Make transports tree-shakable

We expose WebSocketTransport, XHRPolling, and XHRStreaming modules.

Resolves #1394.

scripts/moduleReport.js

@@ -1,7 +1,15 @@
 const esbuild = require('esbuild');
 
 // List of all modules accepted in ModulesMap
-const moduleNames = ['Rest', 'Crypto', 'MsgPack', 'RealtimePresence'];
+const moduleNames = [
+  'Rest',
+  'Crypto',
+  'MsgPack',
+  'RealtimePresence',
+  'XHRPolling',
+  'XHRStreaming',
+  'WebSocketTransport',
+];
 
 // List of all free-standing functions exported by the library along with the
 // ModulesMap entries that we expect them to transitively import

src/common/lib/client/baserealtime.ts

@@ -11,24 +11,45 @@ import ClientOptions from '../../types/ClientOptions';
 import * as API from '../../../../ably';
 import { ModulesMap } from './modulesmap';
 import RealtimePresence from './realtimepresence';
+import { TransportNames } from 'common/constants/TransportName';
+import { TransportImplementations } from 'common/platform';
 
 /**
  `BaseRealtime` is an export of the tree-shakable version of the SDK, and acts as the base class for the `DefaultRealtime` class exported by the non tree-shakable version.
  */
 class BaseRealtime extends BaseClient {
   readonly _RealtimePresence: typeof RealtimePresence | null;
+  // Extra transport implementations available to this client, in addition to those in Platform.Transports.bundledImplementations
+  readonly _additionalTransportImplementations: TransportImplementations;
   _channels: any;
   connection: Connection;
 
   constructor(options: ClientOptions, modules: ModulesMap) {
     super(options, modules);
     Logger.logAction(Logger.LOG_MINOR, 'Realtime()', '');
+    this._additionalTransportImplementations = BaseRealtime.transportImplementationsFromModules(modules);
     this._RealtimePresence = modules.RealtimePresence ?? null;
     this.connection = new Connection(this, this.options);
     this._channels = new Channels(this);
     if (options.autoConnect !== false) this.connect();
   }
 
+  private static transportImplementationsFromModules(modules: ModulesMap) {
+    const transports: TransportImplementations = {};
+
+    if (modules.WebSocketTransport) {
+      transports[TransportNames.WebSocket] = modules.WebSocketTransport;
+    }
+    if (modules.XHRStreaming) {
+      transports[TransportNames.XhrStreaming] = modules.XHRStreaming;
+    }
+    if (modules.XHRPolling) {
+      transports[TransportNames.XhrPolling] = modules.XHRPolling;
+    }
+
+    return transports;
+  }
+
   get channels() {
     return this._channels;
   }

src/common/lib/client/defaultrealtime.ts

@@ -9,6 +9,7 @@ import { DefaultMessage } from '../types/defaultmessage';
 import { MsgPack } from 'common/types/msgpack';
 import RealtimePresence from './realtimepresence';
 import { DefaultPresenceMessage } from '../types/defaultpresencemessage';
+import initialiseWebSocketTransport from '../transport/websockettransport';
 
 /**
  `DefaultRealtime` is the class that the non tree-shakable version of the SDK exports as `Realtime`. It ensures that this version of the SDK includes all of the functionality which is optionally available in the tree-shakable version.
@@ -20,7 +21,13 @@ export class DefaultRealtime extends BaseRealtime {
       throw new Error('Expected DefaultRealtime._MsgPack to have been set');
     }
 
-    super(options, { ...allCommonModules, Crypto: DefaultRealtime.Crypto ?? undefined, MsgPack, RealtimePresence });
+    super(options, {
+      ...allCommonModules,
+      Crypto: DefaultRealtime.Crypto ?? undefined,
+      MsgPack,
+      RealtimePresence,
+      WebSocketTransport: initialiseWebSocketTransport,
+    });
   }
 
   static Utils = Utils;

src/common/lib/client/modulesmap.ts

@@ -2,12 +2,16 @@ import { Rest } from './rest';
 import { IUntypedCryptoStatic } from '../../types/ICryptoStatic';
 import { MsgPack } from 'common/types/msgpack';
 import RealtimePresence from './realtimepresence';
+import { TransportInitialiser } from '../transport/connectionmanager';
 
 export interface ModulesMap {
   Rest?: typeof Rest;
   Crypto?: IUntypedCryptoStatic;
   MsgPack?: MsgPack;
   RealtimePresence?: typeof RealtimePresence;
+  WebSocketTransport?: TransportInitialiser;
+  XHRPolling?: TransportInitialiser;
+  XHRStreaming?: TransportInitialiser;
 }
 
 export const allCommonModules: ModulesMap = { Rest };

src/common/lib/transport/connectionmanager.ts

@@ -2,7 +2,7 @@ import ProtocolMessage from 'common/lib/types/protocolmessage';
 import * as Utils from 'common/lib/util/utils';
 import Protocol, { PendingMessage } from './protocol';
 import Defaults, { getAgentString } from 'common/lib/util/defaults';
-import Platform from 'common/platform';
+import Platform, { TransportImplementations } from 'common/platform';
 import EventEmitter from '../util/eventemitter';
 import MessageQueue from './messagequeue';
 import Logger from '../util/logger';
@@ -12,14 +12,13 @@ import ErrorInfo, { IPartialErrorInfo, PartialErrorInfo } from 'common/lib/types
 import Auth from 'common/lib/client/auth';
 import Message from 'common/lib/types/message';
 import Multicaster, { MulticasterInstance } from 'common/lib/util/multicaster';
-import WebSocketTransport from './websockettransport';
 import Transport, { TransportCtor } from './transport';
 import * as API from '../../../../ably';
 import { ErrCallback } from 'common/types/utils';
 import HttpStatusCodes from 'common/constants/HttpStatusCodes';
 import BaseRealtime from '../client/baserealtime';
 import { NormalisedClientOptions } from 'common/types/ClientOptions';
-import TransportName from 'common/constants/TransportName';
+import TransportName, { TransportNames } from 'common/constants/TransportName';
 
 let globalObject = typeof global !== 'undefined' ? global : typeof window !== 'undefined' ? window : self;
 
@@ -227,8 +226,8 @@ class ConnectionManager extends EventEmitter {
 
   constructor(realtime: BaseRealtime, options: NormalisedClientOptions) {
     super();
-    this.initTransports();
     this.realtime = realtime;
+    this.initTransports();
     this.options = options;
     const timeouts = options.timeouts;
     /* connectingTimeout: leave preferenceConnectTimeout (~6s) to try the
@@ -401,22 +400,29 @@ class ConnectionManager extends EventEmitter {
    *********************/
 
   // Used by tests
-  static get supportedTransports() {
+  static supportedTransports(additionalImplementations: TransportImplementations) {
     const storage: TransportStorage = { supportedTransports: {} };
-    this.initTransports(storage);
+    this.initTransports(additionalImplementations, storage);
     return storage.supportedTransports;
   }
 
-  private static initTransports(storage: TransportStorage) {
-    WebSocketTransport(storage);
+  private static initTransports(additionalImplementations: TransportImplementations, storage: TransportStorage) {
+    const implementations = { ...Platform.Transports.bundledImplementations, ...additionalImplementations };
+
+    const initialiseWebSocketTransport = implementations[TransportNames.WebSocket];
+    if (initialiseWebSocketTransport) {
+      initialiseWebSocketTransport(storage);
+    }
     Utils.arrForEach(Platform.Transports.order, function (transportName) {
-      const initFn = Platform.Transports.implementations[transportName]!;
-      initFn(ConnectionManager);
+      const initFn = implementations[transportName];
+      if (initFn) {
+        initFn(storage);
+      }
     });
   }
 
   initTransports() {
-    ConnectionManager.initTransports(this);
+    ConnectionManager.initTransports(this.realtime._additionalTransportImplementations, this);
   }
 
   createTransportParams(host: string | null, mode: string): TransportParams {

src/common/platform.ts

@@ -34,7 +34,8 @@ export default class Platform {
   static Http: typeof IHttp;
   static Transports: {
     order: TransportName[];
-    implementations: TransportImplementations;
+    // Transport implementations that always come with this platform
+    bundledImplementations: TransportImplementations;
   };
   static Defaults: IDefaults;
   static WebStorage: IWebStorage | null;

src/platform/nodejs/lib/transport/index.ts

@@ -1,7 +1,11 @@
 import { TransportNames } from 'common/constants/TransportName';
 import initialiseNodeCometTransport from './nodecomettransport';
+import { default as initialiseWebSocketTransport } from '../../../../common/lib/transport/websockettransport';
 
 export default {
   order: [TransportNames.Comet],
-  implementations: { [TransportNames.Comet]: initialiseNodeCometTransport },
+  bundledImplementations: {
+    [TransportNames.WebSocket]: initialiseWebSocketTransport,
+    [TransportNames.Comet]: initialiseNodeCometTransport,
+  },
 };

src/platform/web/lib/transport/index.ts

@@ -1,11 +1,25 @@
-import { TransportNames } from 'common/constants/TransportName';
+import TransportName from 'common/constants/TransportName';
+import Platform from 'common/platform';
 import initialiseXHRPollingTransport from './xhrpollingtransport';
 import initialiseXHRStreamingTransport from './xhrstreamingtransport';
+import { default as initialiseWebSocketTransport } from '../../../../common/lib/transport/websockettransport';
 
-export default {
-  order: [TransportNames.XhrPolling, TransportNames.XhrStreaming],
-  implementations: {
-    [TransportNames.XhrPolling]: initialiseXHRPollingTransport,
-    [TransportNames.XhrStreaming]: initialiseXHRStreamingTransport,
+// For reasons that I don’t understand, if we use [TransportNames.XhrStreaming] and [TransportNames.XhrPolling] for the keys in defaultTransports’s, then defaultTransports does not get tree-shaken. Hence using literals instead. They’re still correctly type-checked.
+
+const order: TransportName[] = ['xhr_polling', 'xhr_streaming'];
+
+const defaultTransports: (typeof Platform)['Transports'] = {
+  order,
+  bundledImplementations: {
+    web_socket: initialiseWebSocketTransport,
+    xhr_polling: initialiseXHRPollingTransport,
+    xhr_streaming: initialiseXHRStreamingTransport,
   },
 };
+
+export default defaultTransports;
+
+export const ModulesTransports: (typeof Platform)['Transports'] = {
+  order,
+  bundledImplementations: {},
+};

src/platform/web/modules.ts

@@ -10,7 +10,7 @@ import BufferUtils from './lib/util/bufferutils';
 import Http from './lib/util/http';
 import Config from './config';
 // @ts-ignore
-import Transports from './lib/transport';
+import { ModulesTransports } from './lib/transport';
 import Logger from '../../common/lib/util/logger';
 import { getDefaults } from '../../common/lib/util/defaults';
 import WebStorage from './lib/util/webstorage';
@@ -19,7 +19,7 @@ import PlatformDefaults from './lib/util/defaults';
 Platform.BufferUtils = BufferUtils;
 Platform.Http = Http;
 Platform.Config = Config;
-Platform.Transports = Transports;
+Platform.Transports = ModulesTransports;
 Platform.WebStorage = WebStorage;
 
 Logger.initLogHandlers();
@@ -44,5 +44,6 @@ export * from './modules/message';
 export * from './modules/presencemessage';
 export * from './modules/msgpack';
 export * from './modules/realtimepresence';
+export * from './modules/transports';
 export { Rest } from '../../common/lib/client/rest';
 export { BaseRest, BaseRealtime, ErrorInfo };

src/platform/web/modules/transports.ts

@@ -0,0 +1,3 @@
+export { default as XHRPolling } from '../lib/transport/xhrpollingtransport';
+export { default as XHRStreaming } from '../lib/transport/xhrstreamingtransport';
+export { default as WebSocketTransport } from '../../../common/lib/transport/websockettransport';