Scripting Languages for Web - Programming Languages - Lecture Slides, Slides of Programming Languages

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Ada – 1983

History’s largest design effort

• Huge design effort, involving hundreds of people, lots of money and about eight years of designing effort
• Contributions:
  • Packages - support for data abstraction
  • Elaborate exception handling mechanism
  • Facility for generic program units (templates)
  • Facility for concurrency - through the tasking model
• Comments:
  • Competitive design
  • Included all that was known about software engineering and language design at that time
  • First compilers were very difficult;
    • The first usable compiler came nearly five years after the language design was completed

Smalltalk - 1980

• Developed at Xerox PARC, initially by Alan Kay, later by Adele Goldberg
• First full implementation of an object-oriented language - It had data abstraction, inheritance, and dynamic type binding
• Purest object-oriented language yet!
• Pioneered the graphical user interface everyone now uses

C++ - 1985

• Developed at Bell Labs by Stroustrup
• Evolved from C and SIMULA 67
• It has facilities for object-oriented programming, taken partially from SIMULA 67 and were added to C
• Also has exception handling
• Its a large and complex language, in part because it supports both procedural and OO programming
• Rapidly grew in popularity, along with OOP
• ANSI standard approved in November, 1997

Java - 1995

• Developed at Sun in the early 1990s
• Based on C++
• Significantly simplified version of C++
• Supports only OOP
• Eliminated multiple inheritance, pointers, structs, enum types, operator overloading, goto statements
• Includes support for applets and a form of concurrency

C#- 2002

• Part of the .NET framework
• Language for component-based software development
• Based upon C++ and Java
• Took some ideas from Visual Basic
• Intermediate Language (IL)
• Just-in-time compiler
• Brought back pointers, structs, enum types, operator overloading, goto statement
• Has safer enum types, more useful struct types, modified switch statement
• Some other additions

Scripting Languages for Web

• Address the need for computations

associated with HTML documents

• JavaScript is used on the client side and

PHP is used on the server side

• JavaScript – client side

• Primary objective is to create dynamic HTML documents and check validity of input forms
• It is usually embedded in an HTML document
• Its not related to Java

Scripting Languages for Web

• PHP (Personal Home Page) – server side

• Interpreted on the Web Server when the HTML document in which it is embedded is requested by the browser
• Often produces HTML code as an output
• Similar to JavaScript
• Allows simple access to HTML form data – makes form processing easier
• It provides support for many different database management systems and provides web access to databases

Programming Language

Evolution

• 50’s was the time of discovery and

description of programming language

concepts

• We had empirical approach
• Programming languages were regarded solely as tools for facilitating the specification of programs rather than as interesting objects of study in their own right

Discovery and Description

• Development of symbolic assembly language,

macro-assembly, FORTRAN, Algol 60, COBOL and Lisp

• Discovery of many basic implementation

techniques

• Symbol table construction and look-up
• Stack algorithms for evaluating arithmetic expressions
• Activation record stack
• Marking algorithms for garbage collection

Analysis and Elaboration– 60’s

• Analysis for the purpose of constructing models and theories of programming languages
• PL/1, Simula, Algol 68, Snobol
• Elaboration of earlier languages
• An attempt to achieve greater richness by synthesis of existing features and generalization
• Resulted in greater complexity
• Formal languages and automata theory with applications to parsing and compiler theory
• Theory of operational and mathematical semantics were developed
• Language definition techniques were developed
• Basic ideas of program correctness and verification
• Lambda Calculus for abstract structures

Programming Language

Evolution

• Effective software technology – 70’s

• Software Engineering Support – structured design

• 1980’s – Support for SE continued

• 1990’s and 2000’s

• Support for OOP and Internet

• 2010’s – Aspect Oriented Programming?

Software Engineering – 70’s

• From pure research to practical management of the environment
• Decreasing hardware cost and increasing software cost resulted in breaking complexity barrier
• Development of tools and methodologies for controlling the complexities, cost and reliability of large programs
• Structured programming, modular design and verification
• Verifiable languages – Pascal, Modula