Introduction to Network and Web Application

Introduction to Network and Web Application

• Topic: Introduction to Network and Web Application
• Key takeaways: Identify programming languages, explain internet and WWW history, recognize WWW consortium, elaborate on network architecture
• Page 1-2: Shows the title slide for a presentation.
• Page 3: Discusses computer programming languages. Different languages express sets of instructions for digital computers. Instructions can be executed directly as machine language, after substitution from assembly language, or after high-level translation. Few are widely used.
• Page 4: Lists types of programming languages: Machine, Assembly, Algorithmic, Business-oriented, Education-oriented, Object-oriented, Declarative, and Scripting.

Machine Language

• A machine language uses numeric codes for computer operations.
• It consists of binary digits ("bits") which are frequently converted between binary and hexadecimal (base 16).
• Machine language instructions use some bits to represent operations (like addition) and others to denote operands or the next instruction's location.
• Machine language is difficult to read and write compared to human language and varies between computer types.
• Advantages: Fast and efficient computer use, no translator required for execution.
• Disadvantages: Requires memorization of operation codes and memory addresses, makes error correction difficult.

Assembly Language

• Assembly language is one level above machine language. Sometimes called ASM.
• It uses short mnemonic codes for instructions and uses names to reference memory blocks rather than memory addresses.
• Translation to machine language is straightforward.
• Programs are compiled by assemblers (software).
• Each assembler is designed for a specific computer architecture.
• It does not offer sophisticated ways to organize complex information.

Assembly Language (continued)

• Assembly language requires detailed knowledge of internal computer architecture (like input/output devices).
• Example: A program converts data from INPORT to OUTPORT. This program is designed for Z80 microprocessors.

Machine and Assembly Languages (Example)

• Shows an example of machine code and its corresponding assembly code and descriptions.
• Examples of instructions: LOAD, STORE, ADD, HALT.

More...

• Machine language is hardware-dependent, expressed in binary.
• Assembly language is easier to read and write than machine language, but still needs familiarity with the architecture of the specific computer.

Algorithmic Languages

• Designed for expressing mathematical or symbolic computations.
• Used for algebraic operations.
• First high-level languages.
• Examples include FORTRAN, ALGOL, LISP, and C.

FORTRAN

• First important algorithmic language, designed in 1957.
• Used for scientific computations and one- and multi-dimensional arrays.
• Included conditional statements, loops, and a GOTO.
• Allowed for subprograms, which helped reuse common mathematical operations.
• Translated well into machine language.

ALGOL

• Designed by a committee of computer scientists.
• Supported recursive subroutines (to break down complex problems into smaller ones).
• Included block structure, which made larger programs more manageable.

LISP

• Developed in the 1960s for processing lists/data.
• Based on the mathematical theory of recursive functions (dealing with problems by doing repeated smaller versions of the same problem).
• Uses very simple notation for operations.
• Example: (+ a (* b c))
• Often used in artificial intelligence programming.

C

• Developed in 1972 for programming computer operating systems.
• Ability to structure data and programs through smaller units is similar to ALGOL.
• Uses compact notation and allows programmers to operate with data addresses alongside values.
• Uses power of computer internal architecture.
• Widely used to this day.

Business-oriented Languages

• COBOL (Common Business Oriented Language): Primarily used in business since 1959.
• CODASYL (Committee on Data Systems and Languages) developed standards to ensure portability.
• Primarily uses English-like notation for business computations with large amounts of data.

SQL

• Structured Query Language (SQL): Used to organize and query databases (which have collections of records).
• Relational SQL databases let data be queried in a specific relation.
• Commercial database programs often use SQL-like languages.

Education-oriented Languages

• BASIC (Beginner's All-purpose Symbolic Instruction Code): Designed to be user-friendly for novices and many users, well-suited to time-sharing computers.
• PASCAL, designed by Niklaus Wirth: An imperative and procedural programming language. Designed for good programming practices through structured programming. Developed based on ALGOL.

LOGO and HYPERTALK

• Educationally focused languages.

Types of Programming Languages

• High-level languages are often easier to use than assembly language; need compilers/interpreters to translate to machine code.
• Scripting languages were developed to shorten programming processes.

Compiling and Running a Program

• A compiler translates high-level language to Assembly code, then to machine code readable to the computer.
• Different languages, though, have different levels of translation steps.
• An interpreter converts the high-level program directly into machine code during run-time.
• The computer executes machine code directly.

Translator Programs

• Assembler translates assembly language programs to machine language.
• Compiler translates higher-level languages to assembly or machine language.
• Interpreter directly translates and executes code line-by-line.

Properties of Web Languages

• Compiled Languages: Java, C, and C++. Pre-generated machine code to avoid runtime checking.
• Interpreted Languages: JavaScript, JScript, VBscript, Perl, PHP, etc. Data is read, processed usually line-by-line.

Object-Oriented Languages

• Object-oriented programming (OOP) is a paradigm where software is designed around data ("objects").
• Objects are made of data fields (attributes/properties) and behaviour (methods).
• OOP structures programs easily maintained and updated.

OOP (continued)

• Examples of OOP languages include Ruby, Scala, Jade, Emerald, Java, Python, and C++.
• Other languages, like Visual Basic.NET, PHP, JavaScript, work well with OOP structures.

Benefits of OOP

• Modularity/Reusability (reusing code through inheritance techniques)
• Productivity (program quicker with reused libraries)
• Easily upgradable & Scalable (easier to modify existing programs)
• Interface Description (simplified communication between components)
• Security (encapsulation hides complex code)
• Flexibility (methods adapt to different objects/classes)

Criticism of OOP

• Overemphasizes data aspects compared to algorithmic approach.
• Code can be more difficult to write and take longer to compile.

Web Languages Examples

• Client-side Languages: JavaScript, JScript, VBScript, Tcl
• HTML, DHTML, Cascading Style Sheets, AJAX
• Server-Side Languages: ASP, JSP, ColdFusion, IPTSCRAE, Lasso, MIVA Script, PHP, ASP.NET, SMX, XSLT, Ruby, Python, Java, Node.js, PERL

Internet Protocol

• Internet Protocol (IP): Used for data exchange/communication in a packet-switched network. Converts data to messages for transferring between computers.
• IP Addresses: Numeric identifiers used to locate host computers for message delivery. IPv4 has 32-bit addresses and IPv6 uses 128-bit addresses.

Domain Names

• Textual names used by humans to identify computers on the Internet.
• Converted to numerical IP addresses via DNS servers, which make up the system that translates domain names to IP addresses.

World Wide Web

• A system of interconnected documents linked by hypertext, used for data exchange and navigation between computers. This is also often thought of as "the web".
• Created at CERN.
• The web uses HTTP for communication.

Internet vs. Web

• Internet is a foundational network of connected devices.
• The Web is a collection of documents accessible via that network.

Terminologies

• Client: Initiates connection to server,
• Server: Provides the resources or data,
• Web Browser: Used to access and display resources on the web.
• Web Server: Used to store and provide resources.
• URL: Uniform Resource Locator, used to identify resources on a network (usually the web)
• HTTP: Hypertext Transfer Protocol, protocol for communication between web browsers and web servers.

Web Servers

• Software programs that store and deliver webpages to requesting browsers.
• Types of web servers include Apache and IIS, each with their own directory structures and software resources.
• CGI (Common Gateway Interface): An older way to interact between servers and other programs.

URL - Uniform Resource Locators

• Used to identify web documents.
• Format includes scheme (protocol like http), object address (domain name/server), path (specific location on the server).

HTTP (Hypertext Transfer Protocol)

• Protocol used to transfer files/documents, or data across the internet.
• Request-response based format with two parts (Header, Body).

Markup Languages

• HTML, DHTML, XML, XSL, CSS are concerned with web document presentation.

World Wide Web Consortium (W3C)

• An organization for standardizing web technology (like HTML, CSS, etc.).

Explore the fundamentals of network and web application development. This quiz covers important programming languages, the history of the internet and WWW, the role of the WWW consortium, and basic network architecture concepts.