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# Servers

> Configure server URLs and protocols to help users connect to your event-driven API.

AsyncAPI allows you to specify one or more server configurations under the `servers` key.

**`asyncapi.yml`**

```yml asyncapi.yml 

servers: 
  production:
    host: api.yourcompany.com
    protocol: wss
    description: Production WebSocket server
  staging:
    host: staging.api.yourcompany.com
    protocol: wss
    description: Staging WebSocket server
```

Specifying servers is valuable for both SDKs and Docs:

* For SDKs, your users won't need to manually specify the server URL at client instantiation
* For Docs, your API playground will automatically connect to the correct server

## Protocol support

AsyncAPI supports various protocols for event-driven communication:

**`asyncapi.yml`**

```yml asyncapi.yml {4,8,12}
servers: 
  websocket-server:
    host: ws.api.yourcompany.com
    protocol: ws
    description: WebSocket server for real-time communication
  mqtt-server:
    host: mqtt.yourcompany.com
    protocol: mqtt
    description: MQTT broker for IoT devices
  kafka-server:
    host: kafka.yourcompany.com
    protocol: kafka
    description: Kafka cluster for event streaming
```

## Naming your servers

We recommend giving your servers descriptive names to make it clear what each server is for:

**`asyncapi.yml`**

```yml asyncapi.yml 
servers: 
  production:
    host: api.yourcompany.com
    protocol: wss
    description: Production WebSocket server
  staging:
    host: staging.api.yourcompany.com
    protocol: wss
    description: Staging environment for testing
  development:
    host: localhost:8080
    protocol: ws
    description: Local development server
```

## Server variables

You can use variables in your server configurations to make them more flexible:

**`asyncapi.yml`**

```yml asyncapi.yml {3-10}
servers:
  production:
    host: '{environment}.api.yourcompany.com'
    protocol: wss
    variables:
      environment:
        default: prod
        enum:
          - prod
          - staging
        description: Environment name
```

## Multiple protocols for different channels

If you have different channels that use different protocols, you can specify this in your server configuration:

**`asyncapi.yml`**

```yml asyncapi.yml {2-14, 17-21}
servers:
  websocket-server:
    host: ws.api.yourcompany.com
    protocol: wss
    description: WebSocket server for real-time notifications
  mqtt-server:
    host: mqtt.api.yourcompany.com
    protocol: mqtt
    description: MQTT broker for IoT device communication
  kafka-server:
    host: kafka.api.yourcompany.com
    protocol: kafka
    description: Kafka for high-throughput event streaming

channels:
  user/notifications:
    servers:
      - websocket-server
    address: user/notifications
    description: Real-time user notifications via WebSocket
  device/telemetry:
    servers:
      - mqtt-server
    address: device/telemetry
    description: IoT device telemetry via MQTT
```

This allows different channels to use the most appropriate protocol for their use case.

> Define server URLs and protocols to help users connect to your event-driven API.