Dashboard/Analytics System

Design a real-time dashboard with charts, widgets, customizable layout, and data visualization.

R - Requirements

Key Questions:

• How many widgets? (5, 10, 20+)
• Real-time updates? (yes, live data)
• Update frequency? (1s, 5s, 30s)
• Customizable layout? (drag & drop)
• Export data? (CSV, PDF)
• Time range filters? (last hour, day, week, month)

Common Answers:

• 10-20 widgets
• Real-time updates (5-30s)
• Drag & drop layout
• Multiple chart types

A - Architecture

Dashboard Data Flow:

Widget Lifecycle:

Architecture Decisions:

• Widget-based architecture (independent components) - Each widget loads independently
• Real-time data (WebSocket/SSE for live updates) - Live metrics, 5-30s updates
• Drag & drop (react-dnd, dnd-kit) - Customizable layout, persist preferences
• Code splitting (lazy load widgets) - Only load widgets user sees

Relevant Content:

• Real-Time Architecture - WebSocket/SSE
• Code Splitting - Widget splitting
• Plugin Architecture - Extensible widgets

D - Data Model

State Management:

• Widget data (time-series, aggregated)
• Filter state (time range, filters)
• Layout state (widget positions, sizes)
• Real-time subscriptions (per widget)

Caching:

• Data aggregation (cache computed metrics)
• Time-series data (cache recent data)
• Layout persistence (localStorage)

Relevant Content:

• Data Fetching Strategies - Real-time, caching
• Persistence Strategies - Layout storage
• Polling and Real-Time Sync - Updates

I - Interface

Features:

• Chart components (line, bar, pie, area)
• Filter controls (time range, dimensions)
• Widget grid (drag & drop)
• Loading states (skeleton, spinners)
• Empty states
• Error states
• Responsive grid

Accessibility:

• Keyboard navigation
• Screen reader support (chart descriptions)
• High contrast mode
• Focus management

Relevant Content:

• Accessibility Patterns - Chart accessibility
• Design Systems - Component consistency

O - Optimizations

Performance:

• Chart rendering (canvas vs SVG, optimize for data size)
• Data pagination (for large time-series)
• Real-time throttling (don't update on every data point)
• Code splitting (lazy load widgets)
• WebSocket connection management (pool, reconnect)

Visual:

• Animation performance (60fps chart updates)
• Paint optimization (reduce repaints)

Relevant Content:

• Animation Performance - Smooth updates
• WebSocket Management - Connection handling
• Code Splitting - Widget splitting
• Paint Optimization - Reduce paint

Implementation Checklist

• Widget-based architecture
• Real-time data (WebSocket/SSE)
• Drag & drop layout
• Chart components (multiple types)
• Time range filters
• Data pagination
• Layout persistence
• Code splitting (lazy load widgets)
• Real-time throttling
• Accessibility (keyboard, screen readers)

Common Pitfalls

❌ Updating on every data point → Performance issues
✅ Throttle updates (5-30s), batch multiple updates

❌ Rendering all data → Slow, memory issues
✅ Paginate time-series, aggregate for charts

❌ No code splitting → Large bundle, slow load
✅ Lazy load widgets, split by widget type

❌ Poor WebSocket management → Connection issues
✅ Connection pooling, reconnect logic, error handling