Ethereumex (ethereumex v0.9.0) View Source
Elixir JSON-RPC client for the Ethereum blockchain.
Check out the documentation here.
Installation
Add :ethereumex
to your list of dependencies in mix.exs
:
def deps do
[
{:ethereumex, "~> 0.9"}
]
end
Ensure :ethereumex
is started before your application:
def application do
[
applications: [:ethereumex]
]
end
Configuration
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: [pool_timeout: 5000, receive_timeout: 15_000],
http_headers: [{"Content-Type", "application/json"}]
:pool_timeout
- This timeout is applied when we check out a connection from the pool. Default value is 5_000
.
:receive_timeout
- The maximum time to wait for a response before returning an error. Default value is 15_000
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"
If you want to count the number of RPC calls per RPC method or overall,
you can attach yourself to executed telemetry events.
There are two events you can attach yourself to:
[:ethereumex]
# has RPC method name in metadata
Emitted event: {:event, [:ethereumex], %{counter: 1}, %{method_name: "method_name"}}
or more granular
[:ethereumex, <rpc_method>]
# %{} metadata
Emitted event: {:event, [:ethereumex, :method_name_as_atom], %{counter: 1}, %{}}
Each event caries a single ticker that you can pass into your counters (like Statix.increment/2
).
Be sure to add :telemetry as project dependency.
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
Usage
Available methods:
- 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_getProof
- 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
IpcClient
You can follow along with any of these examples using IPC by replacing HttpClient
with IpcClient
.
Examples
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.
eth_call example - Read only smart contract calls
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 to parse your smart contract interface or encode individual calls.
defp deps do
[
...
{:ethereumex, "~> 0.8"},
{:ex_abi, "~> 0.5"}
...
]
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
Custom requests
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"]}
Batch requests
To send batch requests use Ethereumex.HttpClient.batch_request/1 or Ethereumex.HttpClient.batch_request/2 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"
]
}
Link to this section Summary
Functions
Callback implementation for Application.start/2
.
Link to this section Functions
Callback implementation for Application.start/2
.