Exth

Exth is an Elixir client for interacting with EVM-compatible blockchain nodes via JSON-RPC. It provides a robust, type-safe interface for making Ethereum RPC calls.

Features

• 🔒 Type Safety: Comprehensive type specs and validation
• 🔄 Transport Agnostic: Pluggable transport system (HTTP, WebSocket, IPC)
• 🎯 Smart Defaults: Sensible defaults with full configurability
• 🛡️ Error Handling: Detailed error reporting and recovery
• 📦 Batch Support: Efficient batch request processing
• 🔌 Protocol Compliance: Full JSON-RPC 2.0 specification support

Installation

Add exth to your list of dependencies in mix.exs:

def deps do
  [
    {:exth, "~> 0.1.0"},
    # Optional dependencies:
    # Mint for Tesla adapter
    {:mint, "~> 1.7"}
  ]
end

Usage

Exth offers two ways to interact with EVM nodes:

1. Provider (High-Level): Define a provider module with convenient function names and no need to pass client references.
2. Client (Low-Level): Direct client usage with more control, requiring explicit client handling.

Provider (Recommended)

defmodule MyProvider do
  use Exth.Provider,
    transport_type: :http,
    rpc_url: "https://YOUR-RPC-URL"
end

{:ok, block_number} = MyProvider.block_number()

{:ok, balance} = MyProvider.get_balance(
  "0x742d35Cc6634C0532925a3b844Bc454e4438f44e",
  "latest"
)

{:ok, block} = MyProvider.get_block_by_number("0x1", true)

{:ok, tx_hash} = MyProvider.send_raw_transaction("0x...")

The Provider approach is recommended for most use cases as it provides:

• ✨ Clean, intuitive function names
• 🔒 Type-safe parameters
• 📝 Better documentation and IDE support
• 🎯 No need to manage client references

Client

alias Exth.Client

# 1. Define a client
{:ok, client} = Client.new(
  transport_type: :http,
  rpc_url: "https://YOUR-RPC-URL"
)

# 2.1. Make RPC calls with explicit client
request1 = Client.request(client, "eth_blockNumber", [])
{:ok, block_number} = Client.send(client, request1)

# 2.2. Or make RPC calls without a client
request2 = Client.request(
  "eth_getBalance",
  ["0x742d35Cc6634C0532925a3b844Bc454e4438f44e", "latest"]
)
{:ok, balance} = Client.send(client, request2)

# 3. You can also send multiple requests in one call
requests = [request1, request2]
{:ok, responses} = Client.send(client, requests)

# 4. You can invert the order of the arguments and pipe
Client.request("eth_blockNumber", [])
|> Client.send(client)

# OR
[request1, request2]
|> Client.send(client)

Use the Client approach when you need:

• 🔧 Direct control over RPC calls
• 🔄 Dynamic method names
• 🛠️ Custom parameter handling
• 🎛️ Flexible client management (multiple clients, runtime configuration)

Transport Options

Exth uses a pluggable transport system that supports different communication protocols. Each transport type can be configured with specific options:

HTTP Transport

The default HTTP transport is built on Tesla, providing a robust HTTP client with middleware support:

# Provider configuration
defmodule MyProvider do
  use Exth.Provider,
    transport_type: :http,
    rpc_url: "https://eth-mainnet.example.com",
    # Optional HTTP-specific configuration
    adapter: Tesla.Adapter.Mint, # Default HTTP adapter
    headers: [{"authorization", "Bearer token"}],
    timeout: 30_000, # Request timeout in ms
end

# Direct client configuration
{:ok, client} = Exth.Client.new(
  transport_type: :http,
  rpc_url: "https://eth-mainnet.example.com",
  adapter: Tesla.Adapter.Mint,
  headers: [{"authorization", "Bearer token"}],
  timeout: 30_000
)

• ✨ HTTP (:http)

  • Built on Tesla HTTP client
  • Configurable adapters (Mint, Hackney, etc.)
  • Configurable headers and timeouts

Custom Transport

Implement your own transport by creating a module and implementing the Exth.Transport.Transportable protocol:

defmodule MyCustomTransport do
  # Transport struct should be whatever you need
  defstruct [:config]
end

defimpl Exth.Transport.Transportable, for: MyCustomTransport do
  def new(transport, opts) do
    # Initialize your transport configuration
    %MyCustomTransport{config: opts}
  end

  def call(transport, request) do
    # Handle the JSON-RPC request
    # Return {:ok, response} or {:error, reason}
  end
end

# Use your custom transport
defmodule MyProvider do
  use Exth.Provider,
    transport_type: :custom,
    module: MyCustomTransport,
    rpc_url: "custom://endpoint",
    # Additional custom options
    custom_option: "value"
end

# Direct client configuration
{:ok, client} = Exth.Client.new(
  transport_type: :custom,
  rpc_url: "https://eth-mainnet.example.com",
  module: MyCustomTransport,
  custom_option: "value"
)

• 🔧 Custom (:custom)
  • Full control over transport implementation
  • Custom state management

Examples

Check out our examples directory for practical usage examples:

• multichain.exs

  Working with multiple chains/providers

• More examples coming soon!

To run an example:

mix run --no-mix-exs examples/multichain.exs

Requirements

• Elixir ~> 1.18
• Erlang/OTP 26 or later

Contributing

1. Fork it
2. Create your feature branch (git checkout -b feature/my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin feature/my-new-feature)
5. Create new Pull Request

License

This project is licensed under the MIT License. See LICENSE for details.