Study Info

This is your Ultimate Exam Study Guide, synthesized from your five lecture decks, the professor's review transcript, and the four past quizzes.

I have organized this into three distinct sections: Conceptual Deep Dives (for Short Answer), Technical Specs (for MCQs and Tiny Code), and the E-Commerce Architecture Map.

🏛 PART 1: The "Descriptive" Mastery (Lectures 1 & 2)

Focus on these for the short-answer/descriptive portion. The professor expects you to explain "How" and "Why."

1. Networking & Data Transmission

* Packet Switching: Messages are divided into small packets and sent independently.

* Advantage: Line efficiency (multiple users can share the same line) and "Store and Forward" capability (packets are stored until the next link is clear).

* Security Risk: Packets can be intercepted or misrouted.

* TCP/IP vs. OSI: * The Internet (Network) Layer is responsible for addressing via IP.

* QUIC (Quick UDP): A protocol designed to reduce latency while maintaining security. It is vital for e-commerce performance.

* DNS (Domain Name System): Created because the old host.txt files were not scalable.

* Vulnerability: DNS Spoofing/Cache Poisoning allows attackers to redirect your traffic to a malicious server.

2. Architecture & Performance

* N-Tier Architecture: The "Gold Standard" for secure e-commerce.

* Why it's better: Provides Firewall separation, Tier isolation, and Minimized direct access to the data layer.

* Disadvantage: Can lead to slower performance due to increased network overhead between tiers.

* Scaling: * Vertical: Adding more RAM/CPU to a single server.

* Horizontal: Adding more server units to a pool.

* Web Proxies & Caching: * Proxy: Acts as a gateway/firewall to control traffic and improve security.

* Caching: Improves performance by reducing latency and bandwidth usage.

* Conditional GET: A request that asks the server to send the page only if it has changed, saving bandwidth.

💻 PART 2: Technical Specs (Lectures 3 - 5)

Focus on these for MCQs and the "Tiny Code" (SQL/PHP/HTML) portion.

1. Web Languages (HTML & CSS)

* HTML: An open standard by the W3C.

* Tags to Know:

* <ol>: Ordered list (numbered) | <ul>: Unordered list (bulleted).

* <li>: List item.

* <br>: Line break (a void element - no closing tag).

* <a>: Hyperlink (requires href attribute).

* Syntax: Most whitespace is ignored or collapsed by the browser.

* Invisible Tables: Used specifically to position text into columns.

2. Server-Side Logic (PHP)

* Basics: PHP is server-side; it is executed on the server, not the browser.

* Syntax Rules: * Every statement must end with a semicolon (;).

* unlink(): The function used to delete a file.

* echo or print(): Functions to output text.

* Data Types: Character is NOT a valid PHP data type (use String).

* Security: POST is more secure than GET for sensitive data.

3. Databases (SQL & XML)

* Relational Model: Data is organized into tables called Relations.

* Attribute: A column.

* Tuple: A row.

* SQL Writing (Potential Short Answer): * SELECT * FROM Products WHERE Price > 50;

* CREATE TABLE Users (UserID int, Username varchar(255));

* XML: Uses tags like HTML but all tags must close and be nested properly.

* SAX Parser: Event-based (serial).

* DOM Parser: Tree-based (memory-intensive).

🖼 PART 3: E-Commerce Architecture Infographic

Use this visual logic to understand how the components tie together for the exam.

The Workflow Breakdown:

* THE CLIENT (Browser):

* Languages: HTML (Structure), CSS (Style), JavaScript (Interactivity).

* Communication: Sends HTTP GET/POST requests.

* State: Uses Cookies (stored in RAM/Disk) to solve HTTP's "statelessness".

* THE PRESENTATION TIER (Web Server/Proxy):

* Hardware: Load Balancing Switch sits between Client and Server.

* Role: Web Proxy caches content to reduce latency and acts as a firewall.

* THE BUSINESS LOGIC TIER (Application Server):

* Language: PHP (Server-side scripting).

* Role: Processes logic (e.g., calculating totals, checking login credentials).

* Security: This tier is isolated from the data layer by a firewall.

* THE DATA TIER (Database):

* Language: SQL (Queries) and XML/JSON (Data exchange).

* Role: Permanent storage for products, users, and orders.

* Structure: Relational model using Attributes (columns) and Tuples (rows).

🚨 Quick-Reference: HTTP Status Codes

* 200 OK: Success.

* 307 Temporary Redirect: Resource moved.

* 400 Bad Request: Malformed syntax.

* 404 Not Found: Client error (page doesn't exist).

* 5xx: Server Errors (Internal issues).