ServerFactory to be used to create server instances for Flipper to use

Summary:
ServerController creates, configures, and contains any necessary servers to be used by Flipper.

ServerFactory is added as a means to abstract the creation of servers from it.

Reviewed By: passy

Differential Revision: D29987328

fbshipit-source-id: ff60a408710dbd51ea28ff27a9f85c0020741f4b

desktop/app/src/comms/ServerFactory.tsx

@@ -0,0 +1,87 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {SecureServerConfig} from '../utils/CertificateProvider';
+import ServerAdapter, {ServerEventsListener} from './ServerAdapter';
+import ServerRSocket from './ServerRSocket';
+import ServerWebSocketBrowser from './ServerWebSocketBrowser';
+
+function _createServer(listener: ServerEventsListener) {
+  /**
+   * GK could be setup or queried to determine whether to use RSocket or
+   * WebSocket. Default is RSocket, but the stage is set for different type
+   * of communication channels.
+   */
+  return new ServerRSocket(listener);
+}
+
+/**
+ * Creates a server to be used by Flipper. The created server will be set into
+ * the promise once it has started and bound to the specified port.
+ * @param port A port number in which to listen for incoming connections.
+ * @param listener An object implementing the ServerEventsListener interface.
+ * @param sslConfig An SSL configuration for TLS servers.
+ */
+export function createServer(
+  port: number,
+  listener: ServerEventsListener,
+  sslConfig?: SecureServerConfig,
+): Promise<ServerAdapter> {
+  return new Promise((resolve, reject) => {
+    const server = _createServer(listener);
+    server
+      .start(port, sslConfig)
+      .then((started) => {
+        if (started) {
+          resolve(server);
+        } else {
+          reject(
+            new Error(`An error occurred whilst trying
+                     to start the server listening at port ${port}`),
+          );
+        }
+      })
+      .catch((error: any) => {
+        reject(error);
+      });
+  });
+}
+
+/**
+ * Creates a server to be used by Flipper to allow Browser connections.
+ * The protocol is slightly different for Browser connections hence a different
+ * factory method. The created server will be set into the promise
+ * once it has started and bound to the specified port.
+ * @param port A port number in which to listen for incoming connections.
+ * @param listener An object implementing the ServerEventsListener interface.
+ * @returns
+ */
+export function createBrowserServer(
+  port: number,
+  listener: ServerEventsListener,
+): Promise<ServerAdapter> {
+  return new Promise((resolve, reject) => {
+    const server = new ServerWebSocketBrowser(listener);
+    server
+      .start(port)
+      .then((started) => {
+        if (started) {
+          resolve(server);
+        } else {
+          reject(
+            new Error(`An error occurred whilst trying
+                     to start the server listening at port ${port}`),
+          );
+        }
+      })
+      .catch((error: any) => {
+        reject(error);
+      });
+  });
+}