graasp-plugin-websockets

A websockets extension for Graasp exposed through a fastify plugin

This project provides back-end support for WebSockets in the Graasp ecosystem. It implements a Fastify plugin that can be registered into the core Graasp Fastify server instance.

This plugin provides real-time communication across Graasp server clusters and all connected clients through a channel broadcast abstraction implemented on top of WebSocket. It provides real-time events sent to clients following a publish / subscribe pattern.

Usage

This plugin requires a Redis instance which serves as a relay when multiple instances of Graasp run as a cluster (for instance for load balancing purposes).

Add this plugin repository to the dependencies section of the package.json of your Graasp server instance:

yarn add @graasp/sdk @graasp/plugin-websockets

In the file of the designated WebSocket endpoint route, import the plugin:

import graaspWebSockets from '@graasp/plugin-websockets';

Register the plugin on your Fastify instance (here instance is the core Graasp Fastify instance, initialized / obtained beforehand):

    // make sure to register dependent services before!
    await instance.register(authPlugin, ...)
    await instance.register(itemService, ...)
    await instance.register(itemMembershipService, ...)
    //...
    // then register graasp-plugin-websockets as follows
    await instance.register(graaspWebSockets);

Services that are destructured from the Fastify instance in src/service-api.ts must be registered beforehand and decorate it with the corresponding names, as defined in @graasp/sdk (i.e. validateSession, log, items = { taskManager }, ...)!

The plugin accepts the following options (which all have sane defaults):

    await instance.register(graaspWebSockets, {
        prefix: '/ws',
        redis: {
            config: {
                host: REDIS_HOST,
                port: +REDIS_PORT,
                username: REDIS_USERNAME,
                password: REDIS_PASSWORD,
                ... // any other RedisOptions property from 'ioredis'
            }
            channelName: 'graasp-notif',
        }
    });

where:

• prefix is the route of the websocket endpoint, relative to current registration scope. Websocket clients connect to this route to upgrade from HTTP(S) to WS(S).
• redis.config is the configuration required to connect to the Redis server instance, which can contain any property from the RedisOptions type from ioredis (see API reference).
• redis.channelName is the name of the Redis pub/sub channel used to share websocket messages across multiple server instance (for instance in a cluster).

The plugin will also decorate the Fastify instance with a websocket service under the websockets property. Read USAGE.md for instructions on how to consume this service from other parts of the server, such as other plugins.

Adding behaviour with websockets

If you want to use real-time updates from the server in front-end Graasp applications (e.g. graasp-compose) that require real-time feedback or add additional real-time behaviour that is not implemented yet, make sure to follow this guide: USAGE.md

API

This plugin implements a custom protocol over WebSoket between clients and this server plugin to send real-time notifications for specific Graasp behaviours. Please read API.md for more information about the messages format used between the server and clients that subscribe to updates from graasp-plugin-websockets.

Building locally

If you'd like to run the code for other purposes (such as reusing modules without Graasp or just trying things out locally), clone this repository with:

git clone https://github.com/graasp/graasp-plugin-websockets.git

Then navigate into the cloned folder:

cd graasp-plugin-websockets

Install the dependencies:

yarn install

Compile the code:

yarn build

Files are compiled into the dist/ folder.

You can then run tests as described below, or import parts of the implementation into your own files.

Cleaning artifacts

You can clean compiled and generated files from the repository folder using:

yarn clean

Testing

Several test suites are provided in folder test/. They include unit tests as well as end-to-end tests written for the Jest testing framework using the ts-jest transformer to run TypeScript tests directly. The configuration is specified by jest.config.js.

To run the tests, make sure that you have installed the dependencies at least once:

yarn install

Then simply use the test script (defined in package.json):

yarn test

You will obtain the Jest summary in the console.

Code coverage

Jest will also provide code coverage results directly in the console. It also generates a detailed line coverage report in the coverage/ folder.

You can inspect it by first running the tests and then opening the following file in your web browser (substitute firefox with your browser of choice, or simply find the file in your file manager and open it):

firefox coverage/lcov-report/index.html

You can then browse folders, files and lines of code with coverage annotations directly in your web browser.

Lint issues

Code quality is enforced using ESLint and its configuration is specified in .eslintrc.js and .eslintignore.

To see a list of lint issues found in the code, run:

yarn lint

Continuous integration

This repository also includes a run configuration for Github Actions in .github/workflows/main.yml. package.json provides the test:ci script to be used for testing in continuous integration environments.

Troubleshooting

If your project depends on graasp-plugin-websockets, cannot fetch the graasp-plugin-websockets repository in your continuous integration system (such as Github Actions) and uses yarn ci as the install command, try using yarn install instead. There are known issues with Github SSH keys management.

Repository structure

• .github/: Github-related configurations, such as Actions
• src/: source code of the graasp-plugin-websockets plugin and its modules
• test/: Jest unit and end-to-end tests (file names match sources in src/)
• README.md: this file
• tsconfig.json: TypeScript compiler configuration

Author

This project was originally written for a 2021 Master Semester project at the REACT group at EPFL:

• Alexandre CHAU (alexandre.chau@alumni.epfl.ch)
• Coordination & Interaction Systems Group (REACT)
• Ecole Polytechnique Fédérale de Lausanne (EPFL)

Acknowledgements:

• André NOGUEIRA
• Kim PHAN
• Denis GILLET
• Nicolas MACRIS

License

This project and repository are licensed under the GNU Affero General Public License Version 3. Please read the LICENSE file for more details.

    graasp-plugin-websockets - WebSockets for Graasp
    Copyright (C) 2021 EPFL REACT

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published
    by the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.