> For the complete documentation index, see [llms.txt](https://developer.barchart.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.barchart.com/getting-started/service-types.md).

# Streaming Service Types

When subscribing to market data streams, choose the service level that fits your application.

For example, applications that need updates every 30 seconds can request `REAL_TIME_SNAPSHOT`. Set the snapshot interval with the subscription request.

Review [User Settings](/openfeed-api/user-settings.md) to confirm your available exchanges and service permissions.

### Realtime

The `REAL_TIME` service type streams data as it happens on the exchange. If you are not permissioned for real-time data, Openfeed Streaming downgrades the service to `DELAYED` or rejects the `SubscriptionRequest`.

#### Subscription response example

```protobuf
Sending: subscriptionRequest {
  token: "fe39068e-08fb-43ac-a786-bec6aa42de95"
  service: REAL_TIME
  requests {
    symbol: "^BTCUSD"
    subscriptionType: TRADES
  }
}

...

subscriptionResponse {
  status {
    result: SUCCESS
    service: DELAYED
  }
  symbol: "^BTCUSD"
  marketId: 2616696889477124894
  channelId: 30
  subscriptionType: TRADES
}
```

#### Rejected subscription response example

```protobuf
subscriptionResponse {
  status {
    result: INSUFFICIENT_PRIVILEGES
    message: "Not authorized"
  }
  symbol: "^BTCUSD"
  subscriptionType: DEPTH_PRICE
}
```

### Delayed

The `DELAYED` service type streams data delayed by exchange requirements. Delays vary by exchange, but are generally 10 to 15 minutes behind the real-time market.

Message formats and server behavior remain the same as real-time service.

For control over the update interval, use a [Streaming Snapshot Type](/getting-started/streaming-snapshot-types.md).


---

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