Nymph PubSub Server

Powerful object data storage and querying.

The PubSub server provides a WebSocket server that allows Nymph to publish changes and the Nymph Client to subscribe to those changes. You can subscribe to individual entities, entity queries, or UIDs.

Installation

npm install --save @nymphjs/pubsub

Usage

Any Nymph instance will only publish changes if you initialize PubSub publisher before Nymph is used! This step is absolutely required to have a working PubSub system.

import SQLite3Driver from '@nymphjs/driver-sqlite3';
import { Nymph } from '@nymphjs/nymph';
import { PubSub } from '@nymphjs/pubsub';

const pubSubConfig = {
  entries: ['ws://yourpubsubserver.tld:8080/'], // This should be set to your PubSub server URL(s).
};

const nymph = new Nymph(
  {},
  new SQLite3Driver({
    filename: ':memory:', // Put the correct driver/config here.
  }),
);
PubSub.initPublisher(pubSubConfig, nymph);

Now, on your PubSub server, you can use the createServer function to create a new PubSub server using HTTP (without TLS). If you want, this can be done on the same server you use as a REST server, with a different port.

import SQLite3Driver from '@nymphjs/driver-sqlite3';
import { Nymph } from '@nymphjs/nymph';
import createServer, { PubSub } from '@nymphjs/pubsub';

const pubSubConfig = {
  originIsAllowed: (origin) => {
    // Your logic to determine allowed origins goes here.
    return true;
  },
  entries: ['ws://yourpubsubserver.tld:8080/'],
};

const nymph = new Nymph(
  {},
  new SQLite3Driver({
    filename: ':memory:', // Put the correct driver/config here.
  }),
);
// Don't forget to do this; even here!
PubSub.initPublisher(pubSubConfig, nymph);

const pubsub = createServer(8080, pubSubConfig, nymph);

If you need to provide custom handling in your server (like TLS), you can use the PubSub class directly and provide it a WebSocket server instance.

import http from 'http';
import { server as WebSocketServer } from 'websocket';
import SQLite3Driver from '@nymphjs/driver-sqlite3';
import { Nymph } from '@nymphjs/nymph';
import { PubSub } from '@nymphjs/pubsub';

const pubSubConfig = {
  originIsAllowed: (origin) => {
    // Your logic to determine allowed origins goes here.
    return true;
  },
  entries: ['ws://yourpubsubserver.tld:8080/'],
};

// Set up Nymph.
const nymph = new Nymph(
  {},
  new SQLite3Driver({
    filename: ':memory:', // Put the correct driver/config here.
  }),
);
// Don't forget to do this; even here!
PubSub.initPublisher(pubSubConfig, nymph);

// Set up the PubSub server.
const port = 8080;
const server = http.createServer((_request, response) => {
  response.writeHead(404);
  response.end();
});
const listener = server.listen(port, () => {
  console.log(
    new Date().toISOString(),
    `Nymph-PubSub server started listening on port ${port}.`,
  );
});
const wsServer = new WebSocketServer({
  httpServer: listener,
  // You should not use autoAcceptConnections for production
  // applications, as it defeats all standard cross-origin protection
  // facilities built into the protocol and the browser.  You should
  // *always* verify the connection's origin and decide whether or not
  // to accept it.
  autoAcceptConnections: false,
});

const pubsub = new PubSub(pubSubConfig, nymph, wsServer);

Options

See the config declaration file.

License

Copyright 2021 SciActive Inc

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.