Resumable stream

This package is inspired by Vercel's take on Resumable Streams used in the Chat SDK, except instead of Redis, this relies on S2 providing a basic implementation to create and resume streams.

Usage

To use this package, you need to create an S2 access token and basin to store all your streams.

1. Sign up here, generate an access token and set it as S2_ACCESS_TOKEN in your env.

2. Create a new basin from the Basins tab with the Create Stream on Append option enabled, and set it as S2_BASIN in your env.

The incoming stream is batched and the batch size can be changed by setting S2_BATCH_SIZE.

To integrate this package with the Chat SDK, checkout the following changes here.

import { createResumableStreamContext } from "resumable-stream";
import { after } from "next/server";

const streamContext = createResumableStreamContext({
  waitUntil: after,  
});

export async function POST(req: NextRequest, { params }: { params: Promise<{ streamId: string }> }) {
  const { streamId } = await params;
  const inputStream = makeTestStream();
  const stream = await streamContext.createNewResumableStream(
    streamId,
    inputStream,
  );
  return new Response(stream, {
    headers: {
      "Content-Type": "text/event-stream",
    },
  });
}

export async function GET(req: NextRequest, { params }: { params: Promise<{ streamId: string }> }) {
  const { streamId } = await params;  
  const stream = await streamContext.resumeExistingStream(
    streamId    
  );
  if (!stream) {
    return new Response("Stream is already done", {
      status: 422,
    });
  }
  return new Response(stream, {
    headers: {
      "Content-Type": "text/event-stream",
    },
  });
}

Type docs

Type docs