System Architecture and Network Considerations Study Notes (copy)
Systems Analysis and Design (SAD) & System Architecture Fundamentals
System Architecture in SAD: The overall blueprint defining interactions between hardware, software, and network components to carry out information system functions designed during the Systems Analysis and Design process.
Importance in System Design:
Improves overall system performance and security.
Simplifies system maintenance and troubleshooting.
Increases system reliability and fault tolerance.
Supports scalability for future organizational expansion.
Core Components of System Architecture
Client: Device or application used by end users to access the system (e.g., desktop, laptop, smartphone, tablet, web browser like Google Chrome).
Server: Provides centralized services, processes client requests, and manages shared resources (e.g., Web Server, Database Server, File Server, Application Server).
Database: Stores all persistent system information (e.g., Student Records, Employee Records, Product Inventory, Customer Information).
Application: Contains core business logic processing user requests (e.g., validates login credentials, checks prerequisites, computes tuition, saves enrollment, generates confirmation).
Architecture Types and Styles
One-Tier Architecture: All components exist on a single computer (e.g., Microsoft Access database running locally on one PC).
Two-Tier Architecture: Clients communicate directly with a central database server (e.g., a desktop cashier application connected to a MySQL server).
Three-Tier Architecture: The standard model in modern enterprise systems analysis and design, separating system responsibilities into distinct layers:
Presentation Layer: Displays information and captures user input (e.g., Login page, Dashboard, Registration Form).
Application Layer: Processes user requests and business logic (e.g., Verifying login credentials, Calculating grades, Processing payments, Validating enrollment).
Data Layer: Manages and stores system data (e.g., Student Database, Employee Database, Sales Database).
Architectural Styles:
Monolithic: Single, tightly integrated unified application.
Microservices: Application broken down into small, loosely coupled, independent services.
Client-Server: Clients request resources and services from a central server.
Event-Driven: Systems react to real-time events or state changes using message brokers or queues.
Layered (n-tier): Organized into horizontal stacked layers interacting only with adjacent layers.
Peer-to-Peer: Decentralized network structure where each node acts as both client and server.
Network Architecture & Infrastructure in SAD
Network Considerations: Planning and designing device communications to ensure secure, efficient, and reliable system access.
Network Objectives: Ensure reliable communication, fast transmission rates, secure data access, high availability, and future growth adaptability.
Key Network Components:
Client Devices: End-user hardware such as desktops, laptops, and smartphones.
Servers: Dedicated host devices (Web Server, Database Server, Mail Server).
Network Devices:
Router: Directs traffic and connects different networks.
Switch: Connects devices within the same local network.
Wireless Access Point: Enables wireless (Wi-Fi) network connectivity.
Firewall: Filters and secures incoming/outgoing network traffic.
Communication Media: Ethernet cabling, fiber optic cables, Wi-Fi, and cellular networks.
Network Topologies and Types
Topologies:
Bus Topology: Devices connected sequentially along a single backbone cable.
Star Topology: Devices connected to a central hub or switch.
Ring Topology: Devices connected in a closed circular loop structure.
Mesh Topology: Direct redundant connections established between every device.
Tree Topology: Hierarchical branching structure stemming from a central root node.
Hybrid Topology: Combination of two or more distinct network topologies.
Common Network Types:
LAN (Local Area Network): Covers a small geographical area (e.g., school computer laboratory).
WAN (Wide Area Network): Connects multiple geographic locations across large distances.
Internet: Global public network used to access distributed online systems.
OSI Model & Protocols
Protocols: Standardized rules governing data communication across network systems (e.g., HTTP, TCP, IP).
OSI Model Layers:
Layer (Application): Network services provided directly to end-user applications (HTTP, FTP, SMTP, DNS).
Layer (Presentation): Data format translation, encryption, and compression (SSL/TLS, JPEG, MPEG).
Layer (Session): Controls and manages communication sessions between applications (NetBIOS, RPC).
Layer (Transport): End-to-end reliable data transfer, error detection, and flow control (TCP, UDP).
Layer (Network): Logical addressing and packet routing across networks (IP, ICMP, IPsec).
Layer (Data Link): Physical addressing and frame delivery within a local network segment (MAC addresses, Ethernet, PPP).
Layer (Physical): Physical transmission of unformatted raw bits over a physical medium (Cables, Hubs, Switches, Fiber optics).
Network Design Criteria & System Interaction
Performance: High data transfer rates (bandwidth) coupled with low latency.
Scalability: System capacity to handle operational growth (e.g., expanding capacity from to concurrent users).
Reliability & Availability: System remains continuously accessible (e.g., availability) using backup servers and redundant network pathways.
Security: Defense mechanisms including firewalls, VPNs, antivirus, encryption, user authentication, and multi-factor authentication (MFA).
Backup & Disaster Recovery: Scheduled database backups, off-site data storage, and business continuity planning.
Interaction Flow: User → Client Device → Network Infrastructure → Web/Application Server → Database Server → Stored Data
Here is a guide on how to present and report the System Architecture section using the What, Why, and How framework, along with a real-life example.
Presentation Outline & Script
1. WHAT is System Architecture in SAD?
Explanation: System Architecture is the overall structural blueprint of an information system. It defines how hardware, software, data, and network components interact to make the system work.
Key Point to State: "Think of it as the master blueprint designed during Systems Analysis and Design to ensure all system components communicate efficiently."
2. WHY is System Architecture Important?
Explanation: Without a proper architecture, systems become slow, insecure, and hard to maintain.
Key Benefits to Mention:
Performance & Security: Optimizes processing speed and protects sensitive data.
Scalability: Allows the system to handle thousands of new users as the organization grows.
Reliability & Maintenance: Makes troubleshooting easier and prevents whole-system failures.
3. HOW is System Architecture Implemented?
Explanation: It is designed by breaking down system functions into structured layers and core components:
Client Layer: User interfaces (e.g., mobile apps, web browsers).
Application Layer: Business rules and logic processing.
Data Layer: Centralized databases storing persistent records.
Architectural Style: Choosing patterns like 3-Tier, Microservices, or Client-Server.
Real-Life Example: Online University Enrollment System
WHAT: The architectural blueprint connecting a student's smartphone to the university's central enrollment servers.
WHY: During enrollment week, thousands of students register simultaneously. Proper architecture prevents site crashes, protects grade privacy, and processes tuition correctly.
HOW it works in practice:
Presentation Layer (Client): The student opens Google Chrome and submits a course schedule form.
Application Layer (Server): The server processes the request by checking if prerequisites are met, calculating tuition fees, and validating course capacity.
Data Layer (Database): The database saves the confirmed schedule and updates student account records.