "Swing Set", which is many new user interface elements with a more sophisticated look and feel, drag and drop, text editors, printing formatted text, 2D and 3D geometry, image processing and more multimedia classes.

HTML version of Basic Foils prepared Sept 21 1998

Foil 44 Java Web Servers

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Originally, the Java Interpreter was incorporated into browsers such as those from Netscape and Microsoft, but the Web server remained a standard one.

Now Web servers are being developed in Java itself. This leads to more natural integration of the use of Java applets on the Web browsers and Java applications running on the Web server machine.

Java WebServer from Sun - http://jserv.javasoft.com/ - This web server is developed following new Java Server API, which allows for security and encryption servers. WebServer will run Java applications, called servlets, on the server side similarly to CGI scripts.
Jigsaw from the W3 Consortium - http://www.w3.org/pub/WWW/Jigsaw - This web server had the most services but is currently being rewritten so that the model for running Java on the server side will be JavaBeans.

HTML version of Basic Foils prepared Sept 21 1998

Foil 45 Java Books -- I

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java in a Nutshell, by David Flanagan, is the language reference book in the familiar O'Reilly series. The 2nd edition of this book is now out - it omits many examples from the first edition to make room for large section on JDK 1.1 - currently best book reference. Also Java Examples in a Nutshell.

Java, How to Program, by Deitel and Deitel, Prentice-Hall, starts with beginning programming concepts and progresses rapidly through Java language. It has the most programming exercises and also has companion teaching multimedia books.

HTML version of Basic Foils prepared Sept 21 1998

Foil 46 Java Books -- II

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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The Java Programming Language, by Ken Arnold and James Gosling, Addison-Wesley, May 1996, has lots of details on the language basics for intermediate and advanced programmers. It covers threads and i/o packages, but not applets or windowing packages.

All serious computer scientists should read to understand fundamentals

Java Primer Plus, supercharging Web applications with the Java programming language, by Paul M. Tyma, Gabriel Torok, and Troy Downing, Sams.net, concentrates on object-oriented and distributed computing aspects of Java.

HTML version of Basic Foils prepared Sept 21 1998

Foil 47 Java Beta Books -- III

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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There are now many books in the Java Series from SunSoft Press, Prentice-Hall.

core Java, by Gary Cornell and Cay S. Horstmann, offers detailed coverage of the whole language and packages for advanced programmers. Also Volume 2 gives good coverage of advanced topics such as JDBC, RMI, JavaBeans and security.
graphic Java, by Gary McClellan, gives more details on windowing and user interface and includes new classes (not in original Java release) for such things as "rubberbanding".

There are also titles that specifically cover more advanced topics. Here is one:

advanced Java networking, by Prashant Sridharan has chapters on JDBC, RMI, CORBA, JavaBeans and security.

HTML version of Basic Foils prepared Sept 21 1998

Foil 48 Resources for the Java Programming Language

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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The original resource was The Java Language Specification by Sun Microsystems, Inc., March 1995 updated to October 1995 but superceded by Gosling and Arnold Book

http://www.javasoft.com web site has plenty of references including

Tutorial: http://www.javasoft.com/books/Series/Tutorial/index.html
Books:http://www.javasoft.com/java.sun.com/aboutJavaSoft/book-news.html
Collection of Applets: http://www.gamelan.com

Most of the books cited earlier have CDROM's with examples and the JDK.

HTML version of Basic Foils prepared Sept 21 1998

Foil 49 Java Grande Forum Motivation and Activities

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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http://www.javagrande.org

HTML version of Basic Foils prepared Sept 21 1998

Foil 50 What is Java Grande?

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Use of Java for:

High Performance Network Computing

Scientific and Engineering Computation

(Distributed) Modeling and Simulation

Parallel and Distributed Computing

Data Intensive Computing

Communication and Computing Intensive Commercial and Academic Applications

HPCC Computational Grids ........

Very difficult to find a "conventional name" that doesn't get misunderstood by some community!

HTML version of Basic Foils prepared Sept 21 1998

Foil 51 What is Goal of Java Grande Forum?

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java has potential to be a better environment for "Grande application development" than any previous languages such as Fortran and C++

The Forum Goal is to develop community consensus and recommendations for either changes to Java or establishment of standards (frameworks) for "Grande" libraries and services

These Language changes or frameworks are designed to realize "best ever Grande programming environment"

First Meeting Mar 1 Palo Alto at Java 98 -- 200 Attendees set Agenda -- 30 permanent people and further meetings May 9-10, Aug 6-7

Public Discussion SC98 Orlando November 13 (3 hour panel)

http://www.npac.syr.edu/projects/javaforcse

HTML version of Basic Foils prepared Sept 21 1998

Foil 52 Activities of the Java Grande Forum I

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Two major working groups promoting standards and community actions

Numerics: Java as a language for mathematics led by Ron Boisvert and Roldan Pozo from NIST

Changes in Java controversial handling of floating point which currently has goal of reproducible results but this leads to non optimal accuracy
Addition of Complex types or classes
Lightweight classes and Operator overloading -- enables implementation of complex as a class
"Fortran rectangular multidimensional arrays" -- Java naturally has "arrays of arrays"
High quality math libraries with agreed interfaces -- FFT, Matrices, Transcendental functions

HTML version of Basic Foils prepared Sept 21 1998

Foil 53 Gosling on Operator Overloading

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Java Grande 98 Feb 28 98

HTML version of Basic Foils prepared Sept 21 1998

Foil 54 Activities of the Java Grande Forum II

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Distributed and Parallel Computing led by Dennis Gannon and Denis Caromel (INRIA, France)

Performance of RMI (Attractive Java distributed object model - "remote method invocation")
Performance of Java runtime (the virtual machine VM) with lots of threads, I/O, memory use
Parallel Computing interfaces including Java MPI binding
Development of universal (condor, Globus, Legion UNICORE WebSubmit ..) Java interface to computing resources -- enables seamless computing (easier than metacomputing!)

Development of Grande Application benchmarks

http://math.nist.gov/scimark

HTML version of Basic Foils prepared Sept 21 1998

Foil 55 Java as a Scientific Programming Language Sequential -- Parallel Interpreted -- Compiled

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Note Java will have same performance as Fortran

a)when Industry compilers mature b)if Sun accepts Java Grande recommendations

HTML version of Basic Foils prepared Sept 21 1998

Foil 56 Java and Parallelism?

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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The Web integration of Java gives it excellent "network" classes and support for message passing.

Thus "Java plus message passing" form of parallel computing is actually somewhat easier than in Fortran or C.

Coarse grain parallelism very natural in Java

"Data Parallel" languages features are NOT in Java and have to be added (as a translator) of NPAC's HPJava to Java+Messaging just as HPF translates to Fortran plus message passing

Java has built in "threads" and a given Java Program can run multiple threads at a time

In Web use, allows one to process Image in one thread, HTML page in another etc.

Can be used to do more general parallel computing but only on shared memory computers

JavaVM (standard Java Runtime) does not support distributed memory systems

HTML version of Basic Foils prepared Sept 21 1998

Foil 57 "Pure" Java Model For Parallelism

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Combine threads on a shared memory machine with message passing between distinct distributed memories

"Distributed" or "Virtual" Shared memory does support the JavaVM as hardware gives illusion of shared memory to JavaVM

Message Passing

HTML version of Basic Foils prepared Sept 21 1998

Foil 58 Java -- Interpreters and Compilers

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Note Java also integrates compiled and interpreted approaches and so leads to more convenient programming environments

Develop and Test with Interpreters
Production Run with high performance using compilers and optimized libraries

JavaScript is a fully interpreted language but not really Java

Applets are half-way between traditional compiled and interpreted approaches

Web "systems" can behave like Interpreters with interactive commands at client

Web Client

including

Java Applets

Web Server

Java Application Backend

HTML version of Basic Foils prepared Sept 21 1998

Foil 59 Hierarchy of Software Levels

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Numerical Objects in (C++/Fortran/C/Java)

Expose the Coarse Grain Parallelism

Expose All Levels of Memory Hierarchy

a) Pure Script (Interpreted)

c) High Level Language but Optimized Compilation

d) Machine Optimized RunTime

b) Semi- Interpreted

a la Applets

Memory Levels in High

Performance CPU

Nodes of Parallel/ Distributed System

HTML version of Basic Foils prepared Sept 21 1998

Foil 60 MPI Java + Message Passing

From Introduction to Java Tutorial Aimed at Scientific Users NAVO Tutorial -- Sept 23 1998. *

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Naturally one can implement an MPI linkage for Java and this has been implemented by NPAC (mpiJava) Mississippi State and Westminister College (London)

There is no formal definition of Java binding to MPI ad there are some areas of uncertainity

Westminister version automatically links C version of MPI to Java Native Interface (JNI)

NPAC version "optimizes" Java link based on C++ MPI standard noting Java does not support "memory sequence" but with serialization could allow transfer of objects http://www.npac.syr.edu/projects/pcrc/mpiJava

MSU version goes one step further with a version even more tuned to Java

If you have any comments about this server, send e-mail to webmaster@npac.syr.edu.

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