Step By Step Guide
Step 1: Understand the Problem
Ask Clarifying Questions: Start by asking questions to fully understand the requirements and scope of the problem. This shows your interviewer that you are thorough and detail-oriented.
Example: Are we designing this system for a global audience or a specific region?
Step 2: Define the Scope and Requirements
Functional Requirements: Identify the core functionalities the system must have.
Example: The system should handle user authentication, data storage, and real-time updates.
Non-Functional Requirements: Determine performance, scalability, and reliability needs.
Example: The system should support up to 1 million concurrent users with 99.99% uptime.
Step 3: Envelope Calculations
Estimate Load: Calculate the expected load on the system based on the number of users and their interactions.
Example: Assume 1 million daily active users, each making an average of 10 requests per day, resulting in 10 million requests daily.
Data Storage Requirements: Estimate how much data will be stored and processed.
Example: If each request generates 1 KB of data, we need to store approximately 10 GB of data daily.
Bandwidth Requirements: Calculate the bandwidth needed to handle data transfer.
Example: With each request/response being 1 KB, we need a bandwidth of around 10 GB per day.
Step 4: High-Level System Design
Draw the Architecture: Create a high-level diagram of the system architecture. Include key components like databases, servers, and external services.
Example: We'll use a microservices architecture with load balancers, a distributed database, and a CDN for content delivery.
Explain Your Choices: Justify the technologies and patterns you’ve chosen.
Example: We’re using microservices for better scalability and maintainability.
Step 5: Detailed Component Design
Focus on Key Components: Dive deeper into the design of crucial parts of the system.
Example: For user authentication, we’ll implement OAuth 2.0 with JWT tokens.
Data Models: Define the data schema and storage mechanisms.
Example: We'll use a relational database for transactional data and a NoSQL database for user sessions.
Step 6: Scalability and Reliability
Handling Traffic: Discuss strategies for scaling the system.
Example: We'll use auto-scaling groups and a global load balancer to handle traffic spikes.
Fault Tolerance: Explain how the system will handle failures.
Example: We’ll implement redundancy with multiple data centers and use a backup and restore strategy for data recovery.
Step 7: Security Considerations
Data Protection: Talk about securing data in transit and at rest.
Example: We'll use SSL/TLS for data in transit and AES encryption for data at rest.
Access Controls: Describe how you'll manage user permissions and roles.
Example: We'll implement role-based access control (RBAC) to restrict access based on user roles.
Step 8: Monitoring and Maintenance
Monitoring Tools: Explain how you’ll monitor the system's health and performance.
Example: We'll use Prometheus and Grafana for monitoring metrics and setting up alerts.
Maintenance Plan: Discuss how you’ll handle updates and maintenance without downtime.
Example: We'll use blue-green deployment for zero-downtime updates.
Step 9: Trade-offs and Considerations
Discuss Alternatives: Mention any alternative solutions and why you chose your approach.
Example: We considered using a monolithic architecture but opted for microservices for better scalability.
Acknowledge Trade-offs: Be honest about the trade-offs of your design.
Example: While microservices offer scalability, they also introduce complexity in terms of communication and monitoring.
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