Subscriptions not working

[DregondRahl]

import { PubSub } from 'graphql-subscriptions';

const pubsub = new PubSub();

const roots = {
  query: {
    hello: () => {
      pubsub.publish('TEST', { greetings: 'Morning' });
    },
  },
  subscription: {
    greetings: () => pubsub.asyncIterator('TEST'),
  },
};```



If i run something like that I get an error 

"description": "Error: Cannot perform I/O on behalf of a different request. I/O objects (such as streams, request/response bodies, and others) created in the context of one request handler cannot be accessed from a different request's handler. This is a limitation of Cloudflare Workers which allows us to improve overall performance.",

[enisdenjo]

How is your issue related or caused by graphql-ws?

[DregondRahl]

I'm using "graph-ws" with the "cloudflare-worker-graphql-ws-template". By adding 'graphql-subscriptions' I'm able to access PubSub for subscriptions.

When I use the code with Cloudflare Websockets I get the I/O error, however if I run it locally with "ws" it works fine. I'm trying to figure out whats happening in this area that could be causing this problem https://github.com/enisdenjo/cloudflare-worker-graphql-ws-template/blob/master/index.js#L30

import { makeServer, MessageType, stringifyMessage } from 'graphql-ws';
import { PubSub } from 'graphql-subscriptions';
import { buildSchema } from 'graphql';
import graphiql from './graphiql';

export const pubsub = new PubSub();

// construct a schema, using GraphQL schema language
const schema = buildSchema(`
  type Query {
    hello: String
  }
  type Subscription {
    greetings: String
  }
`);

// the roots provide resolvers for each GraphQL operation
const roots = {
  query: {
    hello: () => {
      pubsub.publish('TEST', { greetings: "Morning" });
    },
  },
  subscription: {
    greetings: () => pubsub.asyncIterator(['TEST']),
  },
};

// use cloudflare server websocket for graphql-ws
function useWebsocket(socket, request, protocol) {
  const server = makeServer({ schema, roots });
  socket.accept();

  let pinger, pongWait;
  function ping() {
    if (socket.readyState === socket.OPEN) {
      socket.send(stringifyMessage({ type: MessageType.Ping }));
      pongWait = setTimeout(() => {
        clearInterval(pinger);
        socket.close();
      }, 6000);
    }
  }
  pinger = setInterval(() => ping(), 12000);
  const closed = server.opened(
    {
      protocol, // will be validated
      send: (data) => socket.send(data),
      close: (code, reason) => socket.close(code, reason),
      onMessage: (cb) =>
        socket.addEventListener('message', async (event) => {
          try {
            await cb(event.data);
          } catch (err) {
            socket.close(1011, err.message);
          }
        }),
      onPong: () => clearTimeout(pongWait),
    },
    { socket, request },
  );

  socket.addEventListener('close', (code, reason) => {
    clearTimeout(pongWait);
    clearInterval(pinger);
    closed(code, reason);
  });
}

function handleRequest(request) {
  const url = new URL(request.url);
  switch (url.pathname) {
    case '/':
      return graphiql();
    case '/graphql':
      const upgradeHeader = request.headers.get('Upgrade');
      if (upgradeHeader !== 'websocket') {
        return new Response('Expected websocket', { status: 400 });
      }

      const [client, server] = Object.values(new WebSocketPair());
      const subprotocol = request.headers.get('Sec-WebSocket-Protocol');

      useWebsocket(server, request, subprotocol);

      return new Response(null, {
        status: 101,
        webSocket: client,
        headers: {
          'Sec-WebSocket-Protocol': subprotocol,
        },
      });
    default:
      return new Response('Not found', { status: 404 });
  }
}

addEventListener('fetch', (event) => {
  event.respondWith(handleRequest(event.request));
});

[enisdenjo]

The error you're sharing is unrelated and I don't think it has anything to do with graphql-ws.

Seems more like a problem with your setup or graphql-subscriptions influenced by CloudFlare workers.

Sorry, but if the error is not caused by graphql-ws, I cannot help you.

[DregondRahl]

Thanks, I'll check into it from that end.