Apollo Server Subscriptions not working - mysql

Question

I've made a GraphQL backend using Apollo Server, Sequelize (for the ORM), MySQL (DB) and Express (Web Server).
I have also added subscriptions, which the problem is there.
I can't even reach the WS endpoint using a websocket tester.
Can someone review my code and tell me what the problem is? I looked in the docs, other stackoverflow questions and I can't find any solution.
The code: https://github.com/seklyza/graphqlsubscriptions
Thanks for everyone

Answer 1

I think you have to make 2 Servers one for the app which uses the express server and one for the websocket. It could look like this.
GraphQL express server:
...
graphQLServer = express();
const GRAPHQL_PORT = 4000;
graphQLServer.use('/graphql', bodyParser.json(), graphqlExpress((request) => {
return {
schema: executableSchema,
};
}));
graphQLServer.use('/graphiql', graphiqlExpress({
endpointURL: '/graphql',
}));
graphQLServer.listen(GRAPHQL_PORT, () => {
console.log(`GraphQL Server is now running on http://localhost:${GRAPHQL_PORT}/graphql`); // eslint-disable-line no-console
});
...
websocket server for subscriptions:
...
const WS_PORT = 8080;
const websocketServer = createServer((request, response) => {
response.writeHead(404);
response.end();
});
websocketServer.listen(WS_PORT, () => console.log( // eslint-disable-line no-console
`Websocket Server is now running on http://localhost:${WS_PORT}`
));
const subscriptionManager = new SubscriptionManager({
schema: executableSchema,
pubsub: pubsub,
setupFunctions: { /* your subscription channels */ },
});
subscriptionServer = new SubscriptionServer({
subscriptionManager: subscriptionManager
}, {
server: websocketServer,
path: '/',
});
...
And you need some sort of publication subscription service, we use pubSub. It is included in the server file and looks like this:
import {
PubSub
} from 'graphql-subscriptions';
const pubsub = new PubSub();
export {
pubsub
};

Answer 2

You can create some web socket server wrapper which implements start method which will be responsible for creating and running the WSServer, as well as it will create a SubscriptionServer with use of SubscriptionManager
// in subscription.js
import { PubSub, SubscriptionManager } from 'graphql-subscriptions';
const pubSub = new PubSub();
let subscriptionManagerOptions = {
schema: schema, // this is your graphql schema
setupFunctions: {
// here come your setup functions
},
pubSub: pubSub
};
const subscriptionManager = new SubscriptionManager(subscriptionManagerOptions);
export { pubSub, subscriptionManager };
After we have the subscriptionManager created, we can now implement the WSServer
import { createServer } from 'http';
import { SubscriptionServer } from 'subscription-transport-ws';
import { subscriptionManager } from './subscription';
const webSocketServerWrapper = {
start: function(port){
const webSocketServer = createServer((request, response) => {
response.writeHead(404);
response.end();
});
webSocketServer.listen(port, () => {
console.log('WSServer listening on port ' + port);
});
new SubscriptionServer({
subscriptionManager,
onSubscribe: (message, options, request) => {
return Promise.resolve(Object.assign({}, options, {}));
}
}, webSocketServer);
}
};
export default webSocketServerWrapper;
Now you can import the webSocketServerWrapper in the initialisation file like index.js and simply run webSocketServerWrapper.start(PORT);
Here, the second answer which I wrote, you can find a code responsible for creating example subscription and how it should be handled.