edge-computing-patterns

Edge Computing Patterns

Overview

Edge computing runs code closer to users worldwide, reducing latency from seconds to milliseconds. This skill covers Cloudflare Workers, Vercel Edge Functions, and Deno Deploy patterns for building globally distributed applications.

When to use this skill:

• Global applications requiring <50ms latency
• Authentication/authorization at the edge
• A/B testing and feature flags
• Geo-routing and localization
• API rate limiting and DDoS protection
• Transforming responses (image optimization, HTML rewriting)

Platform Comparison

Feature	Cloudflare Workers	Vercel Edge	Deno Deploy
Cold Start	<1ms	<10ms	<10ms
Locations	300+	100+	35+
Runtime	V8 Isolates	V8 Isolates	Deno
Max Duration	30s (paid: unlimited)	25s	50ms-5min
Free Tier	100k req/day	100k req/month	100k req/month

Cloudflare Workers

// worker.ts
export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const url = new URL(request.url)

    // Geo-routing
    const country = request.cf?.country || 'US'

    if (url.pathname === '/api/hello') {
      return new Response(JSON.stringify({
        message: `Hello from ${country}!`
      }), {
        headers: { 'Content-Type': 'application/json' }
      })
    }

    // Cache API
    const cache = caches.default
    let response = await cache.match(request)

    if (!response) {
      response = await fetch(request)
      // Cache for 1 hour
      response = new Response(response.body, response)
      response.headers.set('Cache-Control', 'max-age=3600')
      await cache.put(request, response.clone())
    }

    return response
  }
}

// Durable Objects for stateful edge
export class Counter {
  private state: DurableObjectState
  private count = 0

  constructor(state: DurableObjectState) {
    this.state = state
  }

  async fetch(request: Request) {
    const url = new URL(request.url)

    if (url.pathname === '/increment') {
      this.count++
      await this.state.storage.put('count', this.count)
    }

    return new Response(JSON.stringify({ count: this.count }))
  }
}