nmos-ledger/model/Node.js

NMOS discovery and registration APIs

/* Copyright 2016 Streampunk Media Ltd.

  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.
*/

// Describes the Node and the services which run on it

var Versionned = require('./Versionned.js');
var immutable = require('seamless-immutable');
var Capabilities = require('./Capabilities.js');

/**
 * Describes a Node. Immutable value.
 * @constructor
 * @augments Versionned
 * @param {string} id       Globally unique UUID identifier for the Node.
 * @param {string} version  String formatted PTP timestamp
 *                          (&lt;<em>seconds</em>&gt;:&lt;<em>nanoseconds</em>&gt;)
 *                          indicating precisely when an attribute of the resource
 *                          last changed.
 * @param {string} label    Freeform string label for the Node.
 * @param {string} href     HTTP access href for the Node's API.
 * @param {string} hostname Node hostname - set to null when not present.
 * @param {Object} caps     [Capabilities]{@link capabilities} (not yet defined).
 * @param {Object[]} services Array of objects containing a URN format type and href.
 */
function Node(id, version, label, href, hostname, caps, services) {
  this.id = this.generateID(id);
  this.version = this.generateVersion(version);
  this.label = this.generateLabel(label);
  /**
   * HTTP access href for the Node's API.
   * @type {string}
   * @readonly
  */
  this.href = this.generateHref(href);
  /**
   * Node hostname - set to null when not present.
   * @type {string}
   * @readonly
   */
  this.hostname = this.generateHostname(hostname);
  /**
   * [Capabilities]{@link capabilities} (not yet defined).
   * @type {Object}
   * @readonly
   */
  this.caps = this.generateCaps(caps);
  /**
   * Array of objects containing a URN format type and href.
   * @type {Object[]}
   * @readonly
   */
  this.services = this.generateServices(services);
  return immutable(this, { prototype : Node.prototype });
}

Node.prototype.validID = Versionned.prototype.validID;
Node.prototype.generateID = Versionned.prototype.generateID;
Node.prototype.validVersion = Versionned.prototype.validVersion;
Node.prototype.generateVersion = Versionned.prototype.generateVersion;
Node.prototype.validLabel = Versionned.prototype.validLabel;
Node.prototype.generateLabel = Versionned.prototype.generateLabel;

Node.prototype.validHref = function (href) {
  if (arguments.length === 0) return this.validHref(this.href);
  return typeof href === 'string' &&
    href.startsWith('http://');
}

Node.prototype.generateHref = function (href) {
  if (arguments.length === 0 || href === null || href === undefined)
    return 'http://localhost/';
  else return href;
}

// Consider a test to check that hostnames doesn't contain spaces
Node.prototype.validHostname = function (hostname) {
  if (arguments.length === 0) return this.validHostname(this.hostname);
  if (hostname === undefined) return true;
  return typeof hostname === 'string' &&
    hostname.match(/^[^\s]+$/) !== null;
}

Node.prototype.generateHostname = function (hostname) {
  if (arguments.length === 0 || hostname === null || hostname === undefined)
    return undefined;
  else return hostname;
}

Node.prototype.validCaps = Versionned.prototype.validCaps;
Node.prototype.generateCaps = Versionned.prototype.generateCaps;

Node.prototype.validServices = function (services) {
  if (arguments.length === 0) return this.validServices(this.services);
  return Array.isArray(services) &&
    services.every(function (s) {
      return typeof s === 'object' &&
        !Array.isArray(s) &&
        s.hasOwnProperty('href') &&
        s.hasOwnProperty('type') &&
        typeof s.href === 'string' &&
        typeof s.type === 'string' &&
        s.href.startsWith('http://');
    });
}
Node.prototype.generateServices = function (services) {
  if (arguments.length === 0 || services === null || services === undefined)
    return [];
  else return services;
}

Node.prototype.valid = function () {
  return this.validID(this.id) &&
    this.validVersion(this.version) &&
    this.validLabel(this.label) &&
    this.validHref(this.href) &&
    this.validHostname(this.hostName) &&
    this.validCaps(this.caps) &&
    this.validServices(this.services);
}

Node.prototype.stringify = function() { return JSON.stringify(this); }

Node.prototype.parse = function (json) {
  if (json === null || json === undefined || arguments.length === 0 ||
      (typeof json !== 'string' && typeof json !== 'object'))
    throw "Cannot parse JSON to a Node value because it is not a valid input.";
  var parsed = typeof json === 'string' ? JSON.parse(json) : json;
  return new Node(parsed.id, parsed.version, parsed.label, parsed.href,
    parsed.hostname, parsed.caps, parsed.services);
}

Node.isNode = function (x) {
  return x !== null &&
    typeof x === 'object' &&
    x.constructor === Node.prototype.constructor;
}

module.exports = Node;