Example of subscribing to logs from the Ethereum network using an ext…

…ernal provider. (#59)

* mod: added subscribe_to_log_external_provider

* mod: rpc filtering update

* fmt

examples/subscriptions/examples/subscribe_to_log_external_provider.rs

@@ -0,0 +1,38 @@
+//! Example of subscribing to logs from the Ethereum network using an external provider.
+
+use alloy::{
+    primitives::{address, b256},
+    providers::{Provider, ProviderBuilder},
+    rpc::{
+        client::WsConnect,
+        types::eth::{BlockNumberOrTag, Filter},
+    },
+};
+use eyre::Result;
+use futures_util::stream::StreamExt;
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let uniswap_token_address = address!("1f9840a85d5aF5bf1D1762F925BDADdC4201F984");
+    let tranfer_event_signature =
+        b256!("ddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef");
+    let filter = Filter::new()
+        .address(uniswap_token_address)
+        .event_signature(tranfer_event_signature)
+        .from_block(BlockNumberOrTag::Latest);
+
+    let rpc_url = "wss://eth.merkle.io"; // DON'T use wss://eth.merkle.io _> this filters wrongly, tested alchemy.io's to be working fine
+
+    // Create the provider.
+    let ws = WsConnect::new(rpc_url);
+    let provider = ProviderBuilder::new().on_ws(ws).await.unwrap();
+
+    let sub = provider.subscribe_logs(&filter).await.expect("Failed to subscribe to logs");
+    let mut stream = sub.into_stream();
+
+    while let Some(log) = stream.next().await {
+        println!("Uniswap token logs: {log:?}");
+    }
+
+    Ok(())
+}