Tracking room events with Webhooks

With Webhooks you can set up user-defined callbacks triggered by meeting events. These are a great way to programmatically keep track of some of the events and actions happening around your meetings.

Configuration

Webhooks are managed from the "Configure" section of your account, so they need to be set up by an admin in your organization.

Visit the "Configure" section of your Whereby Embedded account dashboard and scroll down to find the Webhooks setup.

At the moment the following event types are supported:

• room.client.joined - this is sent when a user joins the meeting room

• room.client.left - this is sent when a user leaves the meeting room (this could be via the leave button or by closing the browser tab)

• room.client.knocked- this is sent when a visitor knocks the meeting room from the waiting room

• room.client.knockCancelled- this is sent when a visitor cancels their knock from the waiting room (this could be via the cancel button or a result of network issues)

• room.session.started: Sent when a room session starts, which is when there are at least 2 users in a room.

• room.session.ended: Sent when a room session ends. Currently, a session will end when the number of participants has been less than 2 for some time. This heuristic could change in the future to better determine that a session has ended.

• transcription.finished: Sent when a transcription has finished processing.

• transcription.failed: Sent when a transcription has failed to process.

• recording.finished: Sent when a cloud recording has finished and the recording has uploaded successfully.

Event objects

Events are delivered to their corresponding webhook endpoint in JSON format, as the body of an HTTP request. The table below describes their top-level attributes.

Property	Description
id	String that uniquely identifies the event.
apiVersion	The Whereby API version used to populate data. Refer to the details on Versioning for how webhook data may change.
createdAt	ISO representation of the creation date of the event.
type	The event’s type identifier, e.g. room.client.joined
data	Object containing information associated with the event.

In-Room Data properties

Please note that in-room webhook events are sent for interactions that happen between the creation of the room and an hour after the endDate of a room. Also consider that a particular event can be sent more than once, and that you could receive events in non-chronological order.

Properties in data that are common to all in-room webhook events:

Property	Description
meetingId	The identifier of the meeting that the user has joined/left or where the session has started/ended.
roomName	The string that identifies the room assigned to the meeting. It’s the last path parameter of the roomUrl.

Additional properties in data for room.client.joined , room.client.left room.client.knocked and room.client.knockCancelled:

Property	Description
displayName	The visible name displayed to others in the meeting.
roomSessionId	The roomSessionId for the meeting.
participantId	The current user's participantId. Can be used for insights data.
metadata	String that matches the "metadata" query parameter passed to the room URL.
externalId	String that matches the "externalId" query parameter passed to the room URL.

Additional properties in data for just room.client.joined and room.client.left:

Property	Description
roleName	The client’s role depending on what URL they use to access the meeting.
numClients	Number of clients connected to the meeting after the event.
numClientsByRoleName	Number of clients connected to the meeting after the event, grouped by the roleName.

The property roleName will have one of the following values:

• owner: A user with an admin account in your Embedded organization.

• member: A user with an account in your Embedded organization.

• host: A user joined using the hostRoomUrl.

• visitor: A user joined using the regular roomUrl.

• granted_visitor: The roleName that is assigned to a Participant after they have knocked and been let in by a Host.

• viewer: A user joined using the viewerRoomUrl.

• granted_viewer: The roleName that is assigned to a Participant if they are queued before a Host joins.

• recorder: A cloud recording instance has started or stopped.

• streamer: A streaming instance has started or stopped.

An example of a webhook event object:

JSON

{
  "id": "d7c4df48b85318352b47d2df45872bf9be87595af379e2a8ad8f1ad28b2a482e",
  "apiVersion": "1.0",
  "createdAt": "2021-01-21T16:29:59.681Z",
  "type": "room.client.joined",
  "data": {
    "roleName": "host",
    "displayName": "Joe Bloggs",
    "meetingId": "134",
    "roomName": "/af0b7b66-c738-4981-887a-ad416754f32d",
    "numClients": 8,
    "numClientsByRoleName": {
      "host": 1,
      "visitor": 7
    },
    "metadata": "<custom-metadata>",
    "externalId": "<custom-id>"
  }
}

Transcription Data properties

Properties in data that are common to all transcription webhook events:

Property	Description
transcriptionId	The identifier of the transcription that has finished processing or failed to process.

Additional properties in data for just transcription.finished:

Property	Description
recordingId	The identifier of the recording that the transcription is associated with.
durationInSeconds	The duration of the recording in seconds.

Additional properties in data for just transcription.failed:

Property	Description
error	The error message that describes why the transcription failed to process.

Cloud Recording Data properties

Properties in data for the recording.finished webhook event:

Property	Description
filename	The name and extension of the recording.
recordingId	The identifier of the recording.
roomName	The string that identifies the room assigned to the meeting.
status	The final status of the recording. It can be only completed for now.

Validating events

To prevent from man-in-the-middle attacks ↗ , webhook requests to your endpoint contain a signature in the Whereby-Signature header. This string is generated with a unique secret that only you can view when creating or editing a webhook in the Embedded dashboard. Only Whereby and you have access to this secret, and no third party can send forged events to your endpoint. On top of that the header also includes a timestamp to help you prevent replay attacks. The header is composed of a timestamp and the signature itself, for example:

Text

Whereby-Signature:
t=1606227791,v1=94a23dc9d73e8e6abdf9d4095aee954697e9317e9649e742361b35707edd45a3

To verify an event’s signature, follow these steps:

1. Extract the timestamp and signature by splitting the string on , then removing both t= and v1= from the resulting strings.

2. Prepare the signedPayload string by concatenating the timestamp (as a string), the character . and the JSON event object (the request body).

3. Calculate the HMAC: It is the SHA256 hash of signedPayload, using the endpoint’s signing secret (the one you get when creating the webhook) as the key.

4. Compare the signature from the header to the one you just generated. To protect yourself from timing attacks consider using a constant-time equality function instead of the default equality operator of the language you’re using. Finally, to prevent replay attacks, compare the header’s timestamp with the current one and decide if the elapsed time is within your allowed threshold.

An example of a webhook event validation:

Node

import crypto from "crypto";

const WEBHOOK_SECRET = "<WEBHOOK_SECRET>";
const MAX_ELAPSED_TIME = 1000 * 60; // 1 minutes in milliseconds

function isWebhookEventValid({ body, headers }) {
  const wbSignature = headers["whereby-signature"];
  const matches = wbSignature.matchAll(/t=(.*),v1=(.*)/gm);

  let timestamp, signature;
  for (const match of matches) {
    timestamp = match[1];
    signature = match[2];
  }

  const current = new Date();
  const diffTime = current - parseInt(timestamp * 1000, 10);

  const signedPayload = timestamp + "." + JSON.stringify(body);

  const sha256Hasher = crypto.createHmac("sha256", WEBHOOK_SECRET);
  const hash = sha256Hasher.update(signedPayload);
  const hashStr = hash.digest("hex");

  return (
    crypto.timingSafeEqual(
      Buffer.from(hashStr, "utf-8"),
      Buffer.from(signature, "utf-8")
    ) && diffTime < Whereby.MAX_ELAPSED_TIME
  );
}

Failed delivery

Any 5xx response to the webhook delivery request will trigger a retry, for a total of 2 retries. A short exponential backoff will be used. We also have a 5 seconds timeout on webhook requests, if the response takes longer than that the same retry mechanism will be used.