Unit 8 Session 4: Architectures, Applications, and Cloud Databases | IT 231 BBA Slides

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Unit 8 · Session 4

Architectures, Applications, and Cloud Databases

IT 231: IT and Applications (BBA)

Today's focus

  1. Database System Architectures
  2. Cloud Database

🎯 Learning Objectives

By the end of this session, you will be able to:

  • ✅ Describe 1-tier, 2-tier, and 3-tier database architectures.
  • ✅ Explain why the 3-tier architecture is the standard for modern applications.
  • ✅ Define cloud databases and Database-as-a-Service (DBaaS).
  • ✅ Evaluate the advantages of cloud databases for business.

Database System Architectures

1-Tier Architecture 💻

The database and the application exist on the same physical machine.

  • Direct user interaction with the DB.
  • Pros: Fast, simple.
  • Cons: No network access, poor scalability.

2-Tier Architecture 🖥️ ↔️ 🗄️

A client-server model where the application on the user's machine talks directly to a central database server.

  • Pros: Centralized data, fast development.
  • Cons: Security risks (direct access), limited scalability for concurrent users.

3-Tier Architecture 📱 ↔️ ⚙️ ↔️ 🗄️

Introduces an "Application Server" middle layer between the user and the database.

  1. Presentation: User Interface (Web Browser)
  2. Application: Business Logic (Web Server)
  3. Database: Data Storage (DBMS)

🔎 Follow One Request Through 3 Tiers

You check your exam result on the university website.

  1. Presentation tier (your phone's browser): you type your symbol number and tap "Search".
  2. Application tier (web server): it checks the input is valid and blocks anyone trying to hack the form, then builds a query.
  3. Data tier (database server): it runs SELECT ... WHERE SymbolNo = ... and returns your row.
  4. The application tier formats the result into a web page and sends it back to your phone.

Your phone never talks to the database directly. That's what keeps millions of results safe on result day.

🎬 Client Tier and Logic Tier

Why 3-Tier is the Standard 🏆

  • Security: The user never directly accesses the database.
  • Scalability: You can add more application servers without touching the database.
  • Maintainability: Code is separated logically.

🧪 Activity: 1, 2, or 3 Tier?

1. A shopkeeper's billing software, with the database on the same PC → 1-tier

2. College lab PCs running a desktop attendance app connected straight to a MySQL server in the server room → 2-tier

3. Daraz website → 3-tier

4. A mobile banking app → 3-tier (app → bank's API servers → database)

5. An MS Access file on your personal laptop → 1-tier

🏢 Database Applications in Business

🏦 Finance

Core banking, ATMs, digital wallets, payroll

🛒 Commerce

Point-of-sale (POS), inventory, e-commerce, CRM (customer records)

✈️ Travel

Airline and hotel reservations, ride-sharing

🏥 Health

Patient records, lab results, pharmacy stock

🏛️ Government

Citizenship, passports, land records, tax (PAN), the Nagarik App

🎓 Education

Admissions, exam results, library systems

🌍 Real Case: SABRE, the First Big Booking Database

  • 1950s: American Airlines booked seats with index cards and phone calls. A single booking could take up to 90 minutes.
  • With IBM, they built SABRE, a computer reservation system that was fully running by 1964.
  • Agents across the US could see and book the same seat inventory in seconds.
  • Sabre still exists today, and travel agents worldwide use it, including in Nepal.

It was one of the first large real-time transaction systems, which today we call OLTP.

⚖️ OLTP vs OLAP

OLTP (Online Transaction Processing)OLAP (Online Analytical Processing)
PurposeRun the business, every dayAnalyse the business
Typical actionInsert or update one record, fastRead and summarise millions of records
UsersCustomers, cashiers, tellersManagers, analysts
DataCurrent, detailedHistorical, summarised (a data warehouse)
eSewa exampleYou pay your electricity bill"Which district paid the most bills last Dashain?"

🧪 Activity: OLTP or OLAP?

1. ATM withdrawal OLTP

2. Booking a Buddha Air seat OLTP

3. Adding an item to your Daraz cart OLTP

4. Monthly sales report by province OLAP

5. CEO dashboard showing 5-year trends OLAP

6. Which product sells best in which season? OLAP

Cloud Database

What is a Cloud Database? ☁️

A database that runs on a cloud computing platform (AWS, Azure, Google Cloud) rather than local on-premises servers.

  • Offers the same functionality as traditional DBs.
  • Provides incredible flexibility and remote accessibility.

🎬 Inside a Google Data Centre (2012)

Database-as-a-Service (DBaaS) 🛠️

A managed service where the cloud provider handles the database infrastructure, maintenance, and backups.

  • Zero Maintenance: The provider handles software patches and hardware upgrades.
  • Examples: Amazon RDS, Google Cloud SQL, Firebase.

🤝 Who Does What? On-Premises vs DBaaS

TaskOn-premisesDBaaS (e.g. Amazon RDS)
Buy and repair serversYouProvider
Install and patch the DBMSYouProvider
Automatic backupsYouProvider (you choose the settings)
Design tables and write queriesYouYou
Who can access the dataYouYou

The cloud takes away the hardware work, not your responsibility for your data.

Advantages for Business 📈

  • Cost Efficiency: Pay only for what you use (no hardware costs).
  • Instant Scalability: Add storage or processing power with a single click.
  • Disaster Recovery: Data is automatically replicated across multiple geographic zones.

🧮 Worked Example: Own Server or Cloud?

Illustrative figures for a mid-sized online shop over 3 years:

🏢 Own server

  • Server and storage: Rs 15,00,000 upfront
  • Power, cooling, maintenance: Rs 3,00,000/year
  • Total: 15,00,000 + 9,00,000 = Rs 24,00,000

☁️ DBaaS

  • Rs 40,000/month, nothing upfront
  • 40,000 × 36 = Rs 14,40,000

Your turn: if the shop grows and the bill rises to Rs 70,000/month, which is cheaper? 70,000 × 36 = Rs 25,20,000, so the own server is now cheaper. The cloud is best for starting small or unpredictable demand.

🌍 Real Case: Capital One's Cloud Breach (2019)

  • The US bank Capital One stored customer data on Amazon Web Services (AWS).
  • A firewall that the bank itself had misconfigured let an attacker reach it. Data on about 100 million people in the US and 6 million in Canada was stolen.
  • AWS's own systems were not hacked. US regulators fined Capital One $80 million.

Lesson: Going back to "who does what", access settings are always your job, even in the cloud.

🧪 Activity: Cloud or On-Premises?

1. A new startup app with no idea how many users it will get → Cloud (start small, scale up)

2. An online shop that gets 10× its normal traffic during a Dashain sale → Cloud (pay for the peak only when it happens)

3. A bank whose regulator requires customer data to stay inside the country → On-premises or a local data centre

4. A remote clinic with an unreliable internet connection → A local database, with a cloud backup when it's online

⚡ Key Takeaways

  • 1-, 2- and 3-tier architectures differ in where the screen, the logic and the data live. 3-tier is the standard for web and mobile apps.
  • Databases power applications in every sector, from banking to government.
  • OLTP runs the business, and OLAP analyses it.
  • Cloud databases (DBaaS) remove hardware work, but security and data design are still your responsibility.

💬 Discussion Questions

  1. On exam-result day, the university website often crashes. Which tier is most likely the bottleneck, and how could the cloud help?
  2. Should a Nepali government service such as the Nagarik App store citizens' data with a foreign cloud provider? Give one argument for and one against.
  3. Think of an OLAP question that a momo restaurant chain could ask its sales data.

Exam Practice 📝

Short answer

  1. What is a database application? Explain with an example from a business you use regularly.
  2. What is database system architecture?
  3. What is a cloud database? How does it differ from an on-premises database?
  4. Differentiate between OLTP and OLAP with suitable examples.

Revise the answers in the full notes linked on the last slide.

Image & Video Credits

Images

  • POS machines of Nepal: Nirjal stha, CC BY-SA 4.0, via Wikimedia Commons
  • Overview of a three-tier application: Bartledan (based on a file by Foofy), public domain, via Wikimedia Commons
  • Sanfine International Hospital Ward: Wnkwdy, CC BY-SA 4.0, via Wikimedia Commons
  • Check-in counters at Suvarnabhumi International Airport: Mattes, CC BY-SA 3.0, via Wikimedia Commons
  • OLAP Cube: Konrad Roeder (derivative: Rehua), CC BY-SA 3.0, via Wikimedia Commons
  • Data Center of CMC Telecom: Daoducquan, CC BY-SA 4.0, via Wikimedia Commons
  • HTTPS and padlock in website address bar: Santeri Viinamäki, CC BY-SA 4.0, via Wikimedia Commons

Videos (YouTube)

  • Be A Better Dev, "System Design: What is 3 tier architecture?" (41–123 s)
  • Google, "Explore a Google data center with Street View" (2012, 1–90 s)

Thank You

Questions before we wrap this hour?

Next: Unit 9 · Session 1 — Computer Security and Unauthorized Access

Course Home · Next session

📖 Read the full notes: Database Applications in Business · Database System Architectures · Cloud Database

📖 Related chapter notes

Read first, then revise with this deck: