katopz / solana-feed-rs

solana-feed-rs

Solana web app built with Rust

Project Structure

crates/
- contract/ - Rust smart contract code
- contract-data/ - Rust smart contract data types
- solana-bindgen/ - Rust lib that binds to global values from JS
- solana-contract-types/ - Solana BPF SDK data types
- solana-contract-utils/ - Solana BPF SDK
- webapp/ - Rust web app

• I chose to split up contract data types from implementation since that was all I wanted to depend on in webapp but ultimately I don't think that was necessary.
• solana-bindgen uses wasm-bindgen to bind to JS. The JS can either be a module, a local file, or a global [docs]. I wasn't aware of binding to a module so I hacked solana-web3.js to export some global variables 😅.
• webapp depends on solana/sdk but I had to feature gate the memmap dependency which is used for generating the genesis block because it doesn't support WASM.
• webapp was unable to leverage solana/client because WASM doesn't have support for I/O and threading. You have to bind to JS in order to make http requests and use WebSockets for example. More details here.

Wins

• Deserialization from JS values is pretty great with serde_wasm_bindgen

serde_wasm_bindgen::from_value<solana_sdk::account::Account>(js_val);

• It was super easy to read from buffers into the contract data types

message_feed_contract::MessageAccountData::new(account.data.as_mut_slice());

• Calling into solana-web3.js was pretty seamless once the bindings were written

use solana_bindgen::{Connection, PublicKey};
use solana_sdk::pubkey::Pubkey;
let js_connection = Connection::new("https://api.beta.testnet.solana.com");
let pubkey = Pubkey::from_str("J56CEQXnxkEvQ7yT1D82gu9fG5t6ykWC3eu4nUABXabt").unwrap();
let js_key = PublicKey::new(pubkey.as_ref().to_vec());
js_connection.get_account_info(js_key).then(/* closure */);

Going Forward

• Building out a wasm friendly solana client would be pretty ideal for webapp development with Rust.
  • This would require JS or WASM-friendly JSON RPC and WebSocket clients. The former would require wasm bindings.
  • A wasm friendly client in Rust could be distributed as an NPM package using wasm-pack
  • Wouldn't need to bind to the solana-web3.js module
• Binding to solana-web3.js could be a pain
  • It's possible that you could generate the bindings somehow from Flow but haven't looked into it.
  • For this proof of concept, I had to manually write up all the bindings and there were no compile time guarantees that I got it right