Blockchain Providers

The Provider trait is Scalus’s abstraction for interacting with the Cardano blockchain. Providers allow you to send transactions and query blockchain state in a consistent way, regardless of whether you’re working with a real blockchain, test node, or local emulator.

Overview

The Provider interface provides methods for:

Querying UTxOs by address, datum, or tokens
Submitting CBOR-encoded transactions
Retrieving transaction information
Accessing blockchain state

Available Providers

Emulator

The Emulator implements the Provider trait but operates entirely locally, without any network connection. It provides:

In-memory UTxO set management
Local transaction validation using ledger rules
Instant feedback without network delays
Perfect isolation for testing

The Emulator is ideal for:

Unit test suites
Rapid development iterations
Scenarios where launching a local node would be inconvenient

Learn more about the Emulator in the Emulator documentation.

BlockfrostProvider

BlockfrostProvider connects to the Cardano blockchain via the Blockfrost API service. This provider is useful for:

Verifying transactions and scripts against a real blockchain
Testing against a test node (testnet, preview, preprod)
Production deployments

Interacting with Blockfrost incurs network delays, making it less suitable for rapid development cycles or unit tests.

Example Usage

Here’s how you might use different providers interchangeably:


// Using Blockfrost for production
val blockfrostProvider = BlockfrostProvider(apiKey, network)
 
// Using Emulator for testing
val emulatorProvider = Emulator(
  Map(
    input(0) -> adaOutput(Alice.address, 100)
  )
)
 
// Same code works with both providers
def buildAndSubmit(provider: Provider) = {
  val tx = TxBuilder(testEnv)
    .payTo(Bob.address, Value.ada(10))
    .complete(provider, Alice.address)
    .await()
    .transaction
 
  provider.submit(tx).await()
}
 
// Works with Blockfrost
buildAndSubmit(blockfrostProvider)
 
// Works with Emulator
buildAndSubmit(emulatorProvider)

Provider Methods

The Provider trait defines methods for interacting with the blockchain. Common methods include:

findUtxo(txIn: TxIn): Find a specific UTxO by transaction input
findUtxos(address: Address): Find all UTxOs at an address
submit(tx: Transaction): Submit a transaction for processing
And more query methods for specific use cases

Check the API documentation for the complete list of available methods.