Assignment WXGA6101 Individual Project FARAH NAWWAR BIDIN WGA050060 Java

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Assignment WXGA6101 - Individual ProjectFARAH
NAWWAR BIDINWGA050060Java
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PART I INTRODUCTION
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history of language, who designed it and why?

• Bill Joy is widely believed to have been the
  person to conceive of the idea of a programming
  language that later became Java.
• Evolved from a language named Oak. Oak was
  developed in the early nineties at Sun
  Microsystems as a platform-independent language
• Aimed at allowing entertainment appliances such
  as video game consoles and VCRs to communicate.
• Just as the deals with the set-top box
  manufacturers were falling through, the World
  Wide Web was coming to life.
• Their focus shifted to the Internet and
  WebRunner, an Oak-enabled browser, was born.
• Oaks name was changed to Java and WebRunner
  became the HotJava web browser.
• Widely used in mobile application and games
  development.

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• what programming paradigm(s) does it readily
  support?
• Object oriented, multiplatform and generic.
• what application areas is it most suited for?
• World Wide Web Applets
• Cross-Platform Application Development
• Other Network Applications

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• what are features?  
• Platform Independence - Java compilers do not
  produce native object code for a particular
  platform but rather byte code instructions for
  the Java Virtual Machine (JVM). Making Java code
  work on a particular platform is then sim ply a
  matter of writing a byte code interpreter to
  simulate a JVM. What this all means is that the
  same compiled byte code will run unmodified on
  any platform that supports Java.
• Object Orientation - Java is a pure
  object-oriented language. This means that
  everything in a Java program is an object and
  everything is descended from a root object class.

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• Rich Standard Library - One of Javas most
  attractive features is its standard library. The
  Java environment includes hundreds of classes and
  methods in six major functional areas.
• Language Support classes for advanced language
  features such as strings, arrays, threads, and
  exception handling.
• Utility classes like a random number generator,
  date and time functions, and container classes.
• Input/output classes to read and write data of
  many types to and from a variety of sources.
• Networking classes to allow inter-computer
  communications over a local network or the
  Internet.
• Abstract Window Toolkit for creating
  platform-independent GUI applications.
• Applet is a class that lets you create Java
  programs that can be downloaded and run on a
  client browser.

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• Applet Interface - In addition to being able to
  create stand-alone applications, Java developers
  can create programs that can be downloaded from a
  web page and run on a client browser.
• Familiar C-like Syntax - One of the factors
  enabling the rapid adoption of Java is the
  similarity of the Java syntax to that of the
  popular C programming language.
• Garbage Collection - Java does not require
  programmers to explicitly free dynamically
  allocated memory. This makes Java programs easier
  to write and less prone to memory errors.

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what are the claims made of its security,
portability, efficiency, extensibility
/maintainability?

• Security
• The compiler, interpreter, and Java-compatible
  browsers all contain several levels of security
  measures that are designed to reduce the risk of
  security compromise, loss of data and program
  integrity, and damage to system users.
• Considering the enormous security problems
  associated with executing potentially untrusted
  code in a secure manner and across multiple
  execution environments, Java's security measures
  are far ahead of even those developed to secure
  military systems. C and C do not have any
  intrinsic security capabilities.

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• Portability
• One advantage of Java is that its programs can
  run on any platform without having to be
  recompiled. This is one positive aspect of
  portability.
• It goes on even further to ensure that there are
  no platform-specific features on the Java
  language specification.
• For example, in some languages, such as Ada, the
  largest integer varies on different platforms. In
  Java, the size of the integer is the same on
  every platform, as is the behavior of arithmetic.
  Having a fixed size for numbers makes Java
  programs portable.
• The Java environment itself is portable to new
  hardware and operating systems, and in fact, the
  Java compiler itself is written in Java.

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• Efficiency
• Java is less efficient than Fortran, C, C and
  probably half-a-dozen other languages.
• When interpreted, Standard Java is about 30-60
  times slower than C.
• When Java is compiled by a just-in-time compiler
  (jit), it seems to be about 3-6 times slower than
  C. Java compiler technology is improving rapidly,
  but how efficient it can get relative to other
  languages is unclear.
• .
• Java's just-in-time performance acceptable for
  prototyping small- to medium-sized problems.
• However, for large field data examples, we may
  have to re-implement our application in a better
  performing language, after we developed it in
  Java.

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• Extensibility/maintainability

• Java is also an excellent language for
  manipulating XML data.
• The Java 2 platform provides an
  architecture-neutral means to write
  object-oriented applications that scale well over
  time, have a shorter development cycle and have
  improved maintainability.
• Java comes with a rich, standard library of
  APIs. This allows developers to leverage a large
  body of pre-existing code modules for effective
  programming.
• Programs in Java which use standard library
  classes are easier to understand and extend than
  those which rely on complicated, homegrown
  classes.

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describe the compilation/interpretation/execution
model it uses.

• Java programs normally go through 5 phases to be
  executed ( edit, compile, load, verify and
  execute).

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• Interpreter
• An interpreter is needed in order to run Java
  programs. The programs are compiled into Java
  Virtual Machine code called bytecode.
• The bytecode is machine independent and is able
  to run on any machine that has a Java
  interpreter. Normally, a compiler will translate
  a high-level language program to machine code and
  the code is able to only run on the native
  machine. If the program is run on other machines,
  the program has to be recompiled on the native
  machine.

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• JVM
• This VM sits between the Java program and the
  machine it is running on, offering the program an
  "abstract computer" that executes the Java code
  and guarantees certain behaviors regardless of
  the underlying hardware or software platform.
• Java compilers turn Java programs not into
  assembly language for a particular machine but
  into a platform-neutral "byte code" that the
  machine-specific VM interprets on the fly.

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PART II

• DESCRIPTION OF THE LANGUAGE
• USING COMPARISON OF VARIOUS LANGUAGES

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Scalar data objects
Single-valued data types, that can be used for
individual variables, constants, etc
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Composite objects
Composite objects are several objects and scripts
bundled together exposed to the application as a
single object.
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Structured objects
A structured data object is a user-defined data
type with elements that are not atomic rather,
they are divisible and can be used either
separately or as a single unit
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Abstract data types
Abstract data type (ADT) is a specification of a
set of data and the set of operations that can be
performed on the data. Such a data type is
abstract in the sense that it is independent of
various concrete implementations.
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Active Objects
An active object is an instance of a class with
encapsulated behavior, running one or more
separate threads. (tasks, processes)
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Below is the comparison of C, C and Java
languages
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PART III -

• FINAL EVALUATION

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• 1. Do you have any basis to agree or disagree
  with any claims made of its security,
  portability, efficiency, extensibility/maintainabi
  lity?
• Yes I agree with all the claims made against its
  security, portability, efficiency,
  extensibility/maintainability.
• Security Java perform a number of run-time
  checks to detect errors early.
• Portability Can be run on almost all types of
  OS and machines.
• Efficiency Less efficient than most languages
  as the compilation process takes time but other
  features (such as suitable and easy to use for
  networking programs RMI socket programming and
  multithreading) seems to attract programmer to
  use Java even it is slow in execution.
• Extensibility/maintainability Java utilizes
  standard library classes which are easier to
  understand and extend than those which rely
  homegrown classes
• 2. What aspect of this language did you find most
  difficult to learn/understand?
• - JDBC(TM) Database Access.
• - Concurrent programming with threads.
• - Handling exceptions.
• - Socket Programming and multithreading

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• 3. How would you rate the programming
  environment? compiler/interpreter messages?
• - Slow but still acceptable and actually it is
  rapidly improving.
• 4. Would you use this language again and if so
  what for? if not, what would you choose to use
  instead and why?
• - Yes. In socket programming. One of the
  reasons why I use Java because it is opensource
  and its development tools can be downloaded for
  free from Sun Microsystems website.
• 5. Design mistakes (in your opinion or the
  opinion of others)? Have they been corrected in
  other languages that were a follow-on. What if
  anything is missing in your opinion?
• - The slow execution time. I think it cannot be
  called as design mistakes but it is unavoidable
  things as its program purposely designed to be
  compiled into Java Virtual Machine bytecode first
  so that it will enhance the mobility part.
  There is no perfect language to suit the entire
  applications and programmers requirements. It
  depends on the programmers to master the
  language, minimize the defects, optimize its
  advantages and exploit its features in order to
  write efficient, easy-to-maintained, secured and
  portable programs to satisfy all the requirements.

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References

• Schiffman, H., 1997, Thoughts on Java
  http//reality.sgi.com/shiffman/Java-QA.html.
• http//www-128.ibm.com/developerworks/db2/library/
  techarticle/dm-0506melnyk/
• http//ei.cs.vt.edu/book/chap1/java_hist.html
• http//www.engin.umd.umich.edu/CIS/course.des/cis4
  00/java/java.html
• http//sepwww.stanford.edu/oldsep/matt/join/java/F
  ig/paper_html/node8.html
• http//www.adahome.com
• http // en.wikipedia.org
• Harold, Elliotte R. "comp.lang.java FAQ."
  
• Harvey M. Deitel and Paul J. Deitel, Java How to
  Program, 6th Edition, DeitelDeitel, Prentice
  Hall
• Terrence W. Pratt and Marvin V. Zelkowitz,
  Programming Languages Design and Implementation,
  Fourth Edition, Prentice Hall, 2001

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I only developed a simple chat application which
is 110 lines of codes. This program basically can
support multiple clients from different machines
but clients must change the servers IP address
according to IP address of the machine that
launches the server file. Once the server file is
executed, it will start listening for clients
connection on port 8000. This program deploys the
concept of Transmission Control Protocol (TCP).
Actually I have already enhanced this program for
other subjects (WRGA6318 and WRGA6315) projects
purpose. Unfortunately, even it is more
efficient, portable and user-friendly the
enhanced version is more than 400 lines of codes
which is not match with the requirement. (Only
simple program with 100-200 LOC)
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TCPChatServer.java

• import java.net.
• import java.io.
• import java.awt.
• import java.awt.event.
• import javax.swing.
• import java.util.
• public class TCPchatServer extends JFrame
  implements ActionListener
• private JTextField jtf new JTextField()
• private JTextArea jta new JTextArea()
• private ServerSocket serversocket
• private Socket socket
• private DataInputStream in
• private DataOutputStream out
• public static void main(String args)
• new TCPchatServer()
• public TCPchatServer()
• JPanel p new JPanel()
• p.setLayout(new BorderLayout())
• p.add(new JLabel("Message"),
  BorderLayout.WEST)

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• try
• jta.append("Server started at "new
  Date()"\n")
• serversocketnew ServerSocket(8000)
• jta.append("Waiting for connection""\n")
• socketserversocket.accept()
• jta.append("Connection successfull""\n")
• while(true)
• innew DataInputStream(socket.getInputStream())
  
• outnew DataOutputStream(socket.getOutputStream
  ())
• String messagein.readUTF()
• jta.append("\nClient "message)
• catch(IOException e)
• jta.append("")
• System.err.println(e)
• public void actionPerformed(ActionEvent
  e)
• if(e.getSource()jtf)
• try
• String messagee.getActionCommand()
• jta.append("\nServer "message)

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TCPChatClient.java

• import java.net.
• import java.io.
• import java.awt.
• import java.awt.event.
• import javax.swing.
• import java.util.
• public class TCPchatClient extends JFrame
  implements ActionListener
• private JTextField jtf new JTextField()
• private JTextArea jta new JTextArea()
• private Socket socket
• private DataInputStream input
• private DataOutputStream output
• public static void main(String args)
• new TCPchatClient()
• public TCPchatClient()
• JPanel p new JPanel()
• p.setLayout(new BorderLayout())
• p.add(new JLabel("Message"),
  BorderLayout.WEST)
• p.add(jtf, BorderLayout.CENTER)

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• setTitle("Client")
• setVisible(true)
• setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
• try
• jta.append("Client started at "new
  Date()"\n")
• socketnew Socket("localhost",8000)
• while(true)
• inputnew DataInputStream(socket.getInputStream(
  ))
• outputnew DataOutputStream(socket.getOutputStre
  am())
• String messageinput.readUTF()
• jta.append("\nServer "message)
• catch(IOException e)
• jta.append("")
• System.err.println(e)
• public void actionPerformed(ActionEvent e)
• if(e.getSource()jtf)
• try
• String messagee.getActionCommand()
• jta.append("\nClient "message)