Ethers uses a middleware-based architecture. You start the middleware stack with
a [`Provider`](ethers_providers::Provider), and wrap it with additional
middleware functionalities that you need.
## Available Middleware
- [`Signer`](./signer/struct.SignerMiddleware.html): Signs transactions locally,
with a private key or a hardware wallet
- [`Nonce Manager`](./nonce_manager/struct.NonceManagerMiddleware.html): Manages
nonces locally, allowing the rapid broadcast of transactions without having to
wait for them to be submitted
- [`Gas Escalator`](./gas_escalator/struct.GasEscalatorMiddleware.html): Bumps
transaction gas prices in the background
- [`Gas Oracle`](./gas_oracle/struct.GasOracleMiddleware.html): Allows getting
your gas price estimates from places other than `eth_gasPrice`.
- [`Transformer`](./transformer/trait.Transformer.html): Allows intercepting and
transforming a transaction to be broadcasted via a proxy wallet, e.g.
[`DSProxy`](./transformer/struct.DsProxy.html).
## Example of a middleware stack
```no_run
use ethers_providers::{Provider, Http};
use ethers_signers::{LocalWallet, Signer};
use ethers_middleware::{
gas_escalator::{GasEscalatorMiddleware, GeometricGasPrice, Frequency},
gas_oracle::{GasOracleMiddleware, EthGasStation, GasCategory},
signer::SignerMiddleware,
nonce_manager::NonceManagerMiddleware,
};
use ethers_core::rand;
use std::convert::TryFrom;
// Start the stack
let provider = Provider::<Http>::try_from("http://localhost:8545").unwrap();
// Escalate gas prices
let escalator = GeometricGasPrice::new(1.125, 60u64, None::<u64>);
let provider =
GasEscalatorMiddleware::new(provider, escalator, Frequency::PerBlock);
// Sign transactions with a private key
let signer = LocalWallet::new(&mut rand::thread_rng());
let address = signer.address();
let provider = SignerMiddleware::new(provider, signer);
// Use EthGasStation as the gas oracle
let gas_oracle = EthGasStation::new(None);
let provider = GasOracleMiddleware::new(provider, gas_oracle);
// Manage nonces locally
let provider = NonceManagerMiddleware::new(provider, address);
// ... do something with the provider
```