Principle:Openai Openai node Server To Client Stream Proxying
| Knowledge Sources | |
|---|---|
| Domains | Streaming, Server_Architecture |
| Last Updated | 2026-02-15 00:00 GMT |
Overview
A principle for converting server-side SDK stream objects into Web Streams API ReadableStreams that can be sent as HTTP response bodies to browser clients.
Description
Server-to-Client Stream Proxying enables real-time streaming of OpenAI API responses from a backend server to a frontend browser. The server calls the OpenAI API with streaming enabled, then converts the SDK's stream object into a standard ReadableStream that can be piped directly as the HTTP response body.
This pattern is essential for security: the API key stays on the server, while the client receives real-time updates. The conversion preserves the streaming semantics — each chunk is a newline-delimited JSON string encoded as UTF-8 bytes.
Usage
Use this principle when building web applications where the backend proxies OpenAI streaming responses to the browser. Works with Express, Next.js, raw Node.js HTTP, and any framework that accepts a ReadableStream as a response body.
Theoretical Basis
Stream proxying follows a Bridge Pattern between two streaming interfaces:
// Server-side (Node.js):
// 1. Call OpenAI with streaming
stream = client.chat.completions.stream({ model, messages })
// 2. Convert SDK stream to Web ReadableStream
readableStream = stream.toReadableStream()
// 3. Send as HTTP response body
response.body = readableStream
response.headers['Content-Type'] = 'text/event-stream'
// The ReadableStream produces:
// - Each chunk: JSON.stringify(chatCompletionChunk) + '\n'
// - Encoded as UTF-8 bytes