# Handling messages

At some point you'll want to handle messages that have been sent to your application. This can be done by creating a handler and registering it with the [BusConfiguration](/reference/busconfiguration.md).

The following example creates a handler for a hotel booking application 

Declare a command that models the **ReserveRoom** command

```typescript
// reserve-room.ts

import { Command } from '@node-ts/bus-messages'

export class ReserveRoom extends Command {
  $name = 'reservations/reserve-room'
  $version = 0
  
  constructor (
    readonly roomId: string,
    readonly bookingId: string
  ) {
    super()
  }
}
```

Create a handler that receives a command to `ReserveRoom` that it delegates the operation to a `reservationService`. 

{% hint style="info" %}
Handlers should be kept as dumb as possible and delegate the work to dedicated services. This will help keep the messaging concerns of your application decoupled from the actual work it needs to do.
{% endhint %}

```typescript
// reserve-room-handler.ts

import { handlerFor } from '@node-ts/bus-core'
import { ReserveRoom } from '../messages'
import { reservationService } from '../services'

export const reserveRoomHandler = handlerFor(
  ReserveRoom,
  command => reservationService.reserveRoom(command.reservation, command.bookingId)
)
```

Register the handler with the BusConfiguration.

```typescript
// application.ts

import { Bus, BusInstance } from '@node-ts/bus-core'
import { reserveRoomHandler } from './handlers'
import { ReserveRoom } from './messages'

let bus: BusInstance
const start = async () => {
  bus = await Bus.configure()
    .withHandler(reserveRoomHandler)
    .initialize()
    
  // Start the bus to commence processing messages
  await bus.start()
}

start
  .then(async () => bus.send(new ReserveRoom(
    '63a65cf0-d239-4b83-96da-f33f013db23a',
    '12b85a56-e929-47a8-9ac3-e87739d5d215'
  ))
  .catch(console.error)
```


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