When this subject was taught, e-commerce meant early online shops and credit-card payments. Today it covers UPI, marketplaces such as Amazon and Flipkart, SaaS subscriptions and mobile apps, and India has become one of the world’s largest digital payment markets. The underlying ideas are the same: how businesses transact over networks, how money moves, how the transaction is made safe and what the law says. This article revisits the five units of the JNTUK course.
Unit 1: Introduction, models and architecture
Electronic commerce is buying, selling and exchanging products, services and information over computer networks. E-business is broader, covering internal processes too. Benefits: 24 × 7 reach, lower costs, personalisation, faster delivery of digital goods. Limits: trust, security, logistics and the digital divide.
Business models
| Model | Between | Examples |
|---|---|---|
| B2C | Business to consumer | Amazon, Myntra, Swiggy |
| B2B | Business to business | Procurement portals, IndiaMART, supply platforms |
| C2C | Consumer to consumer | OLX, marketplaces for used goods |
| C2B | Consumer to business | Freelance platforms, crowd-sourced designs |
| B2G / G2C | With government | e-tendering, GST portal, passport and tax services |
Revenue models include sales, commission (marketplaces), advertising, subscription (SaaS, OTT), freemium, affiliate and transaction fees. Older terms covered: brick-and-mortar, click-and-mortar and pure-play businesses.
Architecture
A typical e-commerce system has layers:
| Layer | Role |
|---|---|
| Presentation | Web and mobile front end |
| Application / business logic | Catalogue, cart, order, pricing, user accounts, recommendation |
| Data | Product, order and customer databases |
| Integration | Payment gateway, shipping, ERP, tax, email and SMS |
Key components are the product catalogue, shopping cart, checkout, search, payment, order management and customer service. The network infrastructure covers the Internet, intranets, extranets, web servers, CDNs and cloud hosting.
Today: a retailer’s platform is a set of micro-services behind an API gateway: catalogue, cart, orders, payments, inventory, notifications, search. High-traffic sale days (festival sales) are why autoscaling, caching, queues and load tests matter so much in this domain.
Unit 2: Electronic payment systems
Types of payment
| Type | How it works | Examples |
|---|---|---|
| Cards | Credit, debit and prepaid cards over a gateway | Visa, Mastercard, RuPay |
| Net banking | Direct bank transfer through the bank’s site | Bank portals |
| Digital wallets | Stored value in an app | Paytm, PhonePe wallet, Amazon Pay |
| UPI | Instant bank-to-bank transfer using a virtual payment address | PhonePe, Google Pay, BHIM |
| Electronic fund transfer | NEFT, RTGS, IMPS | Bank transfers |
| Cash on delivery (COD) | Pay when the goods arrive | Common in India |
| Electronic cash and micropayments | Small-value digital tokens | Early e-cash, in-app credits |
| Cryptocurrency | Blockchain-based tokens | Bitcoin (regulated or restricted in many countries) |
How a card payment works
The parties are the customer, merchant, acquirer (the merchant’s bank), issuer (the customer’s bank), the card network and a payment gateway.
- The customer enters card details on the gateway’s secure page.
- The gateway sends an authorisation request through the acquirer and network to the issuer.
- The issuer checks funds and fraud rules, and approves or declines.
- The merchant ships the goods; clearing and settlement move the money to the merchant, minus fees.
The payment gateway (Razorpay, PayU, Stripe, CCAvenue) connects the merchant to this chain. The Payment Card Industry Data Security Standard (PCI DSS) governs how card data is stored. Tokenisation replaces the card number with a token so that merchants no longer store the card.
UPI
The Unified Payments Interface, built by NPCI, sits on top of IMPS. Users link bank accounts to a VPA (such as name@bank), and a payment is authorised with a UPI PIN. It is interoperable, instant and free for users, and it works through QR codes, collect requests and apps.
Today: DevOps teams integrate payment gateways through APIs and webhooks (the gateway calls your server on success or failure), so idempotent handlers, retries and reconciliation jobs are common work. Payment outages and slow callbacks are some of the most critical incidents in e-commerce.
Unit 3: Security and the legal framework
Threats
| Threat | Example |
|---|---|
| Phishing and spoofing | Fake sites and emails that steal credentials |
| Card fraud | Stolen card data, card-not-present fraud |
| Man-in-the-middle | Intercepting traffic on an insecure network |
| Denial of service | Flooding a site to stop sales |
| Data breach, malware | Theft of customer data |
| Fake reviews, return fraud, account takeover | Abuse of platform rules |
Security tools
| Need | Mechanism |
|---|---|
| Confidentiality | Encryption: TLS/SSL (HTTPS), AES, RSA |
| Integrity | Hashes and message authentication codes |
| Authentication | Passwords, OTP, multi-factor, digital certificates |
| Non-repudiation | Digital signatures |
| Secure payments | 3-D Secure (OTP at checkout), tokenisation, SET (older standard) |
| Network defence | Firewalls, WAF, intrusion detection, DDoS protection |
A Public Key Infrastructure (PKI) issues certificates through certificate authorities, so that a browser can verify the site’s identity.
The legal framework in India
| Law | Relevance |
|---|---|
| Information Technology Act, 2000 | Legal recognition of electronic records and digital signatures; defines cyber offences; the base law for e-commerce |
| Consumer Protection Act, 2019 and E-Commerce Rules, 2020 | Consumer rights, seller disclosures, grievance redressal |
| Digital Personal Data Protection Act, 2023 | Consent and handling of personal data |
| Indian Contract Act, 1872 | Online contracts are valid contracts |
| Intellectual property and taxation | Copyright, trademarks, GST applied to online sales |
Other legal topics: domain-name disputes, cyber crime and jurisdiction across borders.
Today: engineers meet this as PCI scope, data-retention and consent requirements, audit logs and encryption at rest and in transit. A WAF and bot protection in front of a store, and certificate renewal automation, are standard parts of the platform.
Unit 4: Supply chain, CRM and marketing
Supply chain management (SCM)
The supply chain runs from supplier to manufacturer to distributor to retailer to customer. SCM coordinates materials, information and money. E-commerce adds real-time inventory, order tracking and automated replenishment.
| Concept | Meaning |
|---|---|
| ERP | Enterprise resource planning integrates finance, stock, HR and orders |
| EDI | Electronic data interchange: standard business documents between companies |
| Just-in-time | Stock arrives as needed, to cut inventory cost |
| Warehousing and fulfilment | Picking, packing, shipping, last-mile delivery |
| Reverse logistics | Returns and refunds |
Customer relationship management (CRM)
CRM stores customer history and uses it to serve and retain customers: segmentation, support tickets, loyalty programmes, personalisation, recommendation engines. Tools include Salesforce and Zoho.
Online marketing
| Channel | Idea |
|---|---|
| SEO | Improve organic search ranking |
| SEM / pay-per-click | Paid search ads |
| Email and SMS | Direct campaigns |
| Social media and influencers | Community and trust |
| Affiliate marketing | Commission on referred sales |
| Content marketing | Useful articles, videos |
| Analytics | Funnels, conversion rate, cart abandonment, A/B tests |
Today: a catalogue sync from an ERP, inventory events on Kafka, and a data warehouse for analytics are the technical side of this unit. The metrics (conversion rate, average order value, cart abandonment) drive the A/B tests that engineers run.
Unit 5: Mobile commerce, marketplaces and new trends
Mobile commerce (m-commerce)
Commerce done through phones and tablets: apps, mobile web, QR payments, NFC tap-to-pay, SMS and push notifications, and location-based services. India’s mobile-first users, cheap data and UPI made m-commerce the main channel. Constraints are small screens, variable networks and device security.
Marketplaces and platforms
A marketplace (Amazon, Flipkart, Meesho) lists many sellers; an aggregator (Swiggy, Uber) matches demand and supply; a D2C brand sells directly. The government’s ONDC (Open Network for Digital Commerce) aims to make buyer apps and seller apps interoperable, as UPI did for payments.
Newer trends
| Trend | Idea |
|---|---|
| Quick commerce | Delivery in minutes from local dark stores |
| Social and live commerce | Buying through social media and live streams |
| AI-driven personalisation, chatbots, search | Recommendations and customer support |
| AR/VR try-on | Visualise products |
| Subscription and SaaS models | Recurring revenue |
| Blockchain | Traceability, smart contracts |
| Voice commerce | Ordering by voice assistant |
Challenges
Trust and fraud, logistics cost, returns, competition, regulation, and the digital divide (language, connectivity and skills).
Today: the architecture needed for these trends is the same one cloud teams already run: event streaming for inventory and delivery tracking, machine-learning services for recommendations and fraud detection, CDNs for mobile speed and Kubernetes for scaling services during sales.
One-minute recap
| Unit | Key idea | You meet it in |
|---|---|---|
| 1. Models and architecture | B2C, B2B, C2C; catalogue, cart, order, payment layers | Micro-services for retail, autoscaling for sales |
| 2. Payments | Cards via acquirer, issuer, gateway; UPI; tokenisation | Gateway APIs, webhooks, reconciliation |
| 3. Security and law | TLS, PKI, 3-D Secure; IT Act, E-Commerce Rules, DPDP Act | PCI scope, audit logs, WAF, consent |
| 4. Supply chain, CRM, marketing | ERP, EDI, last mile, SEO, conversion rate | Inventory events, analytics, A/B tests |
| 5. Mobile and trends | m-commerce, marketplaces, ONDC, quick commerce | Mobile-first backends, personalisation, scale |
Next in Engineering Revisited: Human Computer Interaction.
Written by Claude, Anthropic’s AI assistant, as part of Engineering Revisited, a quick refresher of the B.Tech subjects one at a time.