Computer Science Lecture 4 Part 2: World Wide Web and Networks

The World Wide Web (WWW)

  • Definition: The World Wide Web, commonly referred to as the Web, is a massive collection of websites or web pages stored in specialized computers known as web servers and connected to local computers globally through the internet.

  • Content Types: Websites on the Web contain a variety of digital media, including:

    • Text pages.

    • Digital images.

    • Audios.

    • Videos.

  • Global Access: Users possess the ability to access the content hosted on these sites from any location in the world over the internet using their personal devices.

  • Foundational Building Blocks: The primary components of the Web are web pages.

    • Formatting: Web pages are formatted using Hypertext Markup Language (HTML).

    • Connectivity: Pages are interconnected by links known as "hypertext" or hyperlinks.

    • Access Protocol: Pages and links are accessed via the Hypertext Transfer Protocol (HTTP).

Uniform Resource Locator (URL)

  • Identification: The URL serves as the dedicated address for a specific web page.

  • Website Definition: A website is defined as a particular collection of web pages that are systematically organized under a specific URL.

  • Examples of URLs:

    • www.facebook.com

    • www.google.com

  • Storage and Server Distribution:

    • Small Websites: Typically store all of their web pages on a single web server.

    • Large Websites and Organizations: Big websites or international organizations distribute their web pages across different servers located in various countries.

    • Performance Optimization: This distributed server strategy ensures that when users in a specific country search a site, they receive information quickly from the nearest physical server, reducing latency.

Differences Between the World Wide Web and the Internet

  • The Internet:

    • It is a worldwide network of hardware devices, including computers, laptops, and tablets.

    • It serves as the underlying infrastructure that enables users to perform actions such as sending emails to other users or engaging in online chats.

    • Example: When sending an email or chatting online, you are utilizing the internet infrastructure.

  • The World Wide Web (WWW):

    • It represents a specific method of requesting info; it is a web page request initiated from a user's computer using a browser.

    • The web server then sends that specific page back to the user's browser.

Operational Mechanics of the World Wide Web

  • Architectural Format: The Web operates based on the internet's fundamental client-server model.

  • Role of Web Servers: Servers are responsible for storing and transferring web pages or specialized information to user computers on the network whenever users request them.

  • Web Server Software: A web server is a software program designed to serve the specific web pages requested by web users via a browser interface.

  • The Client: The computer belonging to a user who requests documents from a server is officially known as the client.

  • The Browser: This is the software installed on the user's computer that allows them to view and interact with the documents retrieved from the server.

  • Data Flow Diagram Principles:

    • Client Devices: Desktop, PC, or Laptop.

    • Request Cycle: The client sends an HTTP request.

    • Transport: The request travels through the Internet.

    • Processing: The Web Server receives the request and interacts with a Database if necessary.

    • Response Cycle: The server returns an HTML response back to the client.

Core Technologies for Transferring Web Pages

  • Triggers: The World Wide Web starts working the moment a user opens a browser and types a URL into the address bar or performs a search on a search engine like Google.

  • The Three Main Technologies:

    1. Hypertext Markup Language (HTML): The language of the content.

    2. Hypertext Transfer Protocol (HTTP): The communication protocol.

    3. Web Browsers: The viewing and interaction software.

Hypertext Markup Language (HTML)

  • Purpose: HTML is the standard markup language used exclusively for the creation of web pages.

  • Organizational Function: The language is used to organize distinct pieces of content within a document.

  • Supported Content Elements:

    • Headings.

    • Paragraphs.

    • Tables.

    • Images.

  • Display Role: HTML is essential for displaying text, images, and various other digital resources through a web browser.

Hypertext Transfer Protocol (HTTP)

  • Function: HTTP is the protocol that enables the World Wide Web to function smoothly and efficiently.

  • Operating Model: It is based strictly on the client-server model.

  • Execution Flow: When a user enters a URL into a browser, an HTTP command is dispatched to the relevant web server, which subsequently transmits the requested web page back to the user.

Internet, Intranet, and Extranet Overview

  • The Internet:

    • A global network comprised of billions of computers and electronic devices.

    • Used for accessing nearly any information, communicating with anyone globally, and various other digital tasks.

  • The Intranet:

    • A private network contained within a specific enterprise.

    • Used to securely share company information and computing resources among employees only.

    • Intranet Advantages:

      • Ease of access for employees to important information, links, applications, forms, and databases of company records.

      • Security Management: Often utilizes a database including all employee usernames with specific access rights to maintain network security.

      • Secure document storage.

      • Facilitation of knowledge sharing.

      • Increases internal communication.

      • Connects employees across the organization.

      • Automation: Streamlines daily activities by automating repeatable tasks, thereby increasing employee productivity.

      • Integrates seamlessly with third-party tools.

  • The Extranet:

    • A private network that enterprises utilize to provide access to trusted third parties.

    • Target Users: Customers, partners, vendors, and suppliers.

    • Access Control: Allows external businesses to gain specific information without being granted access to the organization's entire internal network.

    • Authentication: Users are selected and validated through user IDs, passwords, and other authentication mechanisms on a login page.

    • Extranet Advantages:

      • Ability to exchange large volumes of data using Electronic Data Interchange (EDI).

      • Facilitates sharing of product data or catalogs with business partners.

      • Enables sharing of services, such as online banking applications.

Comparative Analysis of Network Types

  • Point of Difference: Accessibility of Network

    • Internet: Public.

    • Intranet: Private.

    • Extranet: Private.

  • Point of Difference: Availability

    • Internet: All over the world.

    • Intranet: Specific to an organization.

    • Extranet: Restricted area up to an organization and some of its stakeholders or related entities.

  • Point of Difference: Coverage

    • Internet: Global system.

    • Intranet: Specific to an organization.

    • Extranet: Accessible only to members of the organization and external members with specific logins.

  • Point of Difference: Accessibility of Content

    • Internet: Accessible to everyone who is connected.

    • Intranet: Accessible only to the members of the organization.

    • Extranet: Finalized for members of the organization and external members with authorized logins.

  • Point of Difference: Number of Computers Connected

    • Internet: Features the largest number of connected devices.

    • Intranet: Minimal number of devices are connected.

    • Extranet: The number of connected devices is higher/more comparable with an Intranet but smaller than the Internet.

  • Point of Difference: Owner

    • Internet: No single owner.

    • Intranet: Owned by a single organization.

    • Extranet: Owned by a single or multiple organizations.

  • Point of Difference: Purpose of the Network

    • Internet: To share information throughout the entire world.

    • Intranet: To share information throughout the specific organization.

    • Extranet: To share information between internal members and external members; it utilizes the public network to share info with suppliers and vendors.

  • Point of Difference: Security

    • Internet: Security is dependent on the individual user of the connected device.

    • Intranet: Security is strictly enforced via a firewall.

    • Extranet: Security is enforced via a firewall that separates the internet from the extranet segment.

Conceptual Scope Summary

  • The Internet: Creates connections among computers around the entire world (Public sphere).

  • The Extranet: Creates connections beyond or outside an organization to suppliers and customers.

  • The Intranet: Creates connections strictly within or inside an organization for employees.