Low-level Ethereum JSON-RPC transport abstraction.

This crate handles RPC connection and request management. It builds an RpcClient on top of the tower Service abstraction, and provides futures for simple and batch RPC requests as well as a unified TransportError type.

Typically, this crate should not be used directly. Most EVM users will want to use the alloy-provider crate, which provides a high-level API for interacting with JSON-RPC servers that provide the standard Ethereum RPC endpoints, or the [alloy-rpc-client] crate, which provides a low-level JSON-RPC API without the specific Ethereum endpoints.

Alloy maintains the following transports:

• alloy-transport-http: JSON-RPC via HTTP.
• alloy-transport-ws: JSON-RPC via Websocket, supports pubsub via alloy-pubsub.
• alloy-transport-ipc: JSON-RPC via IPC, supports pubsub via alloy-pubsub.