Chapter 2: A Brief History Object-Oriented Programming

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Chapter 2 A Brief History Object-Oriented
Programming

• Presentation slides for
• Object-Oriented Programming
• by
• Yahya Garout
• KFUPM
• Information Computer Science Department

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Outline

• A Brief History Object-Oriented Programming
• The History of Java
• Client-Side Computing
• Bytecode Interpreters and Just-In-Time Compilers
• Security Issues
• Specialization of Interfaces
• The White Paper Description
• Java Is Simple
• Java Is Object-Oriented
• Java Is Network Savvy
• Java Is Interpreted
• Java Is Robust

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Outline

• Java Is Secure
• Java Is Architecture Neutral
• Java Is Portable
• Java Is High-Performance
• Java Is Multithreaded
• Java Is Dynamic

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A Brief History Object-Oriented Programming

• All the major concepts were developed in the
  1960s as part of a language called Simula
• Alan Kay and his group developed a programming
  language named Smalltalk in the 1970s
• Bjarne Stroustrup developed an extension to the C
  language that eventually evolved to the language
  C
• Explosion of the research in object-oriented
  programming techniques began
• In the first major conference on object-oriented
  programming, in 1986, there were dozens of
  languages
• These included Eiffel, Objective-C, Actor, Object
  Pascal, and various Lisp dialects
• Object-oriented programming became mainstream

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The History of Java

• Originally names as Oak and was developed in 1991
  by James Gosling.
• Intended as a language for use in embedded
  customer electronic applications
• This determined the characteristics of the
  language
• Two of the most important features size and
  reliability
• Processors in embedded systems are very small,
  possessing small memory, thus the language must
  be able to translate into very concise encoding
• Embedded systems should almost never fail and
  should respond to exceptional and erroneous
  conditions

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Client-Side Computing

• Internet a classic example of a client/server
  system
• A person working at own computer is a client
• The client application communicates over the
  Internet with another computer, server
• Dynamic behavior by executing programs
• In the past programs executed on the server
• The key idea in client-side is that the server
  transmits the program to the client to execute
  locally

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Bytecode Interpreters and Just-In-Time Compilers

• Client computer must be able to execute the
  program
• Java translates program into bytecode, a machine
  code for a virtual machine
• Bytecode is transmitted to clients
• Client computer must use either interpreter or
  JIT compiler
• Interpreter reads and executes bytecode one by
  one as needed
• Just-In-Time compiler translates bytecode to
  machine code of the client computer

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Security Issues

• Java has a security manager that limits the
  actions performed by the programs from a server
• No file system access
• No transmission of information across internet to
  machines other than client or server

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Specialization of Interfaces

• Programs at the server is structured in terms of
  generic classes, such as window and button
• These classes are the same regardless of the
  system used
• At run-time these components create peer
  components for the client system and is used

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Java Is Simple

• Simpler than C
• Many keywords have been eliminated
• No preprocessor
• Much larger library of high-level development
  tools
• No operator overloading
• No independent functions
• No global variables
• No goto statement
• No structures
• No pointers

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Java Is Object-Oriented

• The only unit of programming is the class
  description
• No functions or variables exist outside of class
  boundaries
• Other languages have object-oriented features on
  top of the non-object-oriented language
• Forces all programs into object-oriented
  structure
• Many benefits of object-oriented design is
  realized

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Java Is Network Savvy

• Designed with Internet in mind
• It is possible to construct programs that do not
  deal with Internet
• Provides a rich set of tools for programming
  across a network
• Classes for describing URLs
• Classes for making connections between client and
  server computers
• Classes for execution in controlled environments
  such as web browsers

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Java Is Interpreted

• Java programs are compiled into byte-code that
  can be stored on any type machine
• Interpreter is used to read byte-code and execute
  it
• Generally slower in execution
• A JIT compiler is used to translate byte-code
  into actual machine code instructions
• This way makes them run as fast as compiled
  programs in the traditional languages

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Java Is Robust

• Extensive use of exception-handling
• Statements generate exceptions not erroneous
  operations
• The semantics insist that you must deal with this
  possibility
• Programmers are forced into thinking about
  potential sources of error
• Automatic memory management, or garbage
  collection
• If programmers forget to release memory resources
  once finished with them, applications will
  eventually fail
• Java run-time system automatically detects and
  recovers memory that is no longer being used by
  the program
• Simplifies the programmers task and is more
  reliable

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Java Is Secure

• Eliminating pointers removed the most common
  source of programming errors
• Array index values are checked for validity
• Java is the first layer in a multilevel security
  system
• Byte-codes are examined before executed for
  errors
• Programs are severely restricted in the type
  operations they can perform
• Computers are safe when running java programs
  brought over the network

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Java Is Architecture Neutral

• Java byte-code does not correspond to an machine
• A java program is the same on all machines
• Although C is a standard language, the
  libraries needed to perform activities differ
  considerably from platform to another
• Java hides application-specific details under a
  layer of abstraction in the standard java library

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Java Is Portable

• Because the library hides architecture-specific
  concepts
• Because byte-codes are the same regardless of the
  machine
• Java programs possess unparalleled degree of
  portability
• The exact program can be compiled on one system,
  then executed on many different types of systems
  

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Java Is High-Performance

• Initially heavy performance penalty
• The technology of java execution has rapidly
  evolved
• JIT compilers allow platform-independent java
  programs to be executed with the nearly same
  run-time performance as conventional compiled
  languages

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Java Is Multithreaded

• One of the first languages designed for the
  possibility of multiple threads of execution
  running in one program
• It is easy to set up multitasking
• The coordination of these parallel processes is
  relatively easy

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Java Is Dynamic

• Moving java programs across the Internet and
  executing them on local computers, permits
  dynamic behavior