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Chat with Java and Servlets

(warning)

Warning

As the Programmable Chat API is set to sunset in 2022, we will no longer maintain these chat tutorials.

Please see our Conversations API QuickStart to start building robust virtual spaces for conversation.

(error)

Danger

Programmable Chat has been deprecated and is no longer supported. Instead, we'll be focusing on the next generation of chat: Twilio Conversations. Find out more about the EOL process here.

If you're starting a new project, please visit the Conversations Docs to begin. If you've already built on Programmable Chat, please visit our Migration Guide to learn about how to switch.

Ready to implement a chat application using Twilio Programmable Chat Client?

This application allows users to exchange messages through different channels, using the Twilio Programmable Chat API. In this example, we'll show how to use this API capabilities to manage channels and their usages.

Properati built a web and mobile messaging app to help real estate buyers and sellers connect in real time. Learn more here.

For your convenience, we consolidated the source code for this tutorial in a single GitHub repository. Feel free to clone it and tweak it as required.

Generate the Token

In order to create a Twilio Programmable Chat client, you will need an access token. This token holds information about your Twilio Account and Chat API keys.

We generate this token by creating a new AccessToken and providing it with a ChatGrant. With the AccessToken at hand, we can use its method ToJWT() to return its string representation.

Generate an Access Token

src/main/java/com/twilio/chat/TwilioTokenCreator.java


_32package com.twilio.chat;
_32
_32import javax.inject.Inject;
_32
_32import com.twilio.jwt.accesstoken.AccessToken;
_32import com.twilio.jwt.accesstoken.ChatGrant;
_32
_32public class TwilioTokenCreator {
_32
_32  private final AppConfig appConfig;
_32
_32  @Inject
_32  public TwilioTokenCreator(AppConfig appConfig) {
_32    this.appConfig = appConfig;
_32    if (appConfig.isIncomplete()) {
_32      throw new IncompleteConfigException(appConfig);
_32    }
_32  }
_32
_32  String generateToken(String identity) {
_32    ChatGrant grant = new ChatGrant();
_32    grant.setServiceSid(appConfig.getTwilioChatServiceSID());
_32
_32    AccessToken token = new AccessToken.Builder(
_32      appConfig.getTwilioAccountSID(),
_32      appConfig.getTwilioAPIKey(),
_32      appConfig.getTwilioAPISecret()
_32    ).identity(identity).grant(grant).build();
_32
_32    return token.toJwt();
_32  }
_32}

We can generate a token, now we need a way for the chat app to get it.

Token Generation Controller

On our controller we expose the endpoint responsible for providing a valid token. Using this parameter:

identity : identifies the user itself.

It uses tokenGenerator.Generate method to get hold of a new token and return it in a JSON format to be used for our client.

Token Generation Controller

src/main/java/com/twilio/chat/TokenServlet.java


_52package com.twilio.chat;
_52
_52import java.io.BufferedWriter;
_52import java.io.IOException;
_52import java.util.HashMap;
_52import java.util.Map;
_52
_52import javax.inject.Inject;
_52import javax.servlet.http.HttpServlet;
_52import javax.servlet.http.HttpServletRequest;
_52import javax.servlet.http.HttpServletResponse;
_52
_52import com.google.gson.Gson;
_52import com.google.inject.Singleton;
_52
_52@Singleton
_52public class TokenServlet extends HttpServlet {
_52
_52  private final TwilioTokenCreator tokenCreator;
_52
_52  @Inject
_52  public TokenServlet(TwilioTokenCreator tokenCreator) {
_52    this.tokenCreator = tokenCreator;
_52  }
_52
_52  @Override
_52  public void doPost(HttpServletRequest request, HttpServletResponse response) {
_52    String identity = request.getParameter("identity");
_52
_52    if (identity != null) {
_52
_52      String generatedToken = tokenCreator.generateToken(identity);
_52
_52      Map<String, String> json = new HashMap<>();
_52      json.put("identity", identity);
_52      json.put("token", generatedToken);
_52      renderJson(response, json);
_52    }
_52
_52  }
_52
_52  private void renderJson(HttpServletResponse response, Map<String, String> json) {
_52    Gson gson = new Gson();
_52    response.setContentType("application/json");
_52    try (BufferedWriter responseWriter = new BufferedWriter(response.getWriter())) {
_52      responseWriter.write(gson.toJson(json));
_52      responseWriter.flush();
_52    } catch (IOException e) {
_52      e.printStackTrace();
_52    }
_52  }
_52}

Now that we have a route that generates JWT tokens on demand, let's use this route to initialize our Twilio Chat Client.

Initialize the Programmable Chat Client

On our client, we fetch a new Token using a POST request to our endpoint.

With the token, we can create a new Twilio.AccessManager, and initialize our Twilio.Chat.Client.

Initialize the Chat Client

src/main/webapp/js/twiliochat.js


_363var twiliochat = (function() {
_363  var tc = {};
_363
_363  var GENERAL_CHANNEL_UNIQUE_NAME = 'general';
_363  var GENERAL_CHANNEL_NAME = 'General Channel';
_363  var MESSAGES_HISTORY_LIMIT = 50;
_363
_363  var $channelList;
_363  var $inputText;
_363  var $usernameInput;
_363  var $statusRow;
_363  var $connectPanel;
_363  var $newChannelInputRow;
_363  var $newChannelInput;
_363  var $typingRow;
_363  var $typingPlaceholder;
_363
_363  $(document).ready(function() {
_363    tc.$messageList = $('#message-list');
_363    $channelList = $('#channel-list');
_363    $inputText = $('#input-text');
_363    $usernameInput = $('#username-input');
_363    $statusRow = $('#status-row');
_363    $connectPanel = $('#connect-panel');
_363    $newChannelInputRow = $('#new-channel-input-row');
_363    $newChannelInput = $('#new-channel-input');
_363    $typingRow = $('#typing-row');
_363    $typingPlaceholder = $('#typing-placeholder');
_363    $usernameInput.focus();
_363    $usernameInput.on('keypress', handleUsernameInputKeypress);
_363    $inputText.on('keypress', handleInputTextKeypress);
_363    $newChannelInput.on('keypress', tc.handleNewChannelInputKeypress);
_363    $('#connect-image').on('click', connectClientWithUsername);
_363    $('#add-channel-image').on('click', showAddChannelInput);
_363    $('#leave-span').on('click', disconnectClient);
_363    $('#delete-channel-span').on('click', deleteCurrentChannel);
_363  });
_363
_363  function handleUsernameInputKeypress(event) {
_363    if (event.keyCode === 13){
_363      connectClientWithUsername();
_363    }
_363  }
_363
_363  function handleInputTextKeypress(event) {
_363    if (event.keyCode === 13) {
_363      tc.currentChannel.sendMessage($(this).val());
_363      event.preventDefault();
_363      $(this).val('');
_363    }
_363    else {
_363      notifyTyping();
_363    }
_363  }
_363
_363  var notifyTyping = $.throttle(function() {
_363    tc.currentChannel.typing();
_363  }, 1000);
_363
_363  tc.handleNewChannelInputKeypress = function(event) {
_363    if (event.keyCode === 13) {
_363      tc.messagingClient.createChannel({
_363        friendlyName: $newChannelInput.val()
_363      }).then(hideAddChannelInput);
_363      $(this).val('');
_363      event.preventDefault();
_363    }
_363  };
_363
_363  function connectClientWithUsername() {
_363    var usernameText = $usernameInput.val();
_363    $usernameInput.val('');
_363    if (usernameText == '') {
_363      alert('Username cannot be empty');
_363      return;
_363    }
_363    tc.username = usernameText;
_363    fetchAccessToken(tc.username, connectMessagingClient);
_363  }
_363
_363  function fetchAccessToken(username, handler) {
_363    $.post('/twiliochat-servlets/token', {identity: username}, null, 'json')
_363      .done(function(response) {
_363        console.log('Successfully finished fetch of the Access Token.');
_363        handler(response.token);
_363      })
_363      .fail(function(error) {
_363        console.log('Failed to fetch the Access Token with error: ' + error);
_363      });
_363  }
_363
_363  function connectMessagingClient(token) {
_363    // Initialize the Chat messaging client
_363    tc.accessManager = new Twilio.AccessManager(token);
_363    Twilio.Chat.Client.create(token).then(function(client) {
_363      tc.messagingClient = client;
_363      updateConnectedUI();
_363      tc.loadChannelList(tc.joinGeneralChannel);
_363      tc.messagingClient.on('channelAdded', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('channelRemoved', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('tokenExpired', refreshToken);
_363    });
_363  }
_363
_363  function refreshToken() {
_363    fetchAccessToken(tc.username, setNewToken);
_363  }
_363
_363  function setNewToken(tokenResponse) {
_363    tc.accessManager.updateToken(tokenResponse.token);
_363  }
_363
_363  function updateConnectedUI() {
_363    $('#username-span').text(tc.username);
_363    $statusRow.addClass('connected').removeClass('disconnected');
_363    tc.$messageList.addClass('connected').removeClass('disconnected');
_363    $connectPanel.addClass('connected').removeClass('disconnected');
_363    $inputText.addClass('with-shadow');
_363    $typingRow.addClass('connected').removeClass('disconnected');
_363  }
_363
_363  tc.loadChannelList = function(handler) {
_363    if (tc.messagingClient === undefined) {
_363      console.log('Client is not initialized');
_363      return;
_363    }
_363
_363    tc.messagingClient.getPublicChannelDescriptors().then(function(channels) {
_363      tc.channelArray = tc.sortChannelsByName(channels.items);
_363      $channelList.text('');
_363      tc.channelArray.forEach(addChannel);
_363      if (typeof handler === 'function') {
_363        handler();
_363      }
_363    });
_363  };
_363
_363  tc.joinGeneralChannel = function() {
_363    console.log('Attempting to join "general" chat channel...');
_363    if (!tc.generalChannel) {
_363      // If it doesn't exist, let's create it
_363      tc.messagingClient.createChannel({
_363        uniqueName: GENERAL_CHANNEL_UNIQUE_NAME,
_363        friendlyName: GENERAL_CHANNEL_NAME
_363      }).then(function(channel) {
_363        console.log('Created general channel');
_363        tc.generalChannel = channel;
_363        tc.loadChannelList(tc.joinGeneralChannel);
_363      });
_363    }
_363    else {
_363      console.log('Found general channel:');
_363      setupChannel(tc.generalChannel);
_363    }
_363  };
_363
_363  function initChannel(channel) {
_363    console.log('Initialized channel ' + channel.friendlyName);
_363    return tc.messagingClient.getChannelBySid(channel.sid);
_363  }
_363
_363  function joinChannel(_channel) {
_363    return _channel.join()
_363      .then(function(joinedChannel) {
_363        console.log('Joined channel ' + joinedChannel.friendlyName);
_363        updateChannelUI(_channel);
_363        tc.currentChannel = _channel;
_363        tc.loadMessages();
_363        return joinedChannel;
_363      });
_363  }
_363
_363  function initChannelEvents() {
_363    console.log(tc.currentChannel.friendlyName + ' ready.');
_363    tc.currentChannel.on('messageAdded', tc.addMessageToList);
_363    tc.currentChannel.on('typingStarted', showTypingStarted);
_363    tc.currentChannel.on('typingEnded', hideTypingStarted);
_363    tc.currentChannel.on('memberJoined', notifyMemberJoined);
_363    tc.currentChannel.on('memberLeft', notifyMemberLeft);
_363    $inputText.prop('disabled', false).focus();
_363  }
_363
_363  function setupChannel(channel) {
_363    return leaveCurrentChannel()
_363      .then(function() {
_363        return initChannel(channel);
_363      })
_363      .then(function(_channel) {
_363        return joinChannel(_channel);
_363      })
_363      .then(initChannelEvents);
_363  }
_363
_363  tc.loadMessages = function() {
_363    tc.currentChannel.getMessages(MESSAGES_HISTORY_LIMIT)
_363      .then(function(messages) {
_363        messages.items.forEach(tc.addMessageToList);
_363    });
_363  };
_363
_363  function leaveCurrentChannel() {
_363    if (tc.currentChannel) {
_363      return tc.currentChannel.leave().then(function(leftChannel) {
_363        console.log('left ' + leftChannel.friendlyName);
_363        leftChannel.removeListener('messageAdded', tc.addMessageToList);
_363        leftChannel.removeListener('typingStarted', showTypingStarted);
_363        leftChannel.removeListener('typingEnded', hideTypingStarted);
_363        leftChannel.removeListener('memberJoined', notifyMemberJoined);
_363        leftChannel.removeListener('memberLeft', notifyMemberLeft);
_363      });
_363    } else {
_363      return Promise.resolve();
_363    }
_363  }
_363
_363  tc.addMessageToList = function(message) {
_363    var rowDiv = $('<div>').addClass('row no-margin');
_363    rowDiv.loadTemplate($('#message-template'), {
_363      username: message.author,
_363      date: dateFormatter.getTodayDate(message.dateCreated),
_363      body: message.body
_363    });
_363    if (message.author === tc.username) {
_363      rowDiv.addClass('own-message');
_363    }
_363
_363    tc.$messageList.append(rowDiv);
_363    scrollToMessageListBottom();
_363  };
_363
_363  function notifyMemberJoined(member) {
_363    notify(member.identity + ' joined the channel')
_363  }
_363
_363  function notifyMemberLeft(member) {
_363    notify(member.identity + ' left the channel');
_363  }
_363
_363  function notify(message) {
_363    var row = $('<div>').addClass('col-md-12');
_363    row.loadTemplate('#member-notification-template', {
_363      status: message
_363    });
_363    tc.$messageList.append(row);
_363    scrollToMessageListBottom();
_363  }
_363
_363  function showTypingStarted(member) {
_363    $typingPlaceholder.text(member.identity + ' is typing...');
_363  }
_363
_363  function hideTypingStarted(member) {
_363    $typingPlaceholder.text('');
_363  }
_363
_363  function scrollToMessageListBottom() {
_363    tc.$messageList.scrollTop(tc.$messageList[0].scrollHeight);
_363  }
_363
_363  function updateChannelUI(selectedChannel) {
_363    var channelElements = $('.channel-element').toArray();
_363    var channelElement = channelElements.filter(function(element) {
_363      return $(element).data().sid === selectedChannel.sid;
_363    });
_363    channelElement = $(channelElement);
_363    if (tc.currentChannelContainer === undefined && selectedChannel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.currentChannelContainer = channelElement;
_363    }
_363    tc.currentChannelContainer.removeClass('selected-channel').addClass('unselected-channel');
_363    channelElement.removeClass('unselected-channel').addClass('selected-channel');
_363    tc.currentChannelContainer = channelElement;
_363  }
_363
_363  function showAddChannelInput() {
_363    if (tc.messagingClient) {
_363      $newChannelInputRow.addClass('showing').removeClass('not-showing');
_363      $channelList.addClass('showing').removeClass('not-showing');
_363      $newChannelInput.focus();
_363    }
_363  }
_363
_363  function hideAddChannelInput() {
_363    $newChannelInputRow.addClass('not-showing').removeClass('showing');
_363    $channelList.addClass('not-showing').removeClass('showing');
_363    $newChannelInput.val('');
_363  }
_363
_363  function addChannel(channel) {
_363    if (channel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.generalChannel = channel;
_363    }
_363    var rowDiv = $('<div>').addClass('row channel-row');
_363    rowDiv.loadTemplate('#channel-template', {
_363      channelName: channel.friendlyName
_363    });
_363
_363    var channelP = rowDiv.children().children().first();
_363
_363    rowDiv.on('click', selectChannel);
_363    channelP.data('sid', channel.sid);
_363    if (tc.currentChannel && channel.sid === tc.currentChannel.sid) {
_363      tc.currentChannelContainer = channelP;
_363      channelP.addClass('selected-channel');
_363    }
_363    else {
_363      channelP.addClass('unselected-channel')
_363    }
_363
_363    $channelList.append(rowDiv);
_363  }
_363
_363  function deleteCurrentChannel() {
_363    if (!tc.currentChannel) {
_363      return;
_363    }
_363    if (tc.currentChannel.sid === tc.generalChannel.sid) {
_363      alert('You cannot delete the general channel');
_363      return;
_363    }
_363    tc.currentChannel.delete().then(function(channel) {
_363      console.log('channel: '+ channel.friendlyName + ' deleted');
_363      setupChannel(tc.generalChannel);
_363    });
_363  }
_363
_363  function selectChannel(event) {
_363    var target = $(event.target);
_363    var channelSid = target.data().sid;
_363    var selectedChannel = tc.channelArray.filter(function(channel) {
_363      return channel.sid === channelSid;
_363    })[0];
_363    if (selectedChannel === tc.currentChannel) {
_363      return;
_363    }
_363    setupChannel(selectedChannel);
_363  };
_363
_363  function disconnectClient() {
_363    leaveCurrentChannel();
_363    $channelList.text('');
_363    tc.$messageList.text('');
_363    channels = undefined;
_363    $statusRow.addClass('disconnected').removeClass('connected');
_363    tc.$messageList.addClass('disconnected').removeClass('connected');
_363    $connectPanel.addClass('disconnected').removeClass('connected');
_363    $inputText.removeClass('with-shadow');
_363    $typingRow.addClass('disconnected').removeClass('connected');
_363  }
_363
_363  tc.sortChannelsByName = function(channels) {
_363    return channels.sort(function(a, b) {
_363      if (a.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return -1;
_363      }
_363      if (b.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return 1;
_363      }
_363      return a.friendlyName.localeCompare(b.friendlyName);
_363    });
_363  };
_363
_363  return tc;
_363})();

Now that we've initialized our Chat Client, let's see how we can get a list of channels.

Get the Channel List

After initializing the client, we can call its method getPublicChannelDescriptors to retrieve all visible channels. The method returns a promise which we use to show the list of channels retrieved on the UI.

Get the Channel List

src/main/webapp/js/twiliochat.js


_363var twiliochat = (function() {
_363  var tc = {};
_363
_363  var GENERAL_CHANNEL_UNIQUE_NAME = 'general';
_363  var GENERAL_CHANNEL_NAME = 'General Channel';
_363  var MESSAGES_HISTORY_LIMIT = 50;
_363
_363  var $channelList;
_363  var $inputText;
_363  var $usernameInput;
_363  var $statusRow;
_363  var $connectPanel;
_363  var $newChannelInputRow;
_363  var $newChannelInput;
_363  var $typingRow;
_363  var $typingPlaceholder;
_363
_363  $(document).ready(function() {
_363    tc.$messageList = $('#message-list');
_363    $channelList = $('#channel-list');
_363    $inputText = $('#input-text');
_363    $usernameInput = $('#username-input');
_363    $statusRow = $('#status-row');
_363    $connectPanel = $('#connect-panel');
_363    $newChannelInputRow = $('#new-channel-input-row');
_363    $newChannelInput = $('#new-channel-input');
_363    $typingRow = $('#typing-row');
_363    $typingPlaceholder = $('#typing-placeholder');
_363    $usernameInput.focus();
_363    $usernameInput.on('keypress', handleUsernameInputKeypress);
_363    $inputText.on('keypress', handleInputTextKeypress);
_363    $newChannelInput.on('keypress', tc.handleNewChannelInputKeypress);
_363    $('#connect-image').on('click', connectClientWithUsername);
_363    $('#add-channel-image').on('click', showAddChannelInput);
_363    $('#leave-span').on('click', disconnectClient);
_363    $('#delete-channel-span').on('click', deleteCurrentChannel);
_363  });
_363
_363  function handleUsernameInputKeypress(event) {
_363    if (event.keyCode === 13){
_363      connectClientWithUsername();
_363    }
_363  }
_363
_363  function handleInputTextKeypress(event) {
_363    if (event.keyCode === 13) {
_363      tc.currentChannel.sendMessage($(this).val());
_363      event.preventDefault();
_363      $(this).val('');
_363    }
_363    else {
_363      notifyTyping();
_363    }
_363  }
_363
_363  var notifyTyping = $.throttle(function() {
_363    tc.currentChannel.typing();
_363  }, 1000);
_363
_363  tc.handleNewChannelInputKeypress = function(event) {
_363    if (event.keyCode === 13) {
_363      tc.messagingClient.createChannel({
_363        friendlyName: $newChannelInput.val()
_363      }).then(hideAddChannelInput);
_363      $(this).val('');
_363      event.preventDefault();
_363    }
_363  };
_363
_363  function connectClientWithUsername() {
_363    var usernameText = $usernameInput.val();
_363    $usernameInput.val('');
_363    if (usernameText == '') {
_363      alert('Username cannot be empty');
_363      return;
_363    }
_363    tc.username = usernameText;
_363    fetchAccessToken(tc.username, connectMessagingClient);
_363  }
_363
_363  function fetchAccessToken(username, handler) {
_363    $.post('/twiliochat-servlets/token', {identity: username}, null, 'json')
_363      .done(function(response) {
_363        console.log('Successfully finished fetch of the Access Token.');
_363        handler(response.token);
_363      })
_363      .fail(function(error) {
_363        console.log('Failed to fetch the Access Token with error: ' + error);
_363      });
_363  }
_363
_363  function connectMessagingClient(token) {
_363    // Initialize the Chat messaging client
_363    tc.accessManager = new Twilio.AccessManager(token);
_363    Twilio.Chat.Client.create(token).then(function(client) {
_363      tc.messagingClient = client;
_363      updateConnectedUI();
_363      tc.loadChannelList(tc.joinGeneralChannel);
_363      tc.messagingClient.on('channelAdded', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('channelRemoved', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('tokenExpired', refreshToken);
_363    });
_363  }
_363
_363  function refreshToken() {
_363    fetchAccessToken(tc.username, setNewToken);
_363  }
_363
_363  function setNewToken(tokenResponse) {
_363    tc.accessManager.updateToken(tokenResponse.token);
_363  }
_363
_363  function updateConnectedUI() {
_363    $('#username-span').text(tc.username);
_363    $statusRow.addClass('connected').removeClass('disconnected');
_363    tc.$messageList.addClass('connected').removeClass('disconnected');
_363    $connectPanel.addClass('connected').removeClass('disconnected');
_363    $inputText.addClass('with-shadow');
_363    $typingRow.addClass('connected').removeClass('disconnected');
_363  }
_363
_363  tc.loadChannelList = function(handler) {
_363    if (tc.messagingClient === undefined) {
_363      console.log('Client is not initialized');
_363      return;
_363    }
_363
_363    tc.messagingClient.getPublicChannelDescriptors().then(function(channels) {
_363      tc.channelArray = tc.sortChannelsByName(channels.items);
_363      $channelList.text('');
_363      tc.channelArray.forEach(addChannel);
_363      if (typeof handler === 'function') {
_363        handler();
_363      }
_363    });
_363  };
_363
_363  tc.joinGeneralChannel = function() {
_363    console.log('Attempting to join "general" chat channel...');
_363    if (!tc.generalChannel) {
_363      // If it doesn't exist, let's create it
_363      tc.messagingClient.createChannel({
_363        uniqueName: GENERAL_CHANNEL_UNIQUE_NAME,
_363        friendlyName: GENERAL_CHANNEL_NAME
_363      }).then(function(channel) {
_363        console.log('Created general channel');
_363        tc.generalChannel = channel;
_363        tc.loadChannelList(tc.joinGeneralChannel);
_363      });
_363    }
_363    else {
_363      console.log('Found general channel:');
_363      setupChannel(tc.generalChannel);
_363    }
_363  };
_363
_363  function initChannel(channel) {
_363    console.log('Initialized channel ' + channel.friendlyName);
_363    return tc.messagingClient.getChannelBySid(channel.sid);
_363  }
_363
_363  function joinChannel(_channel) {
_363    return _channel.join()
_363      .then(function(joinedChannel) {
_363        console.log('Joined channel ' + joinedChannel.friendlyName);
_363        updateChannelUI(_channel);
_363        tc.currentChannel = _channel;
_363        tc.loadMessages();
_363        return joinedChannel;
_363      });
_363  }
_363
_363  function initChannelEvents() {
_363    console.log(tc.currentChannel.friendlyName + ' ready.');
_363    tc.currentChannel.on('messageAdded', tc.addMessageToList);
_363    tc.currentChannel.on('typingStarted', showTypingStarted);
_363    tc.currentChannel.on('typingEnded', hideTypingStarted);
_363    tc.currentChannel.on('memberJoined', notifyMemberJoined);
_363    tc.currentChannel.on('memberLeft', notifyMemberLeft);
_363    $inputText.prop('disabled', false).focus();
_363  }
_363
_363  function setupChannel(channel) {
_363    return leaveCurrentChannel()
_363      .then(function() {
_363        return initChannel(channel);
_363      })
_363      .then(function(_channel) {
_363        return joinChannel(_channel);
_363      })
_363      .then(initChannelEvents);
_363  }
_363
_363  tc.loadMessages = function() {
_363    tc.currentChannel.getMessages(MESSAGES_HISTORY_LIMIT)
_363      .then(function(messages) {
_363        messages.items.forEach(tc.addMessageToList);
_363    });
_363  };
_363
_363  function leaveCurrentChannel() {
_363    if (tc.currentChannel) {
_363      return tc.currentChannel.leave().then(function(leftChannel) {
_363        console.log('left ' + leftChannel.friendlyName);
_363        leftChannel.removeListener('messageAdded', tc.addMessageToList);
_363        leftChannel.removeListener('typingStarted', showTypingStarted);
_363        leftChannel.removeListener('typingEnded', hideTypingStarted);
_363        leftChannel.removeListener('memberJoined', notifyMemberJoined);
_363        leftChannel.removeListener('memberLeft', notifyMemberLeft);
_363      });
_363    } else {
_363      return Promise.resolve();
_363    }
_363  }
_363
_363  tc.addMessageToList = function(message) {
_363    var rowDiv = $('<div>').addClass('row no-margin');
_363    rowDiv.loadTemplate($('#message-template'), {
_363      username: message.author,
_363      date: dateFormatter.getTodayDate(message.dateCreated),
_363      body: message.body
_363    });
_363    if (message.author === tc.username) {
_363      rowDiv.addClass('own-message');
_363    }
_363
_363    tc.$messageList.append(rowDiv);
_363    scrollToMessageListBottom();
_363  };
_363
_363  function notifyMemberJoined(member) {
_363    notify(member.identity + ' joined the channel')
_363  }
_363
_363  function notifyMemberLeft(member) {
_363    notify(member.identity + ' left the channel');
_363  }
_363
_363  function notify(message) {
_363    var row = $('<div>').addClass('col-md-12');
_363    row.loadTemplate('#member-notification-template', {
_363      status: message
_363    });
_363    tc.$messageList.append(row);
_363    scrollToMessageListBottom();
_363  }
_363
_363  function showTypingStarted(member) {
_363    $typingPlaceholder.text(member.identity + ' is typing...');
_363  }
_363
_363  function hideTypingStarted(member) {
_363    $typingPlaceholder.text('');
_363  }
_363
_363  function scrollToMessageListBottom() {
_363    tc.$messageList.scrollTop(tc.$messageList[0].scrollHeight);
_363  }
_363
_363  function updateChannelUI(selectedChannel) {
_363    var channelElements = $('.channel-element').toArray();
_363    var channelElement = channelElements.filter(function(element) {
_363      return $(element).data().sid === selectedChannel.sid;
_363    });
_363    channelElement = $(channelElement);
_363    if (tc.currentChannelContainer === undefined && selectedChannel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.currentChannelContainer = channelElement;
_363    }
_363    tc.currentChannelContainer.removeClass('selected-channel').addClass('unselected-channel');
_363    channelElement.removeClass('unselected-channel').addClass('selected-channel');
_363    tc.currentChannelContainer = channelElement;
_363  }
_363
_363  function showAddChannelInput() {
_363    if (tc.messagingClient) {
_363      $newChannelInputRow.addClass('showing').removeClass('not-showing');
_363      $channelList.addClass('showing').removeClass('not-showing');
_363      $newChannelInput.focus();
_363    }
_363  }
_363
_363  function hideAddChannelInput() {
_363    $newChannelInputRow.addClass('not-showing').removeClass('showing');
_363    $channelList.addClass('not-showing').removeClass('showing');
_363    $newChannelInput.val('');
_363  }
_363
_363  function addChannel(channel) {
_363    if (channel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.generalChannel = channel;
_363    }
_363    var rowDiv = $('<div>').addClass('row channel-row');
_363    rowDiv.loadTemplate('#channel-template', {
_363      channelName: channel.friendlyName
_363    });
_363
_363    var channelP = rowDiv.children().children().first();
_363
_363    rowDiv.on('click', selectChannel);
_363    channelP.data('sid', channel.sid);
_363    if (tc.currentChannel && channel.sid === tc.currentChannel.sid) {
_363      tc.currentChannelContainer = channelP;
_363      channelP.addClass('selected-channel');
_363    }
_363    else {
_363      channelP.addClass('unselected-channel')
_363    }
_363
_363    $channelList.append(rowDiv);
_363  }
_363
_363  function deleteCurrentChannel() {
_363    if (!tc.currentChannel) {
_363      return;
_363    }
_363    if (tc.currentChannel.sid === tc.generalChannel.sid) {
_363      alert('You cannot delete the general channel');
_363      return;
_363    }
_363    tc.currentChannel.delete().then(function(channel) {
_363      console.log('channel: '+ channel.friendlyName + ' deleted');
_363      setupChannel(tc.generalChannel);
_363    });
_363  }
_363
_363  function selectChannel(event) {
_363    var target = $(event.target);
_363    var channelSid = target.data().sid;
_363    var selectedChannel = tc.channelArray.filter(function(channel) {
_363      return channel.sid === channelSid;
_363    })[0];
_363    if (selectedChannel === tc.currentChannel) {
_363      return;
_363    }
_363    setupChannel(selectedChannel);
_363  };
_363
_363  function disconnectClient() {
_363    leaveCurrentChannel();
_363    $channelList.text('');
_363    tc.$messageList.text('');
_363    channels = undefined;
_363    $statusRow.addClass('disconnected').removeClass('connected');
_363    tc.$messageList.addClass('disconnected').removeClass('connected');
_363    $connectPanel.addClass('disconnected').removeClass('connected');
_363    $inputText.removeClass('with-shadow');
_363    $typingRow.addClass('disconnected').removeClass('connected');
_363  }
_363
_363  tc.sortChannelsByName = function(channels) {
_363    return channels.sort(function(a, b) {
_363      if (a.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return -1;
_363      }
_363      if (b.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return 1;
_363      }
_363      return a.friendlyName.localeCompare(b.friendlyName);
_363    });
_363  };
_363
_363  return tc;
_363})();

Next, we need a default channel.

Join the General Channel

This application will try to join a channel called "General Channel" when it starts. If the channel doesn't exist, we'll create one with that name. The scope of this example application will show you how to work only with public channels, but the Programmable Chat client allows you to create private channels and handles invitations.

Notice we set a unique name for the general channel as we don't want to create a new general channel every time we start the application.

Join the General Channel

src/main/webapp/js/twiliochat.js


_363var twiliochat = (function() {
_363  var tc = {};
_363
_363  var GENERAL_CHANNEL_UNIQUE_NAME = 'general';
_363  var GENERAL_CHANNEL_NAME = 'General Channel';
_363  var MESSAGES_HISTORY_LIMIT = 50;
_363
_363  var $channelList;
_363  var $inputText;
_363  var $usernameInput;
_363  var $statusRow;
_363  var $connectPanel;
_363  var $newChannelInputRow;
_363  var $newChannelInput;
_363  var $typingRow;
_363  var $typingPlaceholder;
_363
_363  $(document).ready(function() {
_363    tc.$messageList = $('#message-list');
_363    $channelList = $('#channel-list');
_363    $inputText = $('#input-text');
_363    $usernameInput = $('#username-input');
_363    $statusRow = $('#status-row');
_363    $connectPanel = $('#connect-panel');
_363    $newChannelInputRow = $('#new-channel-input-row');
_363    $newChannelInput = $('#new-channel-input');
_363    $typingRow = $('#typing-row');
_363    $typingPlaceholder = $('#typing-placeholder');
_363    $usernameInput.focus();
_363    $usernameInput.on('keypress', handleUsernameInputKeypress);
_363    $inputText.on('keypress', handleInputTextKeypress);
_363    $newChannelInput.on('keypress', tc.handleNewChannelInputKeypress);
_363    $('#connect-image').on('click', connectClientWithUsername);
_363    $('#add-channel-image').on('click', showAddChannelInput);
_363    $('#leave-span').on('click', disconnectClient);
_363    $('#delete-channel-span').on('click', deleteCurrentChannel);
_363  });
_363
_363  function handleUsernameInputKeypress(event) {
_363    if (event.keyCode === 13){
_363      connectClientWithUsername();
_363    }
_363  }
_363
_363  function handleInputTextKeypress(event) {
_363    if (event.keyCode === 13) {
_363      tc.currentChannel.sendMessage($(this).val());
_363      event.preventDefault();
_363      $(this).val('');
_363    }
_363    else {
_363      notifyTyping();
_363    }
_363  }
_363
_363  var notifyTyping = $.throttle(function() {
_363    tc.currentChannel.typing();
_363  }, 1000);
_363
_363  tc.handleNewChannelInputKeypress = function(event) {
_363    if (event.keyCode === 13) {
_363      tc.messagingClient.createChannel({
_363        friendlyName: $newChannelInput.val()
_363      }).then(hideAddChannelInput);
_363      $(this).val('');
_363      event.preventDefault();
_363    }
_363  };
_363
_363  function connectClientWithUsername() {
_363    var usernameText = $usernameInput.val();
_363    $usernameInput.val('');
_363    if (usernameText == '') {
_363      alert('Username cannot be empty');
_363      return;
_363    }
_363    tc.username = usernameText;
_363    fetchAccessToken(tc.username, connectMessagingClient);
_363  }
_363
_363  function fetchAccessToken(username, handler) {
_363    $.post('/twiliochat-servlets/token', {identity: username}, null, 'json')
_363      .done(function(response) {
_363        console.log('Successfully finished fetch of the Access Token.');
_363        handler(response.token);
_363      })
_363      .fail(function(error) {
_363        console.log('Failed to fetch the Access Token with error: ' + error);
_363      });
_363  }
_363
_363  function connectMessagingClient(token) {
_363    // Initialize the Chat messaging client
_363    tc.accessManager = new Twilio.AccessManager(token);
_363    Twilio.Chat.Client.create(token).then(function(client) {
_363      tc.messagingClient = client;
_363      updateConnectedUI();
_363      tc.loadChannelList(tc.joinGeneralChannel);
_363      tc.messagingClient.on('channelAdded', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('channelRemoved', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('tokenExpired', refreshToken);
_363    });
_363  }
_363
_363  function refreshToken() {
_363    fetchAccessToken(tc.username, setNewToken);
_363  }
_363
_363  function setNewToken(tokenResponse) {
_363    tc.accessManager.updateToken(tokenResponse.token);
_363  }
_363
_363  function updateConnectedUI() {
_363    $('#username-span').text(tc.username);
_363    $statusRow.addClass('connected').removeClass('disconnected');
_363    tc.$messageList.addClass('connected').removeClass('disconnected');
_363    $connectPanel.addClass('connected').removeClass('disconnected');
_363    $inputText.addClass('with-shadow');
_363    $typingRow.addClass('connected').removeClass('disconnected');
_363  }
_363
_363  tc.loadChannelList = function(handler) {
_363    if (tc.messagingClient === undefined) {
_363      console.log('Client is not initialized');
_363      return;
_363    }
_363
_363    tc.messagingClient.getPublicChannelDescriptors().then(function(channels) {
_363      tc.channelArray = tc.sortChannelsByName(channels.items);
_363      $channelList.text('');
_363      tc.channelArray.forEach(addChannel);
_363      if (typeof handler === 'function') {
_363        handler();
_363      }
_363    });
_363  };
_363
_363  tc.joinGeneralChannel = function() {
_363    console.log('Attempting to join "general" chat channel...');
_363    if (!tc.generalChannel) {
_363      // If it doesn't exist, let's create it
_363      tc.messagingClient.createChannel({
_363        uniqueName: GENERAL_CHANNEL_UNIQUE_NAME,
_363        friendlyName: GENERAL_CHANNEL_NAME
_363      }).then(function(channel) {
_363        console.log('Created general channel');
_363        tc.generalChannel = channel;
_363        tc.loadChannelList(tc.joinGeneralChannel);
_363      });
_363    }
_363    else {
_363      console.log('Found general channel:');
_363      setupChannel(tc.generalChannel);
_363    }
_363  };
_363
_363  function initChannel(channel) {
_363    console.log('Initialized channel ' + channel.friendlyName);
_363    return tc.messagingClient.getChannelBySid(channel.sid);
_363  }
_363
_363  function joinChannel(_channel) {
_363    return _channel.join()
_363      .then(function(joinedChannel) {
_363        console.log('Joined channel ' + joinedChannel.friendlyName);
_363        updateChannelUI(_channel);
_363        tc.currentChannel = _channel;
_363        tc.loadMessages();
_363        return joinedChannel;
_363      });
_363  }
_363
_363  function initChannelEvents() {
_363    console.log(tc.currentChannel.friendlyName + ' ready.');
_363    tc.currentChannel.on('messageAdded', tc.addMessageToList);
_363    tc.currentChannel.on('typingStarted', showTypingStarted);
_363    tc.currentChannel.on('typingEnded', hideTypingStarted);
_363    tc.currentChannel.on('memberJoined', notifyMemberJoined);
_363    tc.currentChannel.on('memberLeft', notifyMemberLeft);
_363    $inputText.prop('disabled', false).focus();
_363  }
_363
_363  function setupChannel(channel) {
_363    return leaveCurrentChannel()
_363      .then(function() {
_363        return initChannel(channel);
_363      })
_363      .then(function(_channel) {
_363        return joinChannel(_channel);
_363      })
_363      .then(initChannelEvents);
_363  }
_363
_363  tc.loadMessages = function() {
_363    tc.currentChannel.getMessages(MESSAGES_HISTORY_LIMIT)
_363      .then(function(messages) {
_363        messages.items.forEach(tc.addMessageToList);
_363    });
_363  };
_363
_363  function leaveCurrentChannel() {
_363    if (tc.currentChannel) {
_363      return tc.currentChannel.leave().then(function(leftChannel) {
_363        console.log('left ' + leftChannel.friendlyName);
_363        leftChannel.removeListener('messageAdded', tc.addMessageToList);
_363        leftChannel.removeListener('typingStarted', showTypingStarted);
_363        leftChannel.removeListener('typingEnded', hideTypingStarted);
_363        leftChannel.removeListener('memberJoined', notifyMemberJoined);
_363        leftChannel.removeListener('memberLeft', notifyMemberLeft);
_363      });
_363    } else {
_363      return Promise.resolve();
_363    }
_363  }
_363
_363  tc.addMessageToList = function(message) {
_363    var rowDiv = $('<div>').addClass('row no-margin');
_363    rowDiv.loadTemplate($('#message-template'), {
_363      username: message.author,
_363      date: dateFormatter.getTodayDate(message.dateCreated),
_363      body: message.body
_363    });
_363    if (message.author === tc.username) {
_363      rowDiv.addClass('own-message');
_363    }
_363
_363    tc.$messageList.append(rowDiv);
_363    scrollToMessageListBottom();
_363  };
_363
_363  function notifyMemberJoined(member) {
_363    notify(member.identity + ' joined the channel')
_363  }
_363
_363  function notifyMemberLeft(member) {
_363    notify(member.identity + ' left the channel');
_363  }
_363
_363  function notify(message) {
_363    var row = $('<div>').addClass('col-md-12');
_363    row.loadTemplate('#member-notification-template', {
_363      status: message
_363    });
_363    tc.$messageList.append(row);
_363    scrollToMessageListBottom();
_363  }
_363
_363  function showTypingStarted(member) {
_363    $typingPlaceholder.text(member.identity + ' is typing...');
_363  }
_363
_363  function hideTypingStarted(member) {
_363    $typingPlaceholder.text('');
_363  }
_363
_363  function scrollToMessageListBottom() {
_363    tc.$messageList.scrollTop(tc.$messageList[0].scrollHeight);
_363  }
_363
_363  function updateChannelUI(selectedChannel) {
_363    var channelElements = $('.channel-element').toArray();
_363    var channelElement = channelElements.filter(function(element) {
_363      return $(element).data().sid === selectedChannel.sid;
_363    });
_363    channelElement = $(channelElement);
_363    if (tc.currentChannelContainer === undefined && selectedChannel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.currentChannelContainer = channelElement;
_363    }
_363    tc.currentChannelContainer.removeClass('selected-channel').addClass('unselected-channel');
_363    channelElement.removeClass('unselected-channel').addClass('selected-channel');
_363    tc.currentChannelContainer = channelElement;
_363  }
_363
_363  function showAddChannelInput() {
_363    if (tc.messagingClient) {
_363      $newChannelInputRow.addClass('showing').removeClass('not-showing');
_363      $channelList.addClass('showing').removeClass('not-showing');
_363      $newChannelInput.focus();
_363    }
_363  }
_363
_363  function hideAddChannelInput() {
_363    $newChannelInputRow.addClass('not-showing').removeClass('showing');
_363    $channelList.addClass('not-showing').removeClass('showing');
_363    $newChannelInput.val('');
_363  }
_363
_363  function addChannel(channel) {
_363    if (channel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.generalChannel = channel;
_363    }
_363    var rowDiv = $('<div>').addClass('row channel-row');
_363    rowDiv.loadTemplate('#channel-template', {
_363      channelName: channel.friendlyName
_363    });
_363
_363    var channelP = rowDiv.children().children().first();
_363
_363    rowDiv.on('click', selectChannel);
_363    channelP.data('sid', channel.sid);
_363    if (tc.currentChannel && channel.sid === tc.currentChannel.sid) {
_363      tc.currentChannelContainer = channelP;
_363      channelP.addClass('selected-channel');
_363    }
_363    else {
_363      channelP.addClass('unselected-channel')
_363    }
_363
_363    $channelList.append(rowDiv);
_363  }
_363
_363  function deleteCurrentChannel() {
_363    if (!tc.currentChannel) {
_363      return;
_363    }
_363    if (tc.currentChannel.sid === tc.generalChannel.sid) {
_363      alert('You cannot delete the general channel');
_363      return;
_363    }
_363    tc.currentChannel.delete().then(function(channel) {
_363      console.log('channel: '+ channel.friendlyName + ' deleted');
_363      setupChannel(tc.generalChannel);
_363    });
_363  }
_363
_363  function selectChannel(event) {
_363    var target = $(event.target);
_363    var channelSid = target.data().sid;
_363    var selectedChannel = tc.channelArray.filter(function(channel) {
_363      return channel.sid === channelSid;
_363    })[0];
_363    if (selectedChannel === tc.currentChannel) {
_363      return;
_363    }
_363    setupChannel(selectedChannel);
_363  };
_363
_363  function disconnectClient() {
_363    leaveCurrentChannel();
_363    $channelList.text('');
_363    tc.$messageList.text('');
_363    channels = undefined;
_363    $statusRow.addClass('disconnected').removeClass('connected');
_363    tc.$messageList.addClass('disconnected').removeClass('connected');
_363    $connectPanel.addClass('disconnected').removeClass('connected');
_363    $inputText.removeClass('with-shadow');
_363    $typingRow.addClass('disconnected').removeClass('connected');
_363  }
_363
_363  tc.sortChannelsByName = function(channels) {
_363    return channels.sort(function(a, b) {
_363      if (a.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return -1;
_363      }
_363      if (b.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return 1;
_363      }
_363      return a.friendlyName.localeCompare(b.friendlyName);
_363    });
_363  };
_363
_363  return tc;
_363})();

Now let's listen for some channel events.

Listen to Channel Events

Next we listen for channel events. In our case, we're setting listeners to the following events:

messageAdded : When another member sends a message to the channel you are connected to.
typingStarted : When another member is typing a message on the channel that you are connected to.
typingEnded : When another member stops typing a message on the channel that you are connected to.
memberJoined : When another member joins the channel that you are connected to.
memberLeft : When another member leaves the channel that you are connected to.

We register a different function to handle each particular event.

Listen to Channel Events

src/main/webapp/js/twiliochat.js


_363var twiliochat = (function() {
_363  var tc = {};
_363
_363  var GENERAL_CHANNEL_UNIQUE_NAME = 'general';
_363  var GENERAL_CHANNEL_NAME = 'General Channel';
_363  var MESSAGES_HISTORY_LIMIT = 50;
_363
_363  var $channelList;
_363  var $inputText;
_363  var $usernameInput;
_363  var $statusRow;
_363  var $connectPanel;
_363  var $newChannelInputRow;
_363  var $newChannelInput;
_363  var $typingRow;
_363  var $typingPlaceholder;
_363
_363  $(document).ready(function() {
_363    tc.$messageList = $('#message-list');
_363    $channelList = $('#channel-list');
_363    $inputText = $('#input-text');
_363    $usernameInput = $('#username-input');
_363    $statusRow = $('#status-row');
_363    $connectPanel = $('#connect-panel');
_363    $newChannelInputRow = $('#new-channel-input-row');
_363    $newChannelInput = $('#new-channel-input');
_363    $typingRow = $('#typing-row');
_363    $typingPlaceholder = $('#typing-placeholder');
_363    $usernameInput.focus();
_363    $usernameInput.on('keypress', handleUsernameInputKeypress);
_363    $inputText.on('keypress', handleInputTextKeypress);
_363    $newChannelInput.on('keypress', tc.handleNewChannelInputKeypress);
_363    $('#connect-image').on('click', connectClientWithUsername);
_363    $('#add-channel-image').on('click', showAddChannelInput);
_363    $('#leave-span').on('click', disconnectClient);
_363    $('#delete-channel-span').on('click', deleteCurrentChannel);
_363  });
_363
_363  function handleUsernameInputKeypress(event) {
_363    if (event.keyCode === 13){
_363      connectClientWithUsername();
_363    }
_363  }
_363
_363  function handleInputTextKeypress(event) {
_363    if (event.keyCode === 13) {
_363      tc.currentChannel.sendMessage($(this).val());
_363      event.preventDefault();
_363      $(this).val('');
_363    }
_363    else {
_363      notifyTyping();
_363    }
_363  }
_363
_363  var notifyTyping = $.throttle(function() {
_363    tc.currentChannel.typing();
_363  }, 1000);
_363
_363  tc.handleNewChannelInputKeypress = function(event) {
_363    if (event.keyCode === 13) {
_363      tc.messagingClient.createChannel({
_363        friendlyName: $newChannelInput.val()
_363      }).then(hideAddChannelInput);
_363      $(this).val('');
_363      event.preventDefault();
_363    }
_363  };
_363
_363  function connectClientWithUsername() {
_363    var usernameText = $usernameInput.val();
_363    $usernameInput.val('');
_363    if (usernameText == '') {
_363      alert('Username cannot be empty');
_363      return;
_363    }
_363    tc.username = usernameText;
_363    fetchAccessToken(tc.username, connectMessagingClient);
_363  }
_363
_363  function fetchAccessToken(username, handler) {
_363    $.post('/twiliochat-servlets/token', {identity: username}, null, 'json')
_363      .done(function(response) {
_363        console.log('Successfully finished fetch of the Access Token.');
_363        handler(response.token);
_363      })
_363      .fail(function(error) {
_363        console.log('Failed to fetch the Access Token with error: ' + error);
_363      });
_363  }
_363
_363  function connectMessagingClient(token) {
_363    // Initialize the Chat messaging client
_363    tc.accessManager = new Twilio.AccessManager(token);
_363    Twilio.Chat.Client.create(token).then(function(client) {
_363      tc.messagingClient = client;
_363      updateConnectedUI();
_363      tc.loadChannelList(tc.joinGeneralChannel);
_363      tc.messagingClient.on('channelAdded', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('channelRemoved', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('tokenExpired', refreshToken);
_363    });
_363  }
_363
_363  function refreshToken() {
_363    fetchAccessToken(tc.username, setNewToken);
_363  }
_363
_363  function setNewToken(tokenResponse) {
_363    tc.accessManager.updateToken(tokenResponse.token);
_363  }
_363
_363  function updateConnectedUI() {
_363    $('#username-span').text(tc.username);
_363    $statusRow.addClass('connected').removeClass('disconnected');
_363    tc.$messageList.addClass('connected').removeClass('disconnected');
_363    $connectPanel.addClass('connected').removeClass('disconnected');
_363    $inputText.addClass('with-shadow');
_363    $typingRow.addClass('connected').removeClass('disconnected');
_363  }
_363
_363  tc.loadChannelList = function(handler) {
_363    if (tc.messagingClient === undefined) {
_363      console.log('Client is not initialized');
_363      return;
_363    }
_363
_363    tc.messagingClient.getPublicChannelDescriptors().then(function(channels) {
_363      tc.channelArray = tc.sortChannelsByName(channels.items);
_363      $channelList.text('');
_363      tc.channelArray.forEach(addChannel);
_363      if (typeof handler === 'function') {
_363        handler();
_363      }
_363    });
_363  };
_363
_363  tc.joinGeneralChannel = function() {
_363    console.log('Attempting to join "general" chat channel...');
_363    if (!tc.generalChannel) {
_363      // If it doesn't exist, let's create it
_363      tc.messagingClient.createChannel({
_363        uniqueName: GENERAL_CHANNEL_UNIQUE_NAME,
_363        friendlyName: GENERAL_CHANNEL_NAME
_363      }).then(function(channel) {
_363        console.log('Created general channel');
_363        tc.generalChannel = channel;
_363        tc.loadChannelList(tc.joinGeneralChannel);
_363      });
_363    }
_363    else {
_363      console.log('Found general channel:');
_363      setupChannel(tc.generalChannel);
_363    }
_363  };
_363
_363  function initChannel(channel) {
_363    console.log('Initialized channel ' + channel.friendlyName);
_363    return tc.messagingClient.getChannelBySid(channel.sid);
_363  }
_363
_363  function joinChannel(_channel) {
_363    return _channel.join()
_363      .then(function(joinedChannel) {
_363        console.log('Joined channel ' + joinedChannel.friendlyName);
_363        updateChannelUI(_channel);
_363        tc.currentChannel = _channel;
_363        tc.loadMessages();
_363        return joinedChannel;
_363      });
_363  }
_363
_363  function initChannelEvents() {
_363    console.log(tc.currentChannel.friendlyName + ' ready.');
_363    tc.currentChannel.on('messageAdded', tc.addMessageToList);
_363    tc.currentChannel.on('typingStarted', showTypingStarted);
_363    tc.currentChannel.on('typingEnded', hideTypingStarted);
_363    tc.currentChannel.on('memberJoined', notifyMemberJoined);
_363    tc.currentChannel.on('memberLeft', notifyMemberLeft);
_363    $inputText.prop('disabled', false).focus();
_363  }
_363
_363  function setupChannel(channel) {
_363    return leaveCurrentChannel()
_363      .then(function() {
_363        return initChannel(channel);
_363      })
_363      .then(function(_channel) {
_363        return joinChannel(_channel);
_363      })
_363      .then(initChannelEvents);
_363  }
_363
_363  tc.loadMessages = function() {
_363    tc.currentChannel.getMessages(MESSAGES_HISTORY_LIMIT)
_363      .then(function(messages) {
_363        messages.items.forEach(tc.addMessageToList);
_363    });
_363  };
_363
_363  function leaveCurrentChannel() {
_363    if (tc.currentChannel) {
_363      return tc.currentChannel.leave().then(function(leftChannel) {
_363        console.log('left ' + leftChannel.friendlyName);
_363        leftChannel.removeListener('messageAdded', tc.addMessageToList);
_363        leftChannel.removeListener('typingStarted', showTypingStarted);
_363        leftChannel.removeListener('typingEnded', hideTypingStarted);
_363        leftChannel.removeListener('memberJoined', notifyMemberJoined);
_363        leftChannel.removeListener('memberLeft', notifyMemberLeft);
_363      });
_363    } else {
_363      return Promise.resolve();
_363    }
_363  }
_363
_363  tc.addMessageToList = function(message) {
_363    var rowDiv = $('<div>').addClass('row no-margin');
_363    rowDiv.loadTemplate($('#message-template'), {
_363      username: message.author,
_363      date: dateFormatter.getTodayDate(message.dateCreated),
_363      body: message.body
_363    });
_363    if (message.author === tc.username) {
_363      rowDiv.addClass('own-message');
_363    }
_363
_363    tc.$messageList.append(rowDiv);
_363    scrollToMessageListBottom();
_363  };
_363
_363  function notifyMemberJoined(member) {
_363    notify(member.identity + ' joined the channel')
_363  }
_363
_363  function notifyMemberLeft(member) {
_363    notify(member.identity + ' left the channel');
_363  }
_363
_363  function notify(message) {
_363    var row = $('<div>').addClass('col-md-12');
_363    row.loadTemplate('#member-notification-template', {
_363      status: message
_363    });
_363    tc.$messageList.append(row);
_363    scrollToMessageListBottom();
_363  }
_363
_363  function showTypingStarted(member) {
_363    $typingPlaceholder.text(member.identity + ' is typing...');
_363  }
_363
_363  function hideTypingStarted(member) {
_363    $typingPlaceholder.text('');
_363  }
_363
_363  function scrollToMessageListBottom() {
_363    tc.$messageList.scrollTop(tc.$messageList[0].scrollHeight);
_363  }
_363
_363  function updateChannelUI(selectedChannel) {
_363    var channelElements = $('.channel-element').toArray();
_363    var channelElement = channelElements.filter(function(element) {
_363      return $(element).data().sid === selectedChannel.sid;
_363    });
_363    channelElement = $(channelElement);
_363    if (tc.currentChannelContainer === undefined && selectedChannel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.currentChannelContainer = channelElement;
_363    }
_363    tc.currentChannelContainer.removeClass('selected-channel').addClass('unselected-channel');
_363    channelElement.removeClass('unselected-channel').addClass('selected-channel');
_363    tc.currentChannelContainer = channelElement;
_363  }
_363
_363  function showAddChannelInput() {
_363    if (tc.messagingClient) {
_363      $newChannelInputRow.addClass('showing').removeClass('not-showing');
_363      $channelList.addClass('showing').removeClass('not-showing');
_363      $newChannelInput.focus();
_363    }
_363  }
_363
_363  function hideAddChannelInput() {
_363    $newChannelInputRow.addClass('not-showing').removeClass('showing');
_363    $channelList.addClass('not-showing').removeClass('showing');
_363    $newChannelInput.val('');
_363  }
_363
_363  function addChannel(channel) {
_363    if (channel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.generalChannel = channel;
_363    }
_363    var rowDiv = $('<div>').addClass('row channel-row');
_363    rowDiv.loadTemplate('#channel-template', {
_363      channelName: channel.friendlyName
_363    });
_363
_363    var channelP = rowDiv.children().children().first();
_363
_363    rowDiv.on('click', selectChannel);
_363    channelP.data('sid', channel.sid);
_363    if (tc.currentChannel && channel.sid === tc.currentChannel.sid) {
_363      tc.currentChannelContainer = channelP;
_363      channelP.addClass('selected-channel');
_363    }
_363    else {
_363      channelP.addClass('unselected-channel')
_363    }
_363
_363    $channelList.append(rowDiv);
_363  }
_363
_363  function deleteCurrentChannel() {
_363    if (!tc.currentChannel) {
_363      return;
_363    }
_363    if (tc.currentChannel.sid === tc.generalChannel.sid) {
_363      alert('You cannot delete the general channel');
_363      return;
_363    }
_363    tc.currentChannel.delete().then(function(channel) {
_363      console.log('channel: '+ channel.friendlyName + ' deleted');
_363      setupChannel(tc.generalChannel);
_363    });
_363  }
_363
_363  function selectChannel(event) {
_363    var target = $(event.target);
_363    var channelSid = target.data().sid;
_363    var selectedChannel = tc.channelArray.filter(function(channel) {
_363      return channel.sid === channelSid;
_363    })[0];
_363    if (selectedChannel === tc.currentChannel) {
_363      return;
_363    }
_363    setupChannel(selectedChannel);
_363  };
_363
_363  function disconnectClient() {
_363    leaveCurrentChannel();
_363    $channelList.text('');
_363    tc.$messageList.text('');
_363    channels = undefined;
_363    $statusRow.addClass('disconnected').removeClass('connected');
_363    tc.$messageList.addClass('disconnected').removeClass('connected');
_363    $connectPanel.addClass('disconnected').removeClass('connected');
_363    $inputText.removeClass('with-shadow');
_363    $typingRow.addClass('disconnected').removeClass('connected');
_363  }
_363
_363  tc.sortChannelsByName = function(channels) {
_363    return channels.sort(function(a, b) {
_363      if (a.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return -1;
_363      }
_363      if (b.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return 1;
_363      }
_363      return a.friendlyName.localeCompare(b.friendlyName);
_363    });
_363  };
_363
_363  return tc;
_363})();

The client emits events as well. Let's see how we can listen to those events as well.

Listen to Client Events

Just like with channels, we can register handlers for events on the Client:

channelAdded : When a channel becomes visible to the Client.
channelRemoved : When a channel is no longer visible to the Client.
tokenExpired : When the supplied token expires.

Listen to Client Events

src/main/webapp/js/twiliochat.js


_363var twiliochat = (function() {
_363  var tc = {};
_363
_363  var GENERAL_CHANNEL_UNIQUE_NAME = 'general';
_363  var GENERAL_CHANNEL_NAME = 'General Channel';
_363  var MESSAGES_HISTORY_LIMIT = 50;
_363
_363  var $channelList;
_363  var $inputText;
_363  var $usernameInput;
_363  var $statusRow;
_363  var $connectPanel;
_363  var $newChannelInputRow;
_363  var $newChannelInput;
_363  var $typingRow;
_363  var $typingPlaceholder;
_363
_363  $(document).ready(function() {
_363    tc.$messageList = $('#message-list');
_363    $channelList = $('#channel-list');
_363    $inputText = $('#input-text');
_363    $usernameInput = $('#username-input');
_363    $statusRow = $('#status-row');
_363    $connectPanel = $('#connect-panel');
_363    $newChannelInputRow = $('#new-channel-input-row');
_363    $newChannelInput = $('#new-channel-input');
_363    $typingRow = $('#typing-row');
_363    $typingPlaceholder = $('#typing-placeholder');
_363    $usernameInput.focus();
_363    $usernameInput.on('keypress', handleUsernameInputKeypress);
_363    $inputText.on('keypress', handleInputTextKeypress);
_363    $newChannelInput.on('keypress', tc.handleNewChannelInputKeypress);
_363    $('#connect-image').on('click', connectClientWithUsername);
_363    $('#add-channel-image').on('click', showAddChannelInput);
_363    $('#leave-span').on('click', disconnectClient);
_363    $('#delete-channel-span').on('click', deleteCurrentChannel);
_363  });
_363
_363  function handleUsernameInputKeypress(event) {
_363    if (event.keyCode === 13){
_363      connectClientWithUsername();
_363    }
_363  }
_363
_363  function handleInputTextKeypress(event) {
_363    if (event.keyCode === 13) {
_363      tc.currentChannel.sendMessage($(this).val());
_363      event.preventDefault();
_363      $(this).val('');
_363    }
_363    else {
_363      notifyTyping();
_363    }
_363  }
_363
_363  var notifyTyping = $.throttle(function() {
_363    tc.currentChannel.typing();
_363  }, 1000);
_363
_363  tc.handleNewChannelInputKeypress = function(event) {
_363    if (event.keyCode === 13) {
_363      tc.messagingClient.createChannel({
_363        friendlyName: $newChannelInput.val()
_363      }).then(hideAddChannelInput);
_363      $(this).val('');
_363      event.preventDefault();
_363    }
_363  };
_363
_363  function connectClientWithUsername() {
_363    var usernameText = $usernameInput.val();
_363    $usernameInput.val('');
_363    if (usernameText == '') {
_363      alert('Username cannot be empty');
_363      return;
_363    }
_363    tc.username = usernameText;
_363    fetchAccessToken(tc.username, connectMessagingClient);
_363  }
_363
_363  function fetchAccessToken(username, handler) {
_363    $.post('/twiliochat-servlets/token', {identity: username}, null, 'json')
_363      .done(function(response) {
_363        console.log('Successfully finished fetch of the Access Token.');
_363        handler(response.token);
_363      })
_363      .fail(function(error) {
_363        console.log('Failed to fetch the Access Token with error: ' + error);
_363      });
_363  }
_363
_363  function connectMessagingClient(token) {
_363    // Initialize the Chat messaging client
_363    tc.accessManager = new Twilio.AccessManager(token);
_363    Twilio.Chat.Client.create(token).then(function(client) {
_363      tc.messagingClient = client;
_363      updateConnectedUI();
_363      tc.loadChannelList(tc.joinGeneralChannel);
_363      tc.messagingClient.on('channelAdded', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('channelRemoved', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('tokenExpired', refreshToken);
_363    });
_363  }
_363
_363  function refreshToken() {
_363    fetchAccessToken(tc.username, setNewToken);
_363  }
_363
_363  function setNewToken(tokenResponse) {
_363    tc.accessManager.updateToken(tokenResponse.token);
_363  }
_363
_363  function updateConnectedUI() {
_363    $('#username-span').text(tc.username);
_363    $statusRow.addClass('connected').removeClass('disconnected');
_363    tc.$messageList.addClass('connected').removeClass('disconnected');
_363    $connectPanel.addClass('connected').removeClass('disconnected');
_363    $inputText.addClass('with-shadow');
_363    $typingRow.addClass('connected').removeClass('disconnected');
_363  }
_363
_363  tc.loadChannelList = function(handler) {
_363    if (tc.messagingClient === undefined) {
_363      console.log('Client is not initialized');
_363      return;
_363    }
_363
_363    tc.messagingClient.getPublicChannelDescriptors().then(function(channels) {
_363      tc.channelArray = tc.sortChannelsByName(channels.items);
_363      $channelList.text('');
_363      tc.channelArray.forEach(addChannel);
_363      if (typeof handler === 'function') {
_363        handler();
_363      }
_363    });
_363  };
_363
_363  tc.joinGeneralChannel = function() {
_363    console.log('Attempting to join "general" chat channel...');
_363    if (!tc.generalChannel) {
_363      // If it doesn't exist, let's create it
_363      tc.messagingClient.createChannel({
_363        uniqueName: GENERAL_CHANNEL_UNIQUE_NAME,
_363        friendlyName: GENERAL_CHANNEL_NAME
_363      }).then(function(channel) {
_363        console.log('Created general channel');
_363        tc.generalChannel = channel;
_363        tc.loadChannelList(tc.joinGeneralChannel);
_363      });
_363    }
_363    else {
_363      console.log('Found general channel:');
_363      setupChannel(tc.generalChannel);
_363    }
_363  };
_363
_363  function initChannel(channel) {
_363    console.log('Initialized channel ' + channel.friendlyName);
_363    return tc.messagingClient.getChannelBySid(channel.sid);
_363  }
_363
_363  function joinChannel(_channel) {
_363    return _channel.join()
_363      .then(function(joinedChannel) {
_363        console.log('Joined channel ' + joinedChannel.friendlyName);
_363        updateChannelUI(_channel);
_363        tc.currentChannel = _channel;
_363        tc.loadMessages();
_363        return joinedChannel;
_363      });
_363  }
_363
_363  function initChannelEvents() {
_363    console.log(tc.currentChannel.friendlyName + ' ready.');
_363    tc.currentChannel.on('messageAdded', tc.addMessageToList);
_363    tc.currentChannel.on('typingStarted', showTypingStarted);
_363    tc.currentChannel.on('typingEnded', hideTypingStarted);
_363    tc.currentChannel.on('memberJoined', notifyMemberJoined);
_363    tc.currentChannel.on('memberLeft', notifyMemberLeft);
_363    $inputText.prop('disabled', false).focus();
_363  }
_363
_363  function setupChannel(channel) {
_363    return leaveCurrentChannel()
_363      .then(function() {
_363        return initChannel(channel);
_363      })
_363      .then(function(_channel) {
_363        return joinChannel(_channel);
_363      })
_363      .then(initChannelEvents);
_363  }
_363
_363  tc.loadMessages = function() {
_363    tc.currentChannel.getMessages(MESSAGES_HISTORY_LIMIT)
_363      .then(function(messages) {
_363        messages.items.forEach(tc.addMessageToList);
_363    });
_363  };
_363
_363  function leaveCurrentChannel() {
_363    if (tc.currentChannel) {
_363      return tc.currentChannel.leave().then(function(leftChannel) {
_363        console.log('left ' + leftChannel.friendlyName);
_363        leftChannel.removeListener('messageAdded', tc.addMessageToList);
_363        leftChannel.removeListener('typingStarted', showTypingStarted);
_363        leftChannel.removeListener('typingEnded', hideTypingStarted);
_363        leftChannel.removeListener('memberJoined', notifyMemberJoined);
_363        leftChannel.removeListener('memberLeft', notifyMemberLeft);
_363      });
_363    } else {
_363      return Promise.resolve();
_363    }
_363  }
_363
_363  tc.addMessageToList = function(message) {
_363    var rowDiv = $('<div>').addClass('row no-margin');
_363    rowDiv.loadTemplate($('#message-template'), {
_363      username: message.author,
_363      date: dateFormatter.getTodayDate(message.dateCreated),
_363      body: message.body
_363    });
_363    if (message.author === tc.username) {
_363      rowDiv.addClass('own-message');
_363    }
_363
_363    tc.$messageList.append(rowDiv);
_363    scrollToMessageListBottom();
_363  };
_363
_363  function notifyMemberJoined(member) {
_363    notify(member.identity + ' joined the channel')
_363  }
_363
_363  function notifyMemberLeft(member) {
_363    notify(member.identity + ' left the channel');
_363  }
_363
_363  function notify(message) {
_363    var row = $('<div>').addClass('col-md-12');
_363    row.loadTemplate('#member-notification-template', {
_363      status: message
_363    });
_363    tc.$messageList.append(row);
_363    scrollToMessageListBottom();
_363  }
_363
_363  function showTypingStarted(member) {
_363    $typingPlaceholder.text(member.identity + ' is typing...');
_363  }
_363
_363  function hideTypingStarted(member) {
_363    $typingPlaceholder.text('');
_363  }
_363
_363  function scrollToMessageListBottom() {
_363    tc.$messageList.scrollTop(tc.$messageList[0].scrollHeight);
_363  }
_363
_363  function updateChannelUI(selectedChannel) {
_363    var channelElements = $('.channel-element').toArray();
_363    var channelElement = channelElements.filter(function(element) {
_363      return $(element).data().sid === selectedChannel.sid;
_363    });
_363    channelElement = $(channelElement);
_363    if (tc.currentChannelContainer === undefined && selectedChannel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.currentChannelContainer = channelElement;
_363    }
_363    tc.currentChannelContainer.removeClass('selected-channel').addClass('unselected-channel');
_363    channelElement.removeClass('unselected-channel').addClass('selected-channel');
_363    tc.currentChannelContainer = channelElement;
_363  }
_363
_363  function showAddChannelInput() {
_363    if (tc.messagingClient) {
_363      $newChannelInputRow.addClass('showing').removeClass('not-showing');
_363      $channelList.addClass('showing').removeClass('not-showing');
_363      $newChannelInput.focus();
_363    }
_363  }
_363
_363  function hideAddChannelInput() {
_363    $newChannelInputRow.addClass('not-showing').removeClass('showing');
_363    $channelList.addClass('not-showing').removeClass('showing');
_363    $newChannelInput.val('');
_363  }
_363
_363  function addChannel(channel) {
_363    if (channel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.generalChannel = channel;
_363    }
_363    var rowDiv = $('<div>').addClass('row channel-row');
_363    rowDiv.loadTemplate('#channel-template', {
_363      channelName: channel.friendlyName
_363    });
_363
_363    var channelP = rowDiv.children().children().first();
_363
_363    rowDiv.on('click', selectChannel);
_363    channelP.data('sid', channel.sid);
_363    if (tc.currentChannel && channel.sid === tc.currentChannel.sid) {
_363      tc.currentChannelContainer = channelP;
_363      channelP.addClass('selected-channel');
_363    }
_363    else {
_363      channelP.addClass('unselected-channel')
_363    }
_363
_363    $channelList.append(rowDiv);
_363  }
_363
_363  function deleteCurrentChannel() {
_363    if (!tc.currentChannel) {
_363      return;
_363    }
_363    if (tc.currentChannel.sid === tc.generalChannel.sid) {
_363      alert('You cannot delete the general channel');
_363      return;
_363    }
_363    tc.currentChannel.delete().then(function(channel) {
_363      console.log('channel: '+ channel.friendlyName + ' deleted');
_363      setupChannel(tc.generalChannel);
_363    });
_363  }
_363
_363  function selectChannel(event) {
_363    var target = $(event.target);
_363    var channelSid = target.data().sid;
_363    var selectedChannel = tc.channelArray.filter(function(channel) {
_363      return channel.sid === channelSid;
_363    })[0];
_363    if (selectedChannel === tc.currentChannel) {
_363      return;
_363    }
_363    setupChannel(selectedChannel);
_363  };
_363
_363  function disconnectClient() {
_363    leaveCurrentChannel();
_363    $channelList.text('');
_363    tc.$messageList.text('');
_363    channels = undefined;
_363    $statusRow.addClass('disconnected').removeClass('connected');
_363    tc.$messageList.addClass('disconnected').removeClass('connected');
_363    $connectPanel.addClass('disconnected').removeClass('connected');
_363    $inputText.removeClass('with-shadow');
_363    $typingRow.addClass('disconnected').removeClass('connected');
_363  }
_363
_363  tc.sortChannelsByName = function(channels) {
_363    return channels.sort(function(a, b) {
_363      if (a.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return -1;
_363      }
_363      if (b.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return 1;
_363      }
_363      return a.friendlyName.localeCompare(b.friendlyName);
_363    });
_363  };
_363
_363  return tc;
_363})();

We've actually got a real chat app going here, but let's make it more interesting with multiple channels.

Create a Channel

When a user clicks on the "+ Channel" link we'll show an input text field where it's possible to type the name of the new channel. Creating a channel is as simple as calling createChannel with an object that has the friendlyName key. You can create a channel with more options listed on the Channels section of the Programmable Chat documentation.

Create a Channel

src/main/webapp/js/twiliochat.js


_363var twiliochat = (function() {
_363  var tc = {};
_363
_363  var GENERAL_CHANNEL_UNIQUE_NAME = 'general';
_363  var GENERAL_CHANNEL_NAME = 'General Channel';
_363  var MESSAGES_HISTORY_LIMIT = 50;
_363
_363  var $channelList;
_363  var $inputText;
_363  var $usernameInput;
_363  var $statusRow;
_363  var $connectPanel;
_363  var $newChannelInputRow;
_363  var $newChannelInput;
_363  var $typingRow;
_363  var $typingPlaceholder;
_363
_363  $(document).ready(function() {
_363    tc.$messageList = $('#message-list');
_363    $channelList = $('#channel-list');
_363    $inputText = $('#input-text');
_363    $usernameInput = $('#username-input');
_363    $statusRow = $('#status-row');
_363    $connectPanel = $('#connect-panel');
_363    $newChannelInputRow = $('#new-channel-input-row');
_363    $newChannelInput = $('#new-channel-input');
_363    $typingRow = $('#typing-row');
_363    $typingPlaceholder = $('#typing-placeholder');
_363    $usernameInput.focus();
_363    $usernameInput.on('keypress', handleUsernameInputKeypress);
_363    $inputText.on('keypress', handleInputTextKeypress);
_363    $newChannelInput.on('keypress', tc.handleNewChannelInputKeypress);
_363    $('#connect-image').on('click', connectClientWithUsername);
_363    $('#add-channel-image').on('click', showAddChannelInput);
_363    $('#leave-span').on('click', disconnectClient);
_363    $('#delete-channel-span').on('click', deleteCurrentChannel);
_363  });
_363
_363  function handleUsernameInputKeypress(event) {
_363    if (event.keyCode === 13){
_363      connectClientWithUsername();
_363    }
_363  }
_363
_363  function handleInputTextKeypress(event) {
_363    if (event.keyCode === 13) {
_363      tc.currentChannel.sendMessage($(this).val());
_363      event.preventDefault();
_363      $(this).val('');
_363    }
_363    else {
_363      notifyTyping();
_363    }
_363  }
_363
_363  var notifyTyping = $.throttle(function() {
_363    tc.currentChannel.typing();
_363  }, 1000);
_363
_363  tc.handleNewChannelInputKeypress = function(event) {
_363    if (event.keyCode === 13) {
_363      tc.messagingClient.createChannel({
_363        friendlyName: $newChannelInput.val()
_363      }).then(hideAddChannelInput);
_363      $(this).val('');
_363      event.preventDefault();
_363    }
_363  };
_363
_363  function connectClientWithUsername() {
_363    var usernameText = $usernameInput.val();
_363    $usernameInput.val('');
_363    if (usernameText == '') {
_363      alert('Username cannot be empty');
_363      return;
_363    }
_363    tc.username = usernameText;
_363    fetchAccessToken(tc.username, connectMessagingClient);
_363  }
_363
_363  function fetchAccessToken(username, handler) {
_363    $.post('/twiliochat-servlets/token', {identity: username}, null, 'json')
_363      .done(function(response) {
_363        console.log('Successfully finished fetch of the Access Token.');
_363        handler(response.token);
_363      })
_363      .fail(function(error) {
_363        console.log('Failed to fetch the Access Token with error: ' + error);
_363      });
_363  }
_363
_363  function connectMessagingClient(token) {
_363    // Initialize the Chat messaging client
_363    tc.accessManager = new Twilio.AccessManager(token);
_363    Twilio.Chat.Client.create(token).then(function(client) {
_363      tc.messagingClient = client;
_363      updateConnectedUI();
_363      tc.loadChannelList(tc.joinGeneralChannel);
_363      tc.messagingClient.on('channelAdded', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('channelRemoved', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('tokenExpired', refreshToken);
_363    });
_363  }
_363
_363  function refreshToken() {
_363    fetchAccessToken(tc.username, setNewToken);
_363  }
_363
_363  function setNewToken(tokenResponse) {
_363    tc.accessManager.updateToken(tokenResponse.token);
_363  }
_363
_363  function updateConnectedUI() {
_363    $('#username-span').text(tc.username);
_363    $statusRow.addClass('connected').removeClass('disconnected');
_363    tc.$messageList.addClass('connected').removeClass('disconnected');
_363    $connectPanel.addClass('connected').removeClass('disconnected');
_363    $inputText.addClass('with-shadow');
_363    $typingRow.addClass('connected').removeClass('disconnected');
_363  }
_363
_363  tc.loadChannelList = function(handler) {
_363    if (tc.messagingClient === undefined) {
_363      console.log('Client is not initialized');
_363      return;
_363    }
_363
_363    tc.messagingClient.getPublicChannelDescriptors().then(function(channels) {
_363      tc.channelArray = tc.sortChannelsByName(channels.items);
_363      $channelList.text('');
_363      tc.channelArray.forEach(addChannel);
_363      if (typeof handler === 'function') {
_363        handler();
_363      }
_363    });
_363  };
_363
_363  tc.joinGeneralChannel = function() {
_363    console.log('Attempting to join "general" chat channel...');
_363    if (!tc.generalChannel) {
_363      // If it doesn't exist, let's create it
_363      tc.messagingClient.createChannel({
_363        uniqueName: GENERAL_CHANNEL_UNIQUE_NAME,
_363        friendlyName: GENERAL_CHANNEL_NAME
_363      }).then(function(channel) {
_363        console.log('Created general channel');
_363        tc.generalChannel = channel;
_363        tc.loadChannelList(tc.joinGeneralChannel);
_363      });
_363    }
_363    else {
_363      console.log('Found general channel:');
_363      setupChannel(tc.generalChannel);
_363    }
_363  };
_363
_363  function initChannel(channel) {
_363    console.log('Initialized channel ' + channel.friendlyName);
_363    return tc.messagingClient.getChannelBySid(channel.sid);
_363  }
_363
_363  function joinChannel(_channel) {
_363    return _channel.join()
_363      .then(function(joinedChannel) {
_363        console.log('Joined channel ' + joinedChannel.friendlyName);
_363        updateChannelUI(_channel);
_363        tc.currentChannel = _channel;
_363        tc.loadMessages();
_363        return joinedChannel;
_363      });
_363  }
_363
_363  function initChannelEvents() {
_363    console.log(tc.currentChannel.friendlyName + ' ready.');
_363    tc.currentChannel.on('messageAdded', tc.addMessageToList);
_363    tc.currentChannel.on('typingStarted', showTypingStarted);
_363    tc.currentChannel.on('typingEnded', hideTypingStarted);
_363    tc.currentChannel.on('memberJoined', notifyMemberJoined);
_363    tc.currentChannel.on('memberLeft', notifyMemberLeft);
_363    $inputText.prop('disabled', false).focus();
_363  }
_363
_363  function setupChannel(channel) {
_363    return leaveCurrentChannel()
_363      .then(function() {
_363        return initChannel(channel);
_363      })
_363      .then(function(_channel) {
_363        return joinChannel(_channel);
_363      })
_363      .then(initChannelEvents);
_363  }
_363
_363  tc.loadMessages = function() {
_363    tc.currentChannel.getMessages(MESSAGES_HISTORY_LIMIT)
_363      .then(function(messages) {
_363        messages.items.forEach(tc.addMessageToList);
_363    });
_363  };
_363
_363  function leaveCurrentChannel() {
_363    if (tc.currentChannel) {
_363      return tc.currentChannel.leave().then(function(leftChannel) {
_363        console.log('left ' + leftChannel.friendlyName);
_363        leftChannel.removeListener('messageAdded', tc.addMessageToList);
_363        leftChannel.removeListener('typingStarted', showTypingStarted);
_363        leftChannel.removeListener('typingEnded', hideTypingStarted);
_363        leftChannel.removeListener('memberJoined', notifyMemberJoined);
_363        leftChannel.removeListener('memberLeft', notifyMemberLeft);
_363      });
_363    } else {
_363      return Promise.resolve();
_363    }
_363  }
_363
_363  tc.addMessageToList = function(message) {
_363    var rowDiv = $('<div>').addClass('row no-margin');
_363    rowDiv.loadTemplate($('#message-template'), {
_363      username: message.author,
_363      date: dateFormatter.getTodayDate(message.dateCreated),
_363      body: message.body
_363    });
_363    if (message.author === tc.username) {
_363      rowDiv.addClass('own-message');
_363    }
_363
_363    tc.$messageList.append(rowDiv);
_363    scrollToMessageListBottom();
_363  };
_363
_363  function notifyMemberJoined(member) {
_363    notify(member.identity + ' joined the channel')
_363  }
_363
_363  function notifyMemberLeft(member) {
_363    notify(member.identity + ' left the channel');
_363  }
_363
_363  function notify(message) {
_363    var row = $('<div>').addClass('col-md-12');
_363    row.loadTemplate('#member-notification-template', {
_363      status: message
_363    });
_363    tc.$messageList.append(row);
_363    scrollToMessageListBottom();
_363  }
_363
_363  function showTypingStarted(member) {
_363    $typingPlaceholder.text(member.identity + ' is typing...');
_363  }
_363
_363  function hideTypingStarted(member) {
_363    $typingPlaceholder.text('');
_363  }
_363
_363  function scrollToMessageListBottom() {
_363    tc.$messageList.scrollTop(tc.$messageList[0].scrollHeight);
_363  }
_363
_363  function updateChannelUI(selectedChannel) {
_363    var channelElements = $('.channel-element').toArray();
_363    var channelElement = channelElements.filter(function(element) {
_363      return $(element).data().sid === selectedChannel.sid;
_363    });
_363    channelElement = $(channelElement);
_363    if (tc.currentChannelContainer === undefined && selectedChannel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.currentChannelContainer = channelElement;
_363    }
_363    tc.currentChannelContainer.removeClass('selected-channel').addClass('unselected-channel');
_363    channelElement.removeClass('unselected-channel').addClass('selected-channel');
_363    tc.currentChannelContainer = channelElement;
_363  }
_363
_363  function showAddChannelInput() {
_363    if (tc.messagingClient) {
_363      $newChannelInputRow.addClass('showing').removeClass('not-showing');
_363      $channelList.addClass('showing').removeClass('not-showing');
_363      $newChannelInput.focus();
_363    }
_363  }
_363
_363  function hideAddChannelInput() {
_363    $newChannelInputRow.addClass('not-showing').removeClass('showing');
_363    $channelList.addClass('not-showing').removeClass('showing');
_363    $newChannelInput.val('');
_363  }
_363
_363  function addChannel(channel) {
_363    if (channel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.generalChannel = channel;
_363    }
_363    var rowDiv = $('<div>').addClass('row channel-row');
_363    rowDiv.loadTemplate('#channel-template', {
_363      channelName: channel.friendlyName
_363    });
_363
_363    var channelP = rowDiv.children().children().first();
_363
_363    rowDiv.on('click', selectChannel);
_363    channelP.data('sid', channel.sid);
_363    if (tc.currentChannel && channel.sid === tc.currentChannel.sid) {
_363      tc.currentChannelContainer = channelP;
_363      channelP.addClass('selected-channel');
_363    }
_363    else {
_363      channelP.addClass('unselected-channel')
_363    }
_363
_363    $channelList.append(rowDiv);
_363  }
_363
_363  function deleteCurrentChannel() {
_363    if (!tc.currentChannel) {
_363      return;
_363    }
_363    if (tc.currentChannel.sid === tc.generalChannel.sid) {
_363      alert('You cannot delete the general channel');
_363      return;
_363    }
_363    tc.currentChannel.delete().then(function(channel) {
_363      console.log('channel: '+ channel.friendlyName + ' deleted');
_363      setupChannel(tc.generalChannel);
_363    });
_363  }
_363
_363  function selectChannel(event) {
_363    var target = $(event.target);
_363    var channelSid = target.data().sid;
_363    var selectedChannel = tc.channelArray.filter(function(channel) {
_363      return channel.sid === channelSid;
_363    })[0];
_363    if (selectedChannel === tc.currentChannel) {
_363      return;
_363    }
_363    setupChannel(selectedChannel);
_363  };
_363
_363  function disconnectClient() {
_363    leaveCurrentChannel();
_363    $channelList.text('');
_363    tc.$messageList.text('');
_363    channels = undefined;
_363    $statusRow.addClass('disconnected').removeClass('connected');
_363    tc.$messageList.addClass('disconnected').removeClass('connected');
_363    $connectPanel.addClass('disconnected').removeClass('connected');
_363    $inputText.removeClass('with-shadow');
_363    $typingRow.addClass('disconnected').removeClass('connected');
_363  }
_363
_363  tc.sortChannelsByName = function(channels) {
_363    return channels.sort(function(a, b) {
_363      if (a.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return -1;
_363      }
_363      if (b.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return 1;
_363      }
_363      return a.friendlyName.localeCompare(b.friendlyName);
_363    });
_363  };
_363
_363  return tc;
_363})();

Next, we will see how we can switch between channels.

Join Other Channels

When you tap on the name of a channel from the sidebar, that channel is set as the selectedChannel. The selectChannel method takes care of joining to the selected channel and setting up the selectedChannel.

Join Other Channels

src/main/webapp/js/twiliochat.js


_363var twiliochat = (function() {
_363  var tc = {};
_363
_363  var GENERAL_CHANNEL_UNIQUE_NAME = 'general';
_363  var GENERAL_CHANNEL_NAME = 'General Channel';
_363  var MESSAGES_HISTORY_LIMIT = 50;
_363
_363  var $channelList;
_363  var $inputText;
_363  var $usernameInput;
_363  var $statusRow;
_363  var $connectPanel;
_363  var $newChannelInputRow;
_363  var $newChannelInput;
_363  var $typingRow;
_363  var $typingPlaceholder;
_363
_363  $(document).ready(function() {
_363    tc.$messageList = $('#message-list');
_363    $channelList = $('#channel-list');
_363    $inputText = $('#input-text');
_363    $usernameInput = $('#username-input');
_363    $statusRow = $('#status-row');
_363    $connectPanel = $('#connect-panel');
_363    $newChannelInputRow = $('#new-channel-input-row');
_363    $newChannelInput = $('#new-channel-input');
_363    $typingRow = $('#typing-row');
_363    $typingPlaceholder = $('#typing-placeholder');
_363    $usernameInput.focus();
_363    $usernameInput.on('keypress', handleUsernameInputKeypress);
_363    $inputText.on('keypress', handleInputTextKeypress);
_363    $newChannelInput.on('keypress', tc.handleNewChannelInputKeypress);
_363    $('#connect-image').on('click', connectClientWithUsername);
_363    $('#add-channel-image').on('click', showAddChannelInput);
_363    $('#leave-span').on('click', disconnectClient);
_363    $('#delete-channel-span').on('click', deleteCurrentChannel);
_363  });
_363
_363  function handleUsernameInputKeypress(event) {
_363    if (event.keyCode === 13){
_363      connectClientWithUsername();
_363    }
_363  }
_363
_363  function handleInputTextKeypress(event) {
_363    if (event.keyCode === 13) {
_363      tc.currentChannel.sendMessage($(this).val());
_363      event.preventDefault();
_363      $(this).val('');
_363    }
_363    else {
_363      notifyTyping();
_363    }
_363  }
_363
_363  var notifyTyping = $.throttle(function() {
_363    tc.currentChannel.typing();
_363  }, 1000);
_363
_363  tc.handleNewChannelInputKeypress = function(event) {
_363    if (event.keyCode === 13) {
_363      tc.messagingClient.createChannel({
_363        friendlyName: $newChannelInput.val()
_363      }).then(hideAddChannelInput);
_363      $(this).val('');
_363      event.preventDefault();
_363    }
_363  };
_363
_363  function connectClientWithUsername() {
_363    var usernameText = $usernameInput.val();
_363    $usernameInput.val('');
_363    if (usernameText == '') {
_363      alert('Username cannot be empty');
_363      return;
_363    }
_363    tc.username = usernameText;
_363    fetchAccessToken(tc.username, connectMessagingClient);
_363  }
_363
_363  function fetchAccessToken(username, handler) {
_363    $.post('/twiliochat-servlets/token', {identity: username}, null, 'json')
_363      .done(function(response) {
_363        console.log('Successfully finished fetch of the Access Token.');
_363        handler(response.token);
_363      })
_363      .fail(function(error) {
_363        console.log('Failed to fetch the Access Token with error: ' + error);
_363      });
_363  }
_363
_363  function connectMessagingClient(token) {
_363    // Initialize the Chat messaging client
_363    tc.accessManager = new Twilio.AccessManager(token);
_363    Twilio.Chat.Client.create(token).then(function(client) {
_363      tc.messagingClient = client;
_363      updateConnectedUI();
_363      tc.loadChannelList(tc.joinGeneralChannel);
_363      tc.messagingClient.on('channelAdded', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('channelRemoved', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('tokenExpired', refreshToken);
_363    });
_363  }
_363
_363  function refreshToken() {
_363    fetchAccessToken(tc.username, setNewToken);
_363  }
_363
_363  function setNewToken(tokenResponse) {
_363    tc.accessManager.updateToken(tokenResponse.token);
_363  }
_363
_363  function updateConnectedUI() {
_363    $('#username-span').text(tc.username);
_363    $statusRow.addClass('connected').removeClass('disconnected');
_363    tc.$messageList.addClass('connected').removeClass('disconnected');
_363    $connectPanel.addClass('connected').removeClass('disconnected');
_363    $inputText.addClass('with-shadow');
_363    $typingRow.addClass('connected').removeClass('disconnected');
_363  }
_363
_363  tc.loadChannelList = function(handler) {
_363    if (tc.messagingClient === undefined) {
_363      console.log('Client is not initialized');
_363      return;
_363    }
_363
_363    tc.messagingClient.getPublicChannelDescriptors().then(function(channels) {
_363      tc.channelArray = tc.sortChannelsByName(channels.items);
_363      $channelList.text('');
_363      tc.channelArray.forEach(addChannel);
_363      if (typeof handler === 'function') {
_363        handler();
_363      }
_363    });
_363  };
_363
_363  tc.joinGeneralChannel = function() {
_363    console.log('Attempting to join "general" chat channel...');
_363    if (!tc.generalChannel) {
_363      // If it doesn't exist, let's create it
_363      tc.messagingClient.createChannel({
_363        uniqueName: GENERAL_CHANNEL_UNIQUE_NAME,
_363        friendlyName: GENERAL_CHANNEL_NAME
_363      }).then(function(channel) {
_363        console.log('Created general channel');
_363        tc.generalChannel = channel;
_363        tc.loadChannelList(tc.joinGeneralChannel);
_363      });
_363    }
_363    else {
_363      console.log('Found general channel:');
_363      setupChannel(tc.generalChannel);
_363    }
_363  };
_363
_363  function initChannel(channel) {
_363    console.log('Initialized channel ' + channel.friendlyName);
_363    return tc.messagingClient.getChannelBySid(channel.sid);
_363  }
_363
_363  function joinChannel(_channel) {
_363    return _channel.join()
_363      .then(function(joinedChannel) {
_363        console.log('Joined channel ' + joinedChannel.friendlyName);
_363        updateChannelUI(_channel);
_363        tc.currentChannel = _channel;
_363        tc.loadMessages();
_363        return joinedChannel;
_363      });
_363  }
_363
_363  function initChannelEvents() {
_363    console.log(tc.currentChannel.friendlyName + ' ready.');
_363    tc.currentChannel.on('messageAdded', tc.addMessageToList);
_363    tc.currentChannel.on('typingStarted', showTypingStarted);
_363    tc.currentChannel.on('typingEnded', hideTypingStarted);
_363    tc.currentChannel.on('memberJoined', notifyMemberJoined);
_363    tc.currentChannel.on('memberLeft', notifyMemberLeft);
_363    $inputText.prop('disabled', false).focus();
_363  }
_363
_363  function setupChannel(channel) {
_363    return leaveCurrentChannel()
_363      .then(function() {
_363        return initChannel(channel);
_363      })
_363      .then(function(_channel) {
_363        return joinChannel(_channel);
_363      })
_363      .then(initChannelEvents);
_363  }
_363
_363  tc.loadMessages = function() {
_363    tc.currentChannel.getMessages(MESSAGES_HISTORY_LIMIT)
_363      .then(function(messages) {
_363        messages.items.forEach(tc.addMessageToList);
_363    });
_363  };
_363
_363  function leaveCurrentChannel() {
_363    if (tc.currentChannel) {
_363      return tc.currentChannel.leave().then(function(leftChannel) {
_363        console.log('left ' + leftChannel.friendlyName);
_363        leftChannel.removeListener('messageAdded', tc.addMessageToList);
_363        leftChannel.removeListener('typingStarted', showTypingStarted);
_363        leftChannel.removeListener('typingEnded', hideTypingStarted);
_363        leftChannel.removeListener('memberJoined', notifyMemberJoined);
_363        leftChannel.removeListener('memberLeft', notifyMemberLeft);
_363      });
_363    } else {
_363      return Promise.resolve();
_363    }
_363  }
_363
_363  tc.addMessageToList = function(message) {
_363    var rowDiv = $('<div>').addClass('row no-margin');
_363    rowDiv.loadTemplate($('#message-template'), {
_363      username: message.author,
_363      date: dateFormatter.getTodayDate(message.dateCreated),
_363      body: message.body
_363    });
_363    if (message.author === tc.username) {
_363      rowDiv.addClass('own-message');
_363    }
_363
_363    tc.$messageList.append(rowDiv);
_363    scrollToMessageListBottom();
_363  };
_363
_363  function notifyMemberJoined(member) {
_363    notify(member.identity + ' joined the channel')
_363  }
_363
_363  function notifyMemberLeft(member) {
_363    notify(member.identity + ' left the channel');
_363  }
_363
_363  function notify(message) {
_363    var row = $('<div>').addClass('col-md-12');
_363    row.loadTemplate('#member-notification-template', {
_363      status: message
_363    });
_363    tc.$messageList.append(row);
_363    scrollToMessageListBottom();
_363  }
_363
_363  function showTypingStarted(member) {
_363    $typingPlaceholder.text(member.identity + ' is typing...');
_363  }
_363
_363  function hideTypingStarted(member) {
_363    $typingPlaceholder.text('');
_363  }
_363
_363  function scrollToMessageListBottom() {
_363    tc.$messageList.scrollTop(tc.$messageList[0].scrollHeight);
_363  }
_363
_363  function updateChannelUI(selectedChannel) {
_363    var channelElements = $('.channel-element').toArray();
_363    var channelElement = channelElements.filter(function(element) {
_363      return $(element).data().sid === selectedChannel.sid;
_363    });
_363    channelElement = $(channelElement);
_363    if (tc.currentChannelContainer === undefined && selectedChannel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.currentChannelContainer = channelElement;
_363    }
_363    tc.currentChannelContainer.removeClass('selected-channel').addClass('unselected-channel');
_363    channelElement.removeClass('unselected-channel').addClass('selected-channel');
_363    tc.currentChannelContainer = channelElement;
_363  }
_363
_363  function showAddChannelInput() {
_363    if (tc.messagingClient) {
_363      $newChannelInputRow.addClass('showing').removeClass('not-showing');
_363      $channelList.addClass('showing').removeClass('not-showing');
_363      $newChannelInput.focus();
_363    }
_363  }
_363
_363  function hideAddChannelInput() {
_363    $newChannelInputRow.addClass('not-showing').removeClass('showing');
_363    $channelList.addClass('not-showing').removeClass('showing');
_363    $newChannelInput.val('');
_363  }
_363
_363  function addChannel(channel) {
_363    if (channel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.generalChannel = channel;
_363    }
_363    var rowDiv = $('<div>').addClass('row channel-row');
_363    rowDiv.loadTemplate('#channel-template', {
_363      channelName: channel.friendlyName
_363    });
_363
_363    var channelP = rowDiv.children().children().first();
_363
_363    rowDiv.on('click', selectChannel);
_363    channelP.data('sid', channel.sid);
_363    if (tc.currentChannel && channel.sid === tc.currentChannel.sid) {
_363      tc.currentChannelContainer = channelP;
_363      channelP.addClass('selected-channel');
_363    }
_363    else {
_363      channelP.addClass('unselected-channel')
_363    }
_363
_363    $channelList.append(rowDiv);
_363  }
_363
_363  function deleteCurrentChannel() {
_363    if (!tc.currentChannel) {
_363      return;
_363    }
_363    if (tc.currentChannel.sid === tc.generalChannel.sid) {
_363      alert('You cannot delete the general channel');
_363      return;
_363    }
_363    tc.currentChannel.delete().then(function(channel) {
_363      console.log('channel: '+ channel.friendlyName + ' deleted');
_363      setupChannel(tc.generalChannel);
_363    });
_363  }
_363
_363  function selectChannel(event) {
_363    var target = $(event.target);
_363    var channelSid = target.data().sid;
_363    var selectedChannel = tc.channelArray.filter(function(channel) {
_363      return channel.sid === channelSid;
_363    })[0];
_363    if (selectedChannel === tc.currentChannel) {
_363      return;
_363    }
_363    setupChannel(selectedChannel);
_363  };
_363
_363  function disconnectClient() {
_363    leaveCurrentChannel();
_363    $channelList.text('');
_363    tc.$messageList.text('');
_363    channels = undefined;
_363    $statusRow.addClass('disconnected').removeClass('connected');
_363    tc.$messageList.addClass('disconnected').removeClass('connected');
_363    $connectPanel.addClass('disconnected').removeClass('connected');
_363    $inputText.removeClass('with-shadow');
_363    $typingRow.addClass('disconnected').removeClass('connected');
_363  }
_363
_363  tc.sortChannelsByName = function(channels) {
_363    return channels.sort(function(a, b) {
_363      if (a.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return -1;
_363      }
_363      if (b.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return 1;
_363      }
_363      return a.friendlyName.localeCompare(b.friendlyName);
_363    });
_363  };
_363
_363  return tc;
_363})();

At some point, your users will want to delete a channel. Let's have a look at how that can be done.

Delete a Channel

Deleting a channel is even more simple than creating one. The application lets the user delete the channel they are currently joining through the "delete current channel" link. The only thing you need to do to actually delete the channel from Twilio is call the delete method on the channel you are trying to delete. Like other methods on the Channel object, it'll return a promise where you can set the success handler.

Delete a Channel

src/main/webapp/js/twiliochat.js


_363var twiliochat = (function() {
_363  var tc = {};
_363
_363  var GENERAL_CHANNEL_UNIQUE_NAME = 'general';
_363  var GENERAL_CHANNEL_NAME = 'General Channel';
_363  var MESSAGES_HISTORY_LIMIT = 50;
_363
_363  var $channelList;
_363  var $inputText;
_363  var $usernameInput;
_363  var $statusRow;
_363  var $connectPanel;
_363  var $newChannelInputRow;
_363  var $newChannelInput;
_363  var $typingRow;
_363  var $typingPlaceholder;
_363
_363  $(document).ready(function() {
_363    tc.$messageList = $('#message-list');
_363    $channelList = $('#channel-list');
_363    $inputText = $('#input-text');
_363    $usernameInput = $('#username-input');
_363    $statusRow = $('#status-row');
_363    $connectPanel = $('#connect-panel');
_363    $newChannelInputRow = $('#new-channel-input-row');
_363    $newChannelInput = $('#new-channel-input');
_363    $typingRow = $('#typing-row');
_363    $typingPlaceholder = $('#typing-placeholder');
_363    $usernameInput.focus();
_363    $usernameInput.on('keypress', handleUsernameInputKeypress);
_363    $inputText.on('keypress', handleInputTextKeypress);
_363    $newChannelInput.on('keypress', tc.handleNewChannelInputKeypress);
_363    $('#connect-image').on('click', connectClientWithUsername);
_363    $('#add-channel-image').on('click', showAddChannelInput);
_363    $('#leave-span').on('click', disconnectClient);
_363    $('#delete-channel-span').on('click', deleteCurrentChannel);
_363  });
_363
_363  function handleUsernameInputKeypress(event) {
_363    if (event.keyCode === 13){
_363      connectClientWithUsername();
_363    }
_363  }
_363
_363  function handleInputTextKeypress(event) {
_363    if (event.keyCode === 13) {
_363      tc.currentChannel.sendMessage($(this).val());
_363      event.preventDefault();
_363      $(this).val('');
_363    }
_363    else {
_363      notifyTyping();
_363    }
_363  }
_363
_363  var notifyTyping = $.throttle(function() {
_363    tc.currentChannel.typing();
_363  }, 1000);
_363
_363  tc.handleNewChannelInputKeypress = function(event) {
_363    if (event.keyCode === 13) {
_363      tc.messagingClient.createChannel({
_363        friendlyName: $newChannelInput.val()
_363      }).then(hideAddChannelInput);
_363      $(this).val('');
_363      event.preventDefault();
_363    }
_363  };
_363
_363  function connectClientWithUsername() {
_363    var usernameText = $usernameInput.val();
_363    $usernameInput.val('');
_363    if (usernameText == '') {
_363      alert('Username cannot be empty');
_363      return;
_363    }
_363    tc.username = usernameText;
_363    fetchAccessToken(tc.username, connectMessagingClient);
_363  }
_363
_363  function fetchAccessToken(username, handler) {
_363    $.post('/twiliochat-servlets/token', {identity: username}, null, 'json')
_363      .done(function(response) {
_363        console.log('Successfully finished fetch of the Access Token.');
_363        handler(response.token);
_363      })
_363      .fail(function(error) {
_363        console.log('Failed to fetch the Access Token with error: ' + error);
_363      });
_363  }
_363
_363  function connectMessagingClient(token) {
_363    // Initialize the Chat messaging client
_363    tc.accessManager = new Twilio.AccessManager(token);
_363    Twilio.Chat.Client.create(token).then(function(client) {
_363      tc.messagingClient = client;
_363      updateConnectedUI();
_363      tc.loadChannelList(tc.joinGeneralChannel);
_363      tc.messagingClient.on('channelAdded', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('channelRemoved', $.throttle(tc.loadChannelList));
_363      tc.messagingClient.on('tokenExpired', refreshToken);
_363    });
_363  }
_363
_363  function refreshToken() {
_363    fetchAccessToken(tc.username, setNewToken);
_363  }
_363
_363  function setNewToken(tokenResponse) {
_363    tc.accessManager.updateToken(tokenResponse.token);
_363  }
_363
_363  function updateConnectedUI() {
_363    $('#username-span').text(tc.username);
_363    $statusRow.addClass('connected').removeClass('disconnected');
_363    tc.$messageList.addClass('connected').removeClass('disconnected');
_363    $connectPanel.addClass('connected').removeClass('disconnected');
_363    $inputText.addClass('with-shadow');
_363    $typingRow.addClass('connected').removeClass('disconnected');
_363  }
_363
_363  tc.loadChannelList = function(handler) {
_363    if (tc.messagingClient === undefined) {
_363      console.log('Client is not initialized');
_363      return;
_363    }
_363
_363    tc.messagingClient.getPublicChannelDescriptors().then(function(channels) {
_363      tc.channelArray = tc.sortChannelsByName(channels.items);
_363      $channelList.text('');
_363      tc.channelArray.forEach(addChannel);
_363      if (typeof handler === 'function') {
_363        handler();
_363      }
_363    });
_363  };
_363
_363  tc.joinGeneralChannel = function() {
_363    console.log('Attempting to join "general" chat channel...');
_363    if (!tc.generalChannel) {
_363      // If it doesn't exist, let's create it
_363      tc.messagingClient.createChannel({
_363        uniqueName: GENERAL_CHANNEL_UNIQUE_NAME,
_363        friendlyName: GENERAL_CHANNEL_NAME
_363      }).then(function(channel) {
_363        console.log('Created general channel');
_363        tc.generalChannel = channel;
_363        tc.loadChannelList(tc.joinGeneralChannel);
_363      });
_363    }
_363    else {
_363      console.log('Found general channel:');
_363      setupChannel(tc.generalChannel);
_363    }
_363  };
_363
_363  function initChannel(channel) {
_363    console.log('Initialized channel ' + channel.friendlyName);
_363    return tc.messagingClient.getChannelBySid(channel.sid);
_363  }
_363
_363  function joinChannel(_channel) {
_363    return _channel.join()
_363      .then(function(joinedChannel) {
_363        console.log('Joined channel ' + joinedChannel.friendlyName);
_363        updateChannelUI(_channel);
_363        tc.currentChannel = _channel;
_363        tc.loadMessages();
_363        return joinedChannel;
_363      });
_363  }
_363
_363  function initChannelEvents() {
_363    console.log(tc.currentChannel.friendlyName + ' ready.');
_363    tc.currentChannel.on('messageAdded', tc.addMessageToList);
_363    tc.currentChannel.on('typingStarted', showTypingStarted);
_363    tc.currentChannel.on('typingEnded', hideTypingStarted);
_363    tc.currentChannel.on('memberJoined', notifyMemberJoined);
_363    tc.currentChannel.on('memberLeft', notifyMemberLeft);
_363    $inputText.prop('disabled', false).focus();
_363  }
_363
_363  function setupChannel(channel) {
_363    return leaveCurrentChannel()
_363      .then(function() {
_363        return initChannel(channel);
_363      })
_363      .then(function(_channel) {
_363        return joinChannel(_channel);
_363      })
_363      .then(initChannelEvents);
_363  }
_363
_363  tc.loadMessages = function() {
_363    tc.currentChannel.getMessages(MESSAGES_HISTORY_LIMIT)
_363      .then(function(messages) {
_363        messages.items.forEach(tc.addMessageToList);
_363    });
_363  };
_363
_363  function leaveCurrentChannel() {
_363    if (tc.currentChannel) {
_363      return tc.currentChannel.leave().then(function(leftChannel) {
_363        console.log('left ' + leftChannel.friendlyName);
_363        leftChannel.removeListener('messageAdded', tc.addMessageToList);
_363        leftChannel.removeListener('typingStarted', showTypingStarted);
_363        leftChannel.removeListener('typingEnded', hideTypingStarted);
_363        leftChannel.removeListener('memberJoined', notifyMemberJoined);
_363        leftChannel.removeListener('memberLeft', notifyMemberLeft);
_363      });
_363    } else {
_363      return Promise.resolve();
_363    }
_363  }
_363
_363  tc.addMessageToList = function(message) {
_363    var rowDiv = $('<div>').addClass('row no-margin');
_363    rowDiv.loadTemplate($('#message-template'), {
_363      username: message.author,
_363      date: dateFormatter.getTodayDate(message.dateCreated),
_363      body: message.body
_363    });
_363    if (message.author === tc.username) {
_363      rowDiv.addClass('own-message');
_363    }
_363
_363    tc.$messageList.append(rowDiv);
_363    scrollToMessageListBottom();
_363  };
_363
_363  function notifyMemberJoined(member) {
_363    notify(member.identity + ' joined the channel')
_363  }
_363
_363  function notifyMemberLeft(member) {
_363    notify(member.identity + ' left the channel');
_363  }
_363
_363  function notify(message) {
_363    var row = $('<div>').addClass('col-md-12');
_363    row.loadTemplate('#member-notification-template', {
_363      status: message
_363    });
_363    tc.$messageList.append(row);
_363    scrollToMessageListBottom();
_363  }
_363
_363  function showTypingStarted(member) {
_363    $typingPlaceholder.text(member.identity + ' is typing...');
_363  }
_363
_363  function hideTypingStarted(member) {
_363    $typingPlaceholder.text('');
_363  }
_363
_363  function scrollToMessageListBottom() {
_363    tc.$messageList.scrollTop(tc.$messageList[0].scrollHeight);
_363  }
_363
_363  function updateChannelUI(selectedChannel) {
_363    var channelElements = $('.channel-element').toArray();
_363    var channelElement = channelElements.filter(function(element) {
_363      return $(element).data().sid === selectedChannel.sid;
_363    });
_363    channelElement = $(channelElement);
_363    if (tc.currentChannelContainer === undefined && selectedChannel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.currentChannelContainer = channelElement;
_363    }
_363    tc.currentChannelContainer.removeClass('selected-channel').addClass('unselected-channel');
_363    channelElement.removeClass('unselected-channel').addClass('selected-channel');
_363    tc.currentChannelContainer = channelElement;
_363  }
_363
_363  function showAddChannelInput() {
_363    if (tc.messagingClient) {
_363      $newChannelInputRow.addClass('showing').removeClass('not-showing');
_363      $channelList.addClass('showing').removeClass('not-showing');
_363      $newChannelInput.focus();
_363    }
_363  }
_363
_363  function hideAddChannelInput() {
_363    $newChannelInputRow.addClass('not-showing').removeClass('showing');
_363    $channelList.addClass('not-showing').removeClass('showing');
_363    $newChannelInput.val('');
_363  }
_363
_363  function addChannel(channel) {
_363    if (channel.uniqueName === GENERAL_CHANNEL_UNIQUE_NAME) {
_363      tc.generalChannel = channel;
_363    }
_363    var rowDiv = $('<div>').addClass('row channel-row');
_363    rowDiv.loadTemplate('#channel-template', {
_363      channelName: channel.friendlyName
_363    });
_363
_363    var channelP = rowDiv.children().children().first();
_363
_363    rowDiv.on('click', selectChannel);
_363    channelP.data('sid', channel.sid);
_363    if (tc.currentChannel && channel.sid === tc.currentChannel.sid) {
_363      tc.currentChannelContainer = channelP;
_363      channelP.addClass('selected-channel');
_363    }
_363    else {
_363      channelP.addClass('unselected-channel')
_363    }
_363
_363    $channelList.append(rowDiv);
_363  }
_363
_363  function deleteCurrentChannel() {
_363    if (!tc.currentChannel) {
_363      return;
_363    }
_363    if (tc.currentChannel.sid === tc.generalChannel.sid) {
_363      alert('You cannot delete the general channel');
_363      return;
_363    }
_363    tc.currentChannel.delete().then(function(channel) {
_363      console.log('channel: '+ channel.friendlyName + ' deleted');
_363      setupChannel(tc.generalChannel);
_363    });
_363  }
_363
_363  function selectChannel(event) {
_363    var target = $(event.target);
_363    var channelSid = target.data().sid;
_363    var selectedChannel = tc.channelArray.filter(function(channel) {
_363      return channel.sid === channelSid;
_363    })[0];
_363    if (selectedChannel === tc.currentChannel) {
_363      return;
_363    }
_363    setupChannel(selectedChannel);
_363  };
_363
_363  function disconnectClient() {
_363    leaveCurrentChannel();
_363    $channelList.text('');
_363    tc.$messageList.text('');
_363    channels = undefined;
_363    $statusRow.addClass('disconnected').removeClass('connected');
_363    tc.$messageList.addClass('disconnected').removeClass('connected');
_363    $connectPanel.addClass('disconnected').removeClass('connected');
_363    $inputText.removeClass('with-shadow');
_363    $typingRow.addClass('disconnected').removeClass('connected');
_363  }
_363
_363  tc.sortChannelsByName = function(channels) {
_363    return channels.sort(function(a, b) {
_363      if (a.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return -1;
_363      }
_363      if (b.friendlyName === GENERAL_CHANNEL_NAME) {
_363        return 1;
_363      }
_363      return a.friendlyName.localeCompare(b.friendlyName);
_363    });
_363  };
_363
_363  return tc;
_363})();

That's it! We've just implemented a simple chat application for Java using the Servlet API.

Where to Next?

If you are a Java developer working with Twilio, you might want to check out these other tutorials:

SMS and MMS Notifications

Never miss another server outage. Learn how to build a server notification system that will alert all administrators via SMS when a server outage occurs.

Workflow Automation

Increase your rate of response by automating the workflows that are key to your business. In this tutorial, learn how to build a ready-for-scale automated SMS workflow, for a vacation rental company.

Masked Phone Numbers

Protect your users' privacy by anonymously connecting them with Twilio Voice and SMS. Learn how to create disposable phone numbers on-demand, so two users can communicate without exchanging personal information.

Did this help?

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