Overlook framework start plugin

Part of the Overlook framework.

Usage

Methods

This plugin adds the following methods to a Route:

• [START]
• [START_ROUTE]
• [START_CHILDREN]
• [STOP]
• [STOP_ROUTE]
• [STOP_CHILDREN]

[START] calls [START_ROUTE] and then [START_CHILDREN], which in turn calls [START] on all child routes. So calling [START] on root route will cascade calls to [START_ROUTE] to every route in the routes tree which uses this plugin.

[STOP] works the same, except shutdown occurs in reverse order - children are stopped before parents.

All methods are async (i.e. can return promises).

How to use

If you want to perform some action when the application starts/stops, extend [START_ROUTE] and [STOP_ROUTE] methods.

e.g. To start/stop an express server when application starts/stops:

const Route = require('@overlook/route');
const startPlugin = require('@overlook/plugin-start');
const express = require('express');

const StartStopRoute = Route.extend( startPlugin );
const { START_ROUTE, STOP_ROUTE, START, STOP } = startPlugin;

const SERVER = Symbol('SERVER');
const PORT = 3000;

class ServerRoute extends StartStopRoute {
  async [START_ROUTE]() {
    // Delegate to superiors
    await super[START_ROUTE]();

    // Create express app
    // and wait for server to start
    const expressApp = express();

    expressApp.use( (req, res) => {
      // Overlook uses a single request object
      this.handle( { req, res } );
    } );

    await new Promise( (resolve, reject) => {
      this[SERVER] = expressApp.listen(
        PORT,
        (err) => {
          if ( err ) return reject( err );
          resolve();
        }
      );
    });
  }

  async [STOP_ROUTE]() {
    // Shutdown server
    await new Promise( (resolve, reject) => {
      this[SERVER].close( (err) => {
        if ( err ) return reject( err );
        resolve();
      } );
    } );

    // Delegate to superiors
    // NB After server shutdown so order of
    // stopping is reverse of start up.
    await super[STOP_ROUTE]();
  }
}

const app = new ServerRoute();

// Start app
await app.init();
await app[START]();

// Later, stop app
await app[STOP]();

NB @overlook/plugin-serve-http does much the same as above example.

Versioning

This module follows semver. Breaking changes will only be made in major version updates.

All active NodeJS release lines are supported (v10+ at time of writing). After a release line of NodeJS reaches end of life according to Node's LTS schedule, support for that version of Node may be dropped at any time, and this will not be considered a breaking change. Dropping support for a Node version will be made in a minor version update (e.g. 1.2.0 to 1.3.0). If you are using a Node version which is approaching end of life, pin your dependency of this module to patch updates only using tilde (~) e.g. ~1.2.3 to avoid breakages.

Tests

Use npm test to run the tests. Use npm run cover to check coverage.

Changelog

See changelog.md

Issues

If you discover a bug, please raise an issue on Github. https://github.com/overlookjs/plugin-start/issues

Contribution

Pull requests are very welcome. Please:

• ensure all tests pass before submitting PR
• add tests for new features
• document new functionality/API additions in README
• do not add an entry to Changelog (Changelog is created when cutting releases)