Make connecting the WebSocket optional

In preparation for splitting the hosting of the WebSocket server into a
separate process, make it possible to run the client without attempting
to connect to the WebSocket.

If the `websocketUrl` setting is missing, we will not attempt to
connect.

h/static/scripts/streamer.js

@@ -26,15 +26,24 @@ var socket;
  */
 // @ngInject
 function connect($rootScope, annotationMapper, groups, session, settings) {
-  // Get the socket URL
-  var url = settings.websocketUrl;
+  // The public interface of the streamer. Returned from connect.
+  var controls = {
+    setConfig: setConfig
+  };
+  // Client configuration messages, to be sent each time a new connection is
+  // established.
+  var configMessages = {};
 
   // Close any existing socket
   if (socket) {
     socket.close();
   }
 
-  var configMessages = {};
+  // If we have no URL configured, don't do anything.
+  var url = settings.websocketUrl;
+  if (!url) {
+    return controls;
+  }
 
   // Open the socket
   socket = new Socket(url);
@@ -82,6 +91,18 @@ function connect($rootScope, annotationMapper, groups, session, settings) {
     });
   }
 
+  /**
+   * Send a configuration message to the push notification service.
+   * Each message is associated with a key, which is used to re-send
+   * configuration data to the server in the event of a reconnection.
+   */
+  function setConfig(key, configMessage) {
+    configMessages[key] = configMessage;
+    if (socket && socket.isConnected()) {
+      socket.send(configMessage);
+    }
+  }
+
   socket.on('open', function () {
     sendClientConfig();
   });
@@ -110,21 +131,7 @@ function connect($rootScope, annotationMapper, groups, session, settings) {
     });
   });
 
-  /**
-   * Send a configuration message to the push notification service.
-   * Each message is associated with a key, which is used to re-send
-   * configuration data to the server in the event of a reconnection.
-   */
-  function setConfig(key, configMessage) {
-    configMessages[key] = configMessage;
-    if (socket.isConnected()) {
-      socket.send(configMessage);
-    }
-  }
-
-  return {
-    setConfig: setConfig,
-  };
+  return controls;
 }
 
 module.exports = {

h/static/scripts/test/streamer-test.js

@@ -6,7 +6,7 @@ var EventEmitter = require('tiny-emitter');
 var proxyquire = require('proxyquire');
 
 // the most recently created FakeSocket instance
-var fakeWebSocket;
+var fakeWebSocket = null;
 
 function FakeSocket(url) {
   fakeWebSocket = this;
@@ -37,6 +37,16 @@ describe('streamer', function () {
   var fakeSettings;
   var activeStreamer;
 
+  function createDefaultStreamer() {
+    activeStreamer = streamer.connect(
+      fakeRootScope,
+      fakeAnnotationMapper,
+      fakeGroups,
+      fakeSession,
+      fakeSettings
+    );
+  }
+
   beforeEach(function () {
     fakeRootScope = {
       $apply: function (callback) {
@@ -66,23 +76,23 @@ describe('streamer', function () {
     streamer = proxyquire('../streamer', {
       './websocket': FakeSocket,
     });
+  });
 
-    activeStreamer = streamer.connect(
-      fakeRootScope,
-      fakeAnnotationMapper,
-      fakeGroups,
-      fakeSession,
-      fakeSettings
-    );
+  it('should not create a websocket connection if websocketUrl is not provided', function () {
+    fakeSettings = {}
+    createDefaultStreamer();
+    assert.isNull(fakeWebSocket);
   });
 
   it('should send a client ID', function () {
+    createDefaultStreamer();
     assert.equal(fakeWebSocket.messages.length, 1);
     assert.equal(fakeWebSocket.messages[0].messageType, 'client_id');
     assert.equal(fakeWebSocket.messages[0].value, streamer.clientId);
   });
 
   it('should close any existing socket', function () {
+    createDefaultStreamer();
     var oldStreamer = activeStreamer;
     var oldWebSocket = fakeWebSocket;
     var newStreamer = streamer.connect(
@@ -98,6 +108,7 @@ describe('streamer', function () {
 
   describe('annotation notifications', function () {
     it('should load new annotations', function () {
+      createDefaultStreamer();
       fakeWebSocket.notify({
         type: 'annotation-notification',
         options: {
@@ -111,6 +122,7 @@ describe('streamer', function () {
     });
 
     it('should unload deleted annotations', function () {
+      createDefaultStreamer();
       fakeWebSocket.notify({
         type: 'annotation-notification',
         options: {
@@ -126,6 +138,7 @@ describe('streamer', function () {
 
   describe('session change notifications', function () {
     it('updates the session when a notification is received', function () {
+      createDefaultStreamer();
       var model = {
         groups: [{
           id: 'new-group'
@@ -141,6 +154,7 @@ describe('streamer', function () {
 
   describe('reconnections', function () {
     it('resends configuration messages when a reconnection occurs', function () {
+      createDefaultStreamer();
       fakeWebSocket.messages = [];
       fakeWebSocket.emit('open');
       assert.equal(fakeWebSocket.messages.length, 1);