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Transport Overview

socket-serve supports two transport mechanisms for server-to-client communication:
  1. Server-Sent Events (SSE) - Primary transport
  2. HTTP Polling - Fallback transport

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Server-Sent Events (SSE)

SSE provides a persistent HTTP connection for server-to-client streaming.

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Characteristics

  • Long-lived GET request
  • Unidirectional (server to client only)
  • Automatic browser reconnection
  • Lower latency (50-200ms)
  • Built into modern browsers

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Implementation

// Client establishes SSE connection
const eventSource = new EventSource('/api/socket/events?sessionId=xyz');

eventSource.onmessage = (event) => {
  const message = JSON.parse(event.data);
  handleMessage(message);
};

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Limitations

  • Not supported in all environments
  • Some proxies may buffer SSE
  • Connection count limits per domain

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HTTP Polling

HTTP polling makes periodic requests to check for new messages.

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Characteristics

  • Regular GET requests (1-second interval)
  • Works in all environments
  • Higher latency (~1000ms)
  • More resource-intensive

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Implementation

// Client polls for messages
setInterval(async () => {
  const response = await fetch('/api/socket/poll?sessionId=xyz');
  const messages = await response.json();
  messages.forEach(handleMessage);
}, 1000);

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Transport Selection

The client automatically selects the appropriate transport: 
import { connect } from 'socket-serve/client';

// Default: SSE with automatic fallback to polling
const socket = connect('/api/socket');

// Force polling transport
const socket = connect('/api/socket', { transport: 'polling' });

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Next Steps