# Eventhub Subscriber

The **EventHub Subscriber** component is designed to consume event data from **Azure Event Hubs**. It creates an **event processor client** that reads and processes event data from EventHub partitions.

This component supports two authentication methods for connecting to EventHub:

* **Connection String**
* **Principal Secret**

It is typically used to ingest real-time streaming event data into pipelines for processing, analytics, or storage.

### Configuration Sections

All component configurations are classified into the following sections:

* **Basic Information**
* **Meta Information**
* **Resource Configuration**

### Basic Information Tab

The *Basic Information* tab defines general execution settings.

| Field                       | Description                                                   | Required |
| --------------------------- | ------------------------------------------------------------- | -------- |
| **Invocation Type**         | Select execution mode: **Batch** or **Real-Time**.            | Yes      |
| **Deployment Type**         | Displays the deployment type of the component (pre-selected). | Yes      |
| **Container Image Version** | Displays the Docker image version used (pre-selected).        | Yes      |
| **Failover Event**          | Select a failover event for error handling.                   | Optional |
| **Batch Size**              | Maximum number of events processed per cycle (minimum: 10).   | Yes      |

### Meta Information Tab

The *Meta Information* tab defines connection details for consuming events from **Azure EventHub**. The configuration differs depending on the chosen authentication method.

#### **Method 1: Read Using Connection String**

| Field                    | Description                                                                             | Required |
| ------------------------ | --------------------------------------------------------------------------------------- | -------- |
| **Connection String**    | Full connection string with parameters to establish a connection to EventHub.           | Yes      |
| **Consumer Group**       | Logical grouping of event consumers that read from the same partition.                  | Yes      |
| **EventHub Name**        | Name of the specific EventHub within the namespace.                                     | Yes      |
| **Checkpoint Location**  | Stores the position in the stream representing the last successfully processed event.   | Yes      |
| **Enqueued Time**        | Timestamp when the event was added to the partition (time of occurrence or generation). | Optional |
| **Subscriber Namespace** | Logical entity for grouping subscribers and managing access within EventHub namespace.  | Yes      |

#### **Method 2: Read Using Principal Secret**

| Field                    | Description                                                                            | Required |
| ------------------------ | -------------------------------------------------------------------------------------- | -------- |
| **Client ID**            | Azure AD application ID registered in Azure portal.                                    | Yes      |
| **Tenant ID**            | ID of the Azure AD tenant that contains the application/service principal.             | Yes      |
| **Client Secret**        | Secret value associated with the Azure AD application for authentication.              | Yes      |
| **Consumer Group**       | Logical grouping of event consumers that read from the same partition.                 | Yes      |
| **EventHub Name**        | Name of the EventHub within the namespace.                                             | Yes      |
| **Checkpoint Location**  | Stores the position in the stream representing the last successfully processed event.  | Yes      |
| **Enqueued Time**        | Timestamp when the event was added to the partition.                                   | Optional |
| **Subscriber Namespace** | Logical entity for grouping subscribers and managing access within EventHub namespace. | Yes      |

### Saving the Configuration

1. Configure either **Connection String** or **Principal Secret** parameters.
2. Click the **Save Component** (Storage icon).
3. A notification confirms successful configuration.
4. Once activated, the EventHub Subscriber begins consuming events from the specified EventHub.

### Example Workflow

1. Configure EventHub Subscriber with **Connection String** authentication.
   * EventHub Name: `iot-events`
   * Consumer Group: `cg-iot-subscribers`
   * Checkpoint Location: `checkpoint/iot-sensor-events`
2. Start the pipeline.
3. Incoming IoT sensor events are read from EventHub and forwarded to downstream analytics components for real-time monitoring.


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