Building a Group Chat with Wazo

18 November 2022

2022 Hackathon

Every year, Wazo organizes a hackathon in the region of Quebec with all the members of the engineering team. For us, the hackathon is a great way to do some team building and meet in real life, since not everyone lives around Quebec City.

banner cottage huard (small) front view cottage (small) rear view cottage lake (small)


One subject for the hackathon was to build a chat app powered by Wazo supporting: GIFs, emojis, reactions on messages, files attachment and Markdown. Also behind the scene, we wanted to build a bridge between Wazo And Matrix to explore methods for integrating Wazo with third-party platforms.

Jesse, Charles, Francois and I (Francis) teamed up to explore these ideas further.

Working on Wazo-Platform to Support Group Chat and Reactions

Support Multiple Recipients

Firstly, we needed to remove the hard limit of two members per room. This part was the easiest since it’s a hardcoded condition set by us. However, several questions would need to be addressed to make it production ready:

  • How do we handle message history visibility when a new member is added to a conversation
  • How to define max participants
  • How to leave a conversation
  • etc…

Adding Reactions to Messages

We added a new table chatd_room_message_reaction. This table will be in charge of storing all reactions added by a user to a message. Users can add as many emojis as they wants to a message, but not the same twice.

class RoomMessageReaction(Base):

    __tablename__ = 'chatd_room_message_reaction'

    message_uuid = Column(
        ForeignKey('chatd_room_message.uuid', ondelete='CASCADE'),

    user_uuid = Column(UUIDType(), nullable=False, primary_key=True)

    emoji = Column(String(10))

    created_at = Column(
        server_default=text("(now() at time zone 'utc')"),

The second part, is to add real-time reactions in the chat, so we created two new events for this :

  • chatd_users_room_message_reaction_created
  • chatd_users_room_message_reaction_deleted

These events look like this and allow the app to add/remove the reactions to a specific message in real-time.

  "message_uuid": "a0e7dc92-92a3-485b-b8dd-09a909a1f5a0",
  "data": {
    "emoji": "🎉",
    "user_uuid": "8040ec9d-1a61-4ca3-abe5-ad7c2f192e03"

Funny corner-case

At first, we added a limit of 1 character for the emoji column. But we figured out that some emojis are more than one character. This is how variations for an emoji are handled ❤️🧡💛💚💙💜🤎🖤🤍.

Building a UI Powered by Wazo Platform

banner cottage huard (small) front view cottage (small) rear view cottage lake (small)

For the UI part, we used the SolidJS reactive library and our SDK wazo-js-sdk. Building the UI was quite straightforward since our SDK handled token creation and allowed us to use the preconfigured WebSocket Client.

Live Chat Logic

A Group Chat is mainly HTTP Requests and WebSocket listeners. Here’s the HTTP Request that we need to make in the app:

import getApiClient from '@wazo/sdk/lib/service/getApiClient';

const client = getApiClient('hostname.example');

// On page load, we fetch rooms for the current user
const rooms = await client.chatd.getUserRooms();

// On room load, we fetch previous message in a room
const messages = await client.chatd.getRoomMessages(ROOM_UUID);

// On form submit, we send the new message to chatd services
await client.chatd.sendRoomMessage(ROOM_UUID, {
  content: 'The new message content',
  alias: 'Alias/Name of the member',

The second part is about listening to WebSocket messages. We used the wazo-js-sdk WebSocket client. Here are the events that we listened to :

// Initialize websocket client
import { WazoWebSocketClient } from '@wazo/sdk';

const ws = new WazoWebSocketClient({
  token: response.token,
  events: [
    // Other events to listen
  version: '2',

// Main events to listen
ws.on('chatd_user_room_message_created', (message) => {
  // Listen for "room message created" events
  // - Validate the message is in the displayed room
  // - Add message to all messages
  // Message Payload Example:
  // {
  //   room_uuid: "697a35a6-534c-461d-9466-6f77d0181e80",
  //   data: {
  //     content: 'The new message content',
  //     alias: 'Alias/Name of the member',
  //     created_at: '2022-10-24T15:50:00.000000+00:00',
  //     user_uuid: '8040ec9d-1a61-4ca3-abe5-ad7c2f192e03',
  //     uuid: 'a0e7dc92-92a3-485b-b8dd-09a909a1f5a0',
  //   }
  // }

ws.on('chatd_user_room_created', (message) => {
  // Listen for "room created" events
  // - Add new room to the listing
  // Message Payload Example
  // {
  //   uuid: '6f9c7df4-8529-4336-9b65-21ceec774583'
  //   name: 'New Room Name',
  //   tenant_uuid: '47e1a830-cb3a-4ac9-9117-82acbb54d72b',
  //   users: [
  //     {
  //       tenant_uuid: '5d5e7e18-46ae-4046-beda-3cdcd5449142',
  //       uuid: '551d06a1-808a-417d-995d-7abb66d55c33',
  //     },
  //     // Other users
  //   ]
  // }

The Hardest Parts of a Group Chat Application

We found that the most challenging parts of a group chat application are :

  • Creating a feature-rich interface. We may have not realized it at first, but chat apps are powerful tools with a lot of shortcuts. For example: editing previous messages, switching to new channels, aliases in messages (@mention, emoji syntax :smile:, link detection, etc.).
  • More complex features and settings are common as well: threads, notifications, participant management, privacy settings, etc.


The hackathon was a great opportunity for us to work closely with our colleagues and try new technologies. It also gives us a good idea about what is missing and how much effort would be required to implement and deploy these features

Code reference: show me the code

All our code created during the hackathon is open-source. Dive in and ask us questions on our public Mattermost.

Community Supported

Wazo Platform is supported by its community. Use our various channels to reach out.


Video @ Kamailio World: Dangerous Demos

Video @ the Telecom Application Development Summit: What can you do with Wazo?

Video @ the Telecom Application Development Summit: WAZO Keynote: xCPaaS

Get Connected, Contribute & Build value!

Designed with by Xiaoying Riley for developersCopyright 2016-2023 The Wazo Authors (see the AUTHORS file)