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IT 237

Web Technology I

TU BIM · Semester 3 · BIM curriculum effective from 2021

Requirement
required
Credits
3
Study Guide
5 units available

Chapter notes

Authoritative study guide across 5 syllabus units

Open a unit to read its study notes.

Unit 1: Web Essentials· 5 LHs· ~6 marks

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Pass path: Differentiate HTTP vs HTTPS, understand 1-tier vs 2-tier vs 3-tier architecture, and compare static vs dynamic websites. Top path: Deconstruct raw HTTP request/response headers, evaluate DNS resolution pipelines, and analyze Web 1.0 vs 2.0 vs 3.0 paradigm shifts.

Part 1: Core Concepts (2 Marks)

  • ★ Hypertext Transfer Protocol (HTTP): An application-layer, stateless, request-response protocol running over TCP (port 80) that coordinates hypermedia transfer across the World Wide Web.
  • ★ Uniform Resource Locator (URL): A standardized reference address specifying the protocol, domain hostname, optional port, path, and query parameters to locate a web resource (e.g., https://example.com:443/docs/index.html?id=10).
  • ★ Domain Name System (DNS): The hierarchical, distributed naming database that translates human-friendly domain names (e.g., paperkhoj.com) into machine-routable numerical IP addresses (e.g., 104.21.55.2).

Part 2: Structural Frameworks (10 Marks)

1. Multi-Tier Client-Server Web Architectures

3-Tier Web Architecture Framework

3-Tier Web Architecture
3-Tier Web Architecture

When evaluating web architecture tiers:

  1. Tier 1: Presentation Tier (Client Side):
    • Executed inside the client’s web browser.
    • Responsibilities: Rendering HTML structure, CSS layouts, client-side input validation via JavaScript, and user interaction.
  2. Tier 2: Application / Business Logic Tier (Server Side):
    • Web server (Nginx, Apache) combined with application runtime (Node.js, PHP, Python, Java Servlets).
    • Responsibilities: Business logic execution, authentication, authorization, session management, and constructing dynamic HTTP responses.
  3. Tier 3: Data Tier (Storage):
    • Relational (PostgreSQL, MySQL) or NoSQL (MongoDB) databases.
    • Responsibilities: Persistent data storage, data integrity, transaction ACID guarantees, and responding to server SQL/ORM queries.
  4. Core Benefits of 3-Tier over 2-Tier:
    • Enhanced security (database credentials never exposed to client).
    • Horizontal scalability (application and database tiers scale independently).
    • Modular maintainability.

Part 3: Distinction Tables

Static vs. Dynamic Web Sites

Dimension Static Web Sites Dynamic Web Sites
Content Delivery Pre-written HTML/CSS files sent identical to all users Generated on-the-fly by server scripts or client APIs
Database Requirement Zero database required Relies on back-end databases (RDBMS/NoSQL)
User Interactivity Purely read-only; limited to form submissions Rich user accounts, content feeds, personalization
Maintenance Cost Labor-intensive manual page edits Content management systems (CMS) allow instant updates
Server Overhead Extremely low CPU usage; easily cached by CDNs High server processing load per request

Part 4: Worked Problems & Exam Traps

Problem 1 (Standard): HTTP Status Code Classification

Classify and define the meaning of the following standard HTTP response status codes: 200, 301, 400, 403, 404, 500.

  • 200 OK: Request succeeded; requested resource included in response.
  • 301 Moved Permanently: Target resource assigned a new permanent URL.
  • 400 Bad Request: Server cannot process request due to malformed client syntax.
  • 403 Forbidden: Server understands request but refuses to authorize access.
  • 404 Not Found: Server cannot locate the requested resource.
  • 500 Internal Server Error: Generic server error encountered during execution.

Students lose marks here because they describe HTTP as a “stateful” protocol. HTTP is fundamentally stateless; state tracking is achieved artificially via HTTP cookies, web storage, and session tokens.