ethers-rs/book/providers/providers.md

Providers

A Provider is an abstraction of a connection to the Ethereum network, providing a concise, consistent interface to standard Ethereum node functionality.

This is achieved through the Middleware trait, which provides the interface for the Ethereum JSON-RPC API and other helpful methods, explained in more detail in the Middleware chapter, and the Provider struct, which implements Middleware.

Data transports

A Provider wraps a generic data transport P, through which all JSON-RPC API calls are routed.

Ethers provides concrete transport implementations for HTTP, WebSockets, and IPC, as well as higher level transports which wrap a single or multiple transports. Of course, it is also possible to define custom data transports.

Transports implement the JsonRpcClient trait, which defines a request method, used for sending data to the underlying Ethereum node using JSON-RPC.

Transports can optionally implement the PubsubClient trait, if they support the Publish-subscribe pattern, like Websockets and IPC. This is a supertrait of JsonRpcClient. It defines the subscribe and unsubscribe methods.

The Provider type

This is the definition of the Provider type:

#[derive(Clone, Debug)]
pub struct Provider<P> {
    inner: P,
    ens: Option<Address>,
    interval: Option<Duration>,
    from: Option<Address>,
    node_client: Arc<Mutex<Option<NodeClient>>>,
}

• inner: stores the generic data transport, which sends the requests;
• ens: optional override for the default ENS registry address;
• interval: optional value that defines the polling interval for watch_* streams;
• from: optional address that sets a default from address when constructing calls and transactions;
• node_client: the type of node the provider is connected to, like Geth, Erigon, etc.

Now that you have a basis for what the Provider type actually is, the next few sections will walk through each implementation of the Provider, starting with the HTTP provider.