Permissions & Moderation

In many types of calls, there is a requirement for providing different users with certain permissions and capabilities. A typical example is a webinar where the host wants to control who can speak or who can share their video or screen.

The Stream Video SDK provides a certain set of permissions and capabilities that can be used to control the behavior of participants in a call.

Conceptual overview

Roles

The Stream Video API allows assigning roles to users. Each user has a global role, and they will also have a call-level role for each call they join. The Stream Video API provides a set of predefined roles, but it’s also possible to create your own roles.

Call types

Call types also allow for a more granular control system:

you can enable/disable certain features on a call type level
you can configure how each call-level role works on a call type level

Capabilities

Based on a user’s roles and the call type settings, we can determine which actions are allowed for a user joined to a specific call.

Permissions

As soon as you join a call, the Call instance would allow you to check the permissions of the local user or perform some permission-related actions:

Check permissions

import { OwnCapability } from '@stream-io/video-client';

const call = client.call(type, id);
const canSendAudio = call.permissionsContext.hasPermission(
  OwnCapability.SEND_AUDIO,
);

Request permissions

Every user may request permission to perform certain actions depending on the call type and call settings. For example, in an audio-room call type, only the hosts have send-audio permission by default. Other users should request this permission before they can start sending audio if the call settings allow it.

import { OwnCapability } from '@stream-io/video-client';

const call = client.call(type, id);
if (!call.permissionsContext.canRequest(OwnCapability.SEND_AUDIO)) {
  console.log('The host has disabled the ability to request this permission');
  return;
}
await call.requestPermissions({
  permissions: [OwnCapability.SEND_AUDIO],
});

Approving permission requests

Call hosts and moderators can approve permission requests from other users. Whenever a user requests a certain permission, a call.permission_request event will be emitted on the Call instance. You can listen to this event and approve the request.

import {
  PermissionRequestEvent,
  StreamCallEvent,
} from '@stream-io/video-client';

const call = client.call(type, id);
call.on('call.permission_request', async (event: StreamCallEvent) => {
  const request = event as PermissionRequestEvent;
  if (shouldApproveRequest(request)) {
    await call.grantPermissions(request.user.id, request.permissions);
  }
});

Moderation

At any time, a moderator or host can decide to either grant or revoke certain permission to any participant.

import { OwnCapability } from '@stream-io/video-client';

const call = client.call(type, id);
await call.updateUserPermissions({
  user_id: 'demo-user',
  grant_permission: [OwnCapability.SEND_AUDIO, OwnCapability.SEND_VIDEO],
  revoke_permissions: [OwnCapability.SCREENSHARE],
});

// alternate API for granting user permissions:
await call.grantPermissions('demo-user', [
  OwnCapability.SEND_AUDIO,
  OwnCapability.SEND_VIDEO,
]);

// alternate API for revoking user permissions:
await call.revokePermissions('demo-user', [OwnCapability.SCREENSHARE]);

The end user would get notified via a WebSocket event with a type: call.permissions_updated. In the case of revoked permissions, the client would automatically stop publishing the appropriate tracks.

Muting participants

In addition to granting or revoking permissions, a moderator or host can also mute a participant. This is a common scenario as quite often, participants may be a source of unwanted noise or distraction.

const call = client.call(type, id);
await call.muteUser('demo-user-id', 'audio');
await call.muteUser('demo-user-id', 'video');
await call.muteUser('demo-user-id', 'screenshare');

// or, mute in bulk
await call.muteUser(['demo-user-id', 'demo-user-id-2'], 'audio');

// or, muting self
await call.muteSelf('audio');

// or, muting others
await call.muteOthers('audio');

// or, mute all, including self.
await call.muteAllUsers('audio');

This operation doesn’t revoke any permission, and the user would still be able to un-mute itself.

Ending call for everyone

In some cases, a moderator or host may want to end the call for everyone.

const call = client.call(type, id);
await call.endCall();

This operation will emit call.ended event to every participant in the call. The client would automatically stop publishing any tracks and leave the call.

Ended calls can’t be re-joined.

Capabilities

Every user connecting to a Stream Call has a set of Capabilities. The capabilities of the local user live in the state of the Call instance.

const call = client.call(type, id);
const { ownCapabilities } = call.state;

// or if you want to subscribe to changes:
call.state.ownCapabilities$.subscribe((capabilities) => {
  // do something with the capabilities
});

Capabilities will have the type OwnCapability.

Querying Call Members

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