Looking for code for a server side GraphQL subscription listener

Question

I have been looking high and low for some code that will allow me to register to a GraphQL subscription on the server side and read messages, coming from the external subscripti

Answer 1

Similar implementation as above but in es2015:

var gql_ws = require('ws');  // needed because no native web socket implementation is present
var apollo_link = require("apollo-link");
var apollo_link_ws = require("apollo-link-ws");
var sub_trans_ws = require('subscriptions-transport-ws');

var gql = require('graphql-tag');

var gql_serverConfig = {
  serverUrl: 'https://endpoint',
  subscriptionUrl: 'ws://endpoint/graphql'
};

var gql_client = new sub_trans_ws.SubscriptionClient(gql_serverConfig.subscriptionUrl,{ reconnect: true }, gql_ws);
var gql_link = new apollo_link_ws.WebSocketLink(gql_client);

var query_object = `subscription {
  songUpdate {    
    current {
      time
      metadata{
        id
        artist
        title
      }
    }
  }
}`;

var gql_operation = { query: gql(query_object) };

// execute returns an Observable so it can be subscribed to
apollo_link.execute(gql_link, gql_operation).subscribe({
  next: function next(data) {
    return console.log("received data: " + JSON.stringify(data, null, 2));
  },
  error: function error(_error) {
    return console.log("received error " + _error);
  },
  complete: function complete() {
    return console.log("complete");
  }
});

Answer 2

Figured it out:

const ws = require('ws');
const { WebSocketLink } = require("apollo-link-ws");
const { execute} = require("apollo-link");
const { SubscriptionClient } = require('subscriptions-transport-ws');
const gql = require('graphql-tag');

const serverConfig = {serverUrl:'http://localhost:4000/', subscriptionUrl:'ws://localhost:4000/graphql'};

const client = new SubscriptionClient(serverConfig.subscriptionUrl, {
    reconnect: true
}, ws);

const link = new WebSocketLink(client);

const operation = {
    query: gql`
        subscription eventAdded{
            eventAdded{
                id
                name
                payload
                createdAt
                storedAt
            }
        }`
};

// execute returns an Observable so it can be subscribed to
execute(link, operation).subscribe({
    next: data => console.log(`received data: ${JSON.stringify(data, null, 2)}`),
    error: error => console.log(`received error ${error}`),
    complete: () => console.log(`complete`),
});

console.log(`Listener running at ${new Date().toString()}`);