HTTP server: Node.js streams

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Code ported from Node.js often produces Node streams: file streams, database cursors, archive generators. This example serves them, both from a node:http server and from Deno.serve.

import { createServer } from "node:http";
import { Readable } from "node:stream";

The node:http API works in Deno as-is. Piping a Readable into the response streams it to the client.

const nodeServer = createServer((_req, res) => {
  const stream = Readable.from(["Hello ", "from ", "node:http\n"]);
  res.setHeader("content-type", "text/plain");
  stream.pipe(res);
});
nodeServer.listen(8001);

With Deno.serve, convert the Node stream to a web ReadableStream and use it as the Response body. Web streams carry bytes, so the chunks must be Uint8Arrays: a stream of strings will stall.

const encoder = new TextEncoder();
Deno.serve({ port: 8000 }, () => {
  const stream = Readable.from(
    ["Hello ", "from ", "Deno.serve\n"].map((s) => encoder.encode(s)),
  );
  return new Response(Readable.toWeb(stream) as ReadableStream, {
    headers: { "content-type": "text/plain" },
  });
});

Both servers stream their responses chunk by chunk: curl http://localhost:8001/ Hello from node:http curl http://localhost:8000/ Hello from Deno.serve

Run this example locally using the Deno CLI:

deno run -N -R https://docs.deno.com/examples/scripts/http_server_node_streams.ts

HTTP server: Node.js streams

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