# Working with streams

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Each RTMS stream follows a predictable flow that starts with at least one session being started; continues while your app connects to the required servers, receives stream data, and maintains connection; and ends when the stream ends. A stream can have multiple sessions happening within it, each session typically corresponds to an individual user.

Sessions can exist in the following states:

| State      |                                                                                   |
| ---------- | --------------------------------------------------------------------------------- |
| INACTIVE   | Default state. The session is not active yet.                                     |
| INITIALIZE | The session is initializing.                                                      |
| STARTED    | The session has started.                                                          |
| PAUSED     | The session has been paused either by the user or the host.                       |
| RESUMED    | The paused session has been resumed.                                              |
| STOPPED    | The session is being stopped by the user, host, or the meeting or webinar ending. |

## Prerequisites

To process RTMS data, you need to add RTMS features to your app. Your app needs the appropriate event subscriptions, scopes, and, optionally, the JavaScript SDK or REST APIs for starting and managing sessions. For more information, see [Add RTMS features to your app](/docs/rtms/meetings/add-features/).

Once your app is configured, RTMS sessions will follow these steps:

## Step 1: RTMS is started

RTMS provides role-based controls to manage the streaming experience. You can set their apps to auto-start streams when the user joins a meeting, or webinar, or to start manually by using the REST API or JavaScript SDK.

In addition, the streaming experience is also controlled by:

-   Admins can manage the auto-start settings for users, groups, or the entire account in the Zoom web portal.

-   Hosts can set RTMS start permissions for each meeting or webinar.

-   Participants can manually start, pause, and end their own streams. (Requires host approval.)

Auto-start is enabled at the account, group, or user level and automatically launches RTMS when a user with auto-start enabled:

-   **Hosts** - RTMS starts automatically when the user initiates a meeting or webinar.
-   **Joins as participant** - RTMS starts automatically when the user joins a meeting or webinar.

If the user is a guest rather than a host, the host can decide to:

-   Allow RTMS to start without host approval.
-   Require host approval to start RTMS.
-   Disallow RTMS from starting automatically.

Enable users to manually start streams in meetings and webinars using RTMS button controls. For more information, see
[Add JS SDK APIs for apps](/docs/rtms/meetings/add-features/#optional-add-js-sdk-apis-for-in-meeting-apps).

You can use JavaScript (JS) SDK method calls to programmatically start RTMS streams in live meetings and webinars on a Zoom Surface App. This can be used either as the `onclick`
event of a button, or when your RTMS-enabled app is opened during a meeting or webinar.

Manual start triggers:

**Method**: `startRTMS()`

### Example

```javascript
import zoomSdk from "@zoom/appssdk";

(async () => {
    try {
        const configResponse = await zoomSdk.config({
            capabilities: ["startRTMS"],
        });

        const { runningContext } = configResponse;
        if (runningContext === "inMeeting") {
            const rtmsResponse = await zoomSdk.callZoomApi("startRTMS");
            console.debug("RTMS Start Response:", rtmsResponse);
        }
    } catch (e) {
        console.error("Zoom SDK Error:", e);
    }
})();
```

Apps can initiate a stream in a meeting or webinar with a REST API request.

This enables backend or external systems to start an RTMS session without Zoom client user interaction. For example, RTMS could be started from your company's scheduling software rather than from the meeting or webinar.

**Endpoint**: Send API requests to [Update participant Realtime Media Streams (RTMS) app status](/docs/api/meetings/#tag/meetings/patch/live_meetings/{meetingId}/rtms_app/status)
**Authentication**: Use a valid Zoom access token. Payloads must be securely signed.

> The host or designated alternate host must be present. The API doesn't support in-meeting, or in-webinar, host change.

## Step 2: App receives streaming notification

Zoom sends [`meeting.rtms_started`](/docs/api/rtms/events/#tag/meeting/postmeeting.rtms_started), or [`webinar.rtms_started`](/docs/api/rtms/events/#tag/webinar/postwebinar.rtms_started), webhook events when RTMS streaming starts. You can then use the information in the event to establish a signaling connection in the next step.

To receive notifications when new streams are available, create an HTTP POST handler in your web app. This handler acts as the endpoint for incoming webhook events.
In your app settings, provide the URL of this endpoint.

After you receive an event, [verify the event's signature](/docs/api/webhooks/#verify-webhook-events) to ensure it's from a trusted source.

## Step 3: App establishes signaling connection

Establishing a signal connection to an RTMS server enables your app to establish and manage a WebSocket connection with the RTMS server. It begins with a signed handshake and includes messages for session readiness, state updates, and stream control.

The signal connection provides lifecycle updates for the media connection, such as when it starts, stops, or encounters an event.

When you have the connection details and know a stream is available, you can start the connection to the signaling server.

1. Run the following command to create a signature that your app will use to securely connect to the RTMS server; replacing `client_id` and `secret` with your app's **Client ID** and **Client Secret**, and `meeting_uuid` and `rtms_stream_id` with the **meeting_uuid**, or **webinar_id**, and **rtms_stream_id** from the streaming notification event.

    ```javascript
    HMACSHA256(client_id + "," + meeting_uuid + "," + rtms_stream_id, secret);
    ```

1. Your app sends a [signaling handshake request](/docs/rtms/event-reference/#signaling-handshake-request) with the `meeting_uuid`, or `webinar_uuid`, and `rtms_stream_id` from the streaming notification event and the signature you just created. If the handshake is successful, your app will receive a [signaling handshake response](/docs/rtms/event-reference/#signaling-handshake-response) confirming the connection and containing the media server locations.

    > If the handshake fails, the server responds with a `SIGNALING_HAND_SHAKE_RESP` message containing a status code and reason.

1. (Optional) Your app can [Subscribe to events](/docs/rtms/event-reference/#subscribe-to-events) for participant changes and active speaker updates.

Once your app has successfully established a signaling connection, it can now establish a media connection.

## Step 4: App establishes the media connection

Use one of the URLs list in `media_server.server_urls` in the [signaling handshake response](/docs/rtms/event-reference/#signaling-handshake-response)
to establish a media WebSocket connection.

> **Use integers for message and event types**
>
> For [data type](/docs/rtms/data-types/) definitions, use the representative enum integers.
>
> Example: Send `msg_type: 1` ✓ not `msg_type: SIGNALING_HAND_SHAKE_REQ` ✗

1. Your app sends a [media handshake request](/docs/rtms/event-reference/#media-handshake-request) with the `meeting_uuid`, or `webinar_uuid`, and `rtms_stream_id` from the streaming notification and the signature you created in [Step 3](/docs/rtms/meetings/work-with-streams/#step-3-app-establishes-signaling-connection) above. If the handshake is successful, your app will receive a [media handshake response](/docs/rtms/event-reference/#media-handshake-response) confirming the connection and containing information about the available media.

    > If the handshake fails, the server responds with a `SIGNALING_HAND_SHAKE_RESP` message containing a status code and reason.

1. Your app sends a [client ready ACK message](/docs/rtms/event-reference/#client-ready-ack-message) to the RTMS server media connection to indicate readiness to receive media.

Now that the connection is made, your app can receive media data.

## Step 5: App receives media data

Once the connection is established, your app receives continuous streams of:

-   [Audio data](/docs/rtms/event-reference/#audio-data) from participants
-   [Video data](/docs/rtms/event-reference/#video-data) from active speakers or a specific individual
-   [Transcript data](/docs/rtms/event-reference/#transcript-data) from spoken audio
-   [In-meeting events](/docs/rtms/event-reference/#active-speaker-change) for participant changes and active speaker updates

By default, video streams the active speaker. To stream a specific participant's video instead, see [Stream a single participant's video](/docs/rtms/meetings/video-single-stream/).

For more information about working with media data, see [Handling media data](/docs/rtms/meetings/media/).

## Step 6: App maintains connections

Throughout the session, your app must:

-   Respond to [keep-alive requests](/docs/rtms/event-reference/#keep-alive-request) to maintain stable connections (sent every 10 seconds when no data is flowing)
-   Monitor [session state updates](/docs/rtms/event-reference/#session-state-updated) for pauses, resumes, or interruptions
-   Handle [stream state changes](/docs/rtms/event-reference/#stream-state-updated) for connection issues or termination

> **Connection maintenance is critical:** If your app fails to respond to three consecutive keep-alive requests (sent every 10 seconds during idle periods), the RTMS server will terminate the connection.

If a connection has been interrupted, see [Failover and reconnection](/docs/rtms/meetings/failover-reconnection/) for more information on reestablishing the connection.

## Step 7: Stream ends

The RTMS stream ends when:

-   The meeting or webinar concludes
-   The user manually stops streaming
-   The host disables RTMS
-   Connection issues cause termination
-   App users leave the meeting or webinar

Your app receives a [`meeting.rtms_stopped`](/docs/api/rtms/events/#tag/meeting/postmeeting.rtms_stopped), or [`webinar.rtms_stopped`](/docs/api/rtms/events/#tag/webinar/postwebinar.rtms_stopped), notification indicating the stream has ended.