Elixir JSON-RPC client for the Ethereum blockchain
Check out the documentation here
Add Ethereumex to your mix.exs
dependencies:
- Add
ethereumex
to your list of dependencies inmix.exs
:
def deps do
[{:ethereumex, "~> 0.5.0"}]
end
- Ensure
ethereumex
is started before your application:
def application do
[applications: [:ethereumex]]
end
In config/config.exs
, add Ethereum protocol host params to your config file
config :ethereumex,
url: "http://localhost:8545"
You can also configure the HTTP
request timeout for requests sent to the Ethereum JSON-RPC
(you can also overwrite this configuration in opts
used when calling the client):
config :ethereumex,
http_options: [timeout: 8000, recv_timeout: 5000]
:timeout - timeout to establish a connection, in milliseconds. Default is 8000 :recv_timeout - timeout used when receiving a connection. Default is 5000
If you want to use IPC you will need to set a few things in your config.
First, specify the :client_type
:
config :ethereumex,
client_type: :ipc
This will resolve to :http
by default.
Second, specify the :ipc_path
:
config :ethereumex,
ipc_path: "/path/to/ipc"
The IPC client type mode opens a pool of connection workers (default is 5 and 2, respectively). You can configure the pool size.
config :ethereumex,
ipc_worker_size: 5,
ipc_max_worker_overflow: 2,
ipc_request_timeout: 60_000
- web3_clientVersion
- web3_sha3
- net_version
- net_peerCount
- net_listening
- eth_protocolVersion
- eth_syncing
- eth_coinbase
- eth_mining
- eth_hashrate
- eth_gasPrice
- eth_accounts
- eth_blockNumber
- eth_getBalance
- eth_getStorageAt
- eth_getTransactionCount
- eth_getBlockTransactionCountByHash
- eth_getBlockTransactionCountByNumber
- eth_getUncleCountByBlockHash
- eth_getUncleCountByBlockNumber
- eth_getCode
- eth_sign
- eth_sendTransaction
- eth_sendRawTransaction
- eth_call
- eth_estimateGas
- eth_getBlockByHash
- eth_getBlockByNumber
- eth_getTransactionByHash
- eth_getTransactionByBlockHashAndIndex
- eth_getTransactionByBlockNumberAndIndex
- eth_getTransactionReceipt
- eth_getUncleByBlockHashAndIndex
- eth_getUncleByBlockNumberAndIndex
- eth_getCompilers
- eth_compileLLL
- eth_compileSolidity
- eth_compileSerpent
- eth_newFilter
- eth_newBlockFilter
- eth_newPendingTransactionFilter
- eth_uninstallFilter
- eth_getFilterChanges
- eth_getFilterLogs
- eth_getLogs
- eth_getWork
- eth_submitWork
- eth_submitHashrate
- db_putString
- db_getString
- db_putHex
- db_getHex
- shh_post
- shh_version
- shh_newIdentity
- shh_hasIdentity
- shh_newGroup
- shh_addToGroup
- shh_newFilter
- shh_uninstallFilter
- shh_getFilterChanges
- shh_getMessages
You can follow along with any of these examples using IPC by replacing HttpClient
with IpcClient
.
iex> Ethereumex.HttpClient.web3_client_version
{:ok, "Parity//v1.7.2-beta-9f47909-20170918/x86_64-macos/rustc1.19.0"}
# Using the url option will overwrite the configuration
iex> Ethereumex.HttpClient.web3_client_version(url: "http://localhost:8545")
{:ok, "Parity//v1.7.2-beta-9f47909-20170918/x86_64-macos/rustc1.19.0"}
iex> Ethereumex.HttpClient.web3_sha3("wrong_param")
{:error, %{"code" => -32602, "message" => "Invalid params: invalid format."}}
iex> Ethereumex.HttpClient.eth_get_balance("0x407d73d8a49eeb85d32cf465507dd71d507100c1")
{:ok, "0x0"}
Note that all method names are snakecases, so, for example, shh_getMessages method has corresponding Ethereumex.HttpClient.shh_get_messages/1 method. Signatures can be found in Ethereumex.Client.Behaviour. There are more examples in tests.
In order to call a smart contract using the JSON-RPC interface you need to properly hash the data attribute (this will need to include the contract method signature along with arguments if any). You can do this manually or use a hex package like (ABI)[https://github.com/exthereum/abi] to parse your smart contract interface or encode individual calls.
defp deps do
[
...
{:ethereumex, "~> 0.4.0"},
{:abi, "~> 0.1.8"}
...
]
end
Now load the abi and pass the method signature. Note that the address needs to be converted to bytes
address = "0x123" |> String.slice(2..-1) |> Base.decode16(case: :mixed)
contract_address = "0x432"
abi_encoded_data = ABI.encode("balanceOf(address)", [address]) |> Base.encode16(case: :lower)
Now you can use eth_call to execute this smart contract command:
balance_bytes = Ethereumex.HttpClient.eth_call(%{
data: "0x" <> abi_encoded_data,
to: contract_address
})
To convert the balance into an integer:
balance_bytes
|> String.slice(2..-1)
|> Base.decode16!(case: :lower)
|> TypeDecoder.decode_raw([{:uint, 256}])
|> List.first
Calling a smart contract method that requires computation will cost you gas or ether (if that method requires payment also). This means you will have to sign your transactions using the private key that owns some ethereum. In order to send signed transactions you will need both ABI and Blockchain hex packages.
abi_encoded_data = ABI.encode("transferFrom(address,address,uint)", [from_address, to_address, token_id])
contract_address = "0x123" |> String.slice(2..-1) |> Base.decode16(case: :mixed)
transaction_data = %Blockchain.Transaction{
data: abi_encoded_data,
gas_limit: 100_000,
gas_price: 16_000_000_000,
init: <<>>,
nonce: 5,
to: contract_address,
value: 0
}
|> Blockchain.Transaction.Signature.sign_transaction(private_key)
|> Blockchain.Transaction.serialize()
|> ExRLP.encode()
|> Base.encode16(case: :lower)
Ethereumex.HttpClient.eth_send_raw_transaction("0x" <> transaction_data)
Many Ethereum protocol implementations support additional JSON-RPC API methods. To use them, you should call Ethereumex.HttpClient.request/3 method.
For example, let's call parity's personal_listAccounts method.
iex> Ethereumex.HttpClient.request("personal_listAccounts", [], [])
{:ok,
["0x71cf0b576a95c347078ec2339303d13024a26910",
"0x7c12323a4fff6df1a25d38319d5692982f48ec2e"]}
To send batch requests use Ethereumex.HttpClient.batch_request/1 method.
requests = [
{:web3_client_version, []},
{:net_version, []},
{:web3_sha3, ["0x68656c6c6f20776f726c64"]}
]
Ethereumex.HttpClient.batch_request(requests)
{
:ok,
[
"Parity//v1.7.2-beta-9f47909-20170918/x86_64-macos/rustc1.19.0",
"42",
"0x47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad"
]
}
- Fork it!
- Create your feature branch (
git checkout -b my-new-feature
) - Commit your changes (
git commit -am 'Add some feature'
) - Push to the branch (
git push origin my-new-feature
) - Create new Pull Request
Ayrat Badykov (@ayrat555)
Ethereumex is released under the MIT License.