Updated on August 6, 2020

Creating and sending transactions

You can send signed transactions using the eth_sendRawTransaction JSON-RPC API method.

Signed transactions can be simple value transfers, contract creation, or contract invocation. Set the maximum transaction fee for transactions using the --rpc-tx-feecap CLI option.

Use client libraries to create and send a signed raw transaction to transfer Ether and create a smart contract.

Private keys

Do not use the accounts from the examples on Mainnet or any public network except for testing. The private keys are displayed which means the accounts are not secure.

All accounts and private keys in the examples are from the dev.json genesis file in the /besu/config/src/main/resources directory.

In production environments avoid exposing your private keys by creating signed transactions offline, or use EthSigner to isolate your private keys and sign transactions with eth_sendTransaction.

Tip

Libraries such as web3j or ethereumj and tools such as MyCrypto can also create signed transactions.

eth_call vs eth_sendRawTransaction

You can interact with contracts using eth_call or eth_sendRawTransaction. The table below compares the characteristics of both calls.

eth_call	eth_sendRawTransaction
Read-only	Write
Invokes contract function locally	Broadcasts to the network
Does not change state of blockchain	Updates the blockchain (for example, transfers ether between accounts)
Does not consume gas	Requires gas
Synchronous	Asynchronous
Returns the value of a contract function available immediately	Returns transaction hash only. A block might not include all possible transactions (for example, if the gas price is too low).