Factory module for creating JSON-RPC transport implementations.

This module provides a unified interface for creating and managing different transport mechanisms (HTTP, WebSocket, IPC) for JSON-RPC communication with EVM nodes.

Features

• Pluggable transport system via the Transportable protocol
• Built-in HTTP transport with Tesla/Mint
• Consistent interface across transport types
• Automatic request/response encoding/decoding
• Configurable timeout and retry mechanisms
• Transport-specific option handling

Transport Types

Currently supported:

• :http - HTTP/HTTPS transport using Tesla with Mint adapter
• :custom - Custom transport implementations

Coming soon:

• :ws - WebSocket transport
• :ipc - Unix domain socket transport

Usage

# Create an HTTP transport
transport = Transport.new(:http,
  rpc_url: "https://mainnet.infura.io/v3/YOUR-PROJECT-ID",
  timeout: 30_000,
  headers: [{"authorization", "Bearer token"}]
)

# Make requests
{:ok, response} = Transport.call(transport, request)
{:ok, responses} = Transport.call(transport, [request1, request2])

Configuration

Common options for all transports:

• :rpc_url - (Required) The endpoint URL
• :encoder - (Required) Function to encode requests to JSON
• :decoder - (Required) Function to decode JSON responses

HTTP-specific options:

• :headers - Additional HTTP headers
• :timeout - Request timeout in milliseconds (default: 30000)
• :adapter - Tesla adapter to use (default: Tesla.Adapter.Mint)

Custom Transport Implementation

To implement a custom transport:

1. Define your transport struct:

   defmodule MyTransport do
     defstruct [:config]
   end

2. Implement the Transportable protocol:

   defimpl Exth.Transport.Transportable, for: MyTransport do
     def new(_transport, opts) do
       %MyTransport{config: opts}
     end
   
     def call(transport, request) do
       # Implement request handling
       {:ok, response}
     end
   end

3. Use your transport:

   transport = Transport.new(:custom,
     module: MyTransport,
     rpc_url: "custom://endpoint",
     # other options...
   )

Error Handling

The module uses consistent error handling:

• {:ok, response} - Successful request with decoded response
• {:ok, responses} - Successful batch request with responses
• {:error, reason} - Request failed with detailed reason

HTTP-specific errors:

• {:error, {:http_error, status}} - HTTP error response
• {:error, :timeout} - Request timeout
• {:error, :network_error} - Network connectivity issues

Best Practices

• Use appropriate timeouts for your use case
• Implement retry logic for transient failures
• Handle batch requests efficiently
• Monitor transport health and metrics
• Properly handle connection pooling
• Use secure transport options in production

See Exth.Transport.Transportable for protocol details and Exth.Transport.Http for HTTP transport specifics.