bitcoin-s/docs/wallet/wallet-callbacks.md

---
title: Wallet Callbacks
id: wallet-callbacks
---

#### Wallet Callbacks

Bitcoin-S support call backs for the following events that happen in the wallet:

1. onTransactionProcessed
2. onTransactionBroadcast
3. onReservedUtxos
4. onNewAddressGenerated
5. onBlockProcessed

That means every time one of these events happens, we will call your callback
so that you can be notified of the event. These callbacks will be run after the message has been
recieved and will execute synchronously. If any of them fail an error log will be output, and the remainder of the callbacks will continue.
Let's make an easy one:

#### DLC Wallet callbacks
Bitcoin-s support callbacks for the following events in the DLC wallet: 
1. onStateChange

That means everytime a DLC's state changes, your callback will be executed so
that you are notified of the event. For instance, if your DLC transitions from
`Offered` -> `Accepted`, your callback will be executed.

#### Example

Here is an example of constructing a wallet and registering a callback, so you can be notified of an event.

```scala mdoc:invisible
import akka.actor.ActorSystem
import org.bitcoins.crypto._
import org.bitcoins.core.protocol.transaction.Transaction
import org.bitcoins.core.wallet.fee._
import org.bitcoins.feeprovider._
import org.bitcoins.rpc.client.v19.BitcoindV19RpcClient
import org.bitcoins.rpc.config.BitcoindInstanceLocal
import org.bitcoins.testkit.BitcoinSTestAppConfig
import org.bitcoins.wallet._
import org.bitcoins.wallet.config.WalletAppConfig
import scala.concurrent.{ExecutionContextExecutor, Future}
```

```scala mdoc:compile-only

implicit val system: ActorSystem = ActorSystem("example")
implicit val ec: ExecutionContextExecutor = system.dispatcher
implicit val walletConf: WalletAppConfig =
    BitcoinSTestAppConfig.getNeutrinoTestConfig().walletConf

// let's use a helper method to get a v19 bitcoind
// and a ChainApi

val bitcoind = BitcoindV19RpcClient(BitcoindInstanceLocal.fromConfFile())
val aesPasswordOpt = Some(AesPassword.fromString("password"))

// Here is a super simple example of a callback, this could be replaced with anything, from
// relaying the transaction on the network, finding relevant wallet outputs, verifying the transaction,
// or writing it to disk
val exampleProcessTx: OnTransactionProcessed = (tx: Transaction) =>
    Future.successful(println(s"Processed Tx: ${tx.txIdBE}"))

// Create our WalletCallbacks that
val exampleCallbacks = WalletCallbacks(
    onTransactionProcessed = Vector(exampleProcessTx))

// Now we can create a wallet
val wallet =
    Wallet(
           nodeApi = bitcoind,
           chainQueryApi = bitcoind,
           feeRateApi = ConstantFeeRateProvider(SatoshisPerVirtualByte.one))

// Finally, we can add the callbacks to our wallet config
walletConf.addCallbacks(exampleCallbacks)

// Then to trigger the event we can run
val exampleTx = Transaction(
    "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")
wallet.processTransaction(exampleTx, None)

```