get_metadata_on_rust.rs

use metadata::{RuntimeMetadata, RuntimeMetadataV4, RuntimeMetadataPrefixed};
use parity_codec::Decode;
use serde_json::json;
use sr_primitives::OpaqueMetadata;
use ws::{connect, CloseCode};
use jsonrpc_core_client::transports::parse_response;
use jsonrpc_core::Value;
use url::form_urlencoded::Target;


fn main() {
    // Connect to the url and call the closure
    
    if let Err(error) = connect("ws://127.0.0.1:9944", |out| {
        let req = json!({
            "method": "chain_getBlockHash",
            "params": [],
            "jsonrpc": "2.0",
            "id": "1",
        })
            .to_string();
        // Queue a message to be sent when the WebSocket is open
        if out.send(req.clone()).is_err() {
            println!("Websocket couldn't queue an initial message.")
        } else {
            println!("Client sent message {}. ", req)
        }

        // The handler needs to take ownership of out, so we use move
        move |msg: ws::Message| {
            // Handle messages received on this connection
            println!("Client got message '{}'. ", msg);
            println!("Client got message '{}'. ", msg.is_binary());
            out.close(CloseCode::Normal)
        }
    }) {
        // Inform the user of failure
        println!("Failed to create WebSocket due to: {:?}", error);
    }

    if let Err(error) = connect("ws://127.0.0.1:9944", |out| {
        let req = json!({
            "method": "state_getMetadata",
            "params": ["0x4c61f1b0a5f0311a42fa08c0edf229e94fe2cc210d1ab2a0460209c39d96e241"],
            "jsonrpc": "2.0",
            "id": "2",
        })
            .to_string();
        // Queue a message to be sent when the WebSocket is open
        if out.send(req.clone()).is_err() {
            println!("Websocket couldn't queue an initial message.")
        } else {
            println!("Client sent message {}. ", req)
        }

        move |msg: ws::Message| {
            // Handle messages received on this connection
            println!("Client got message '{}'. ", msg);
            let mut res = parse_response(&msg.as_text().expect("as_text"));
            if let Value::String(s) = res.as_mut().expect("ok parse response")[0].1.as_mut().expect("no error") {
                let binary = hex::decode(s.split_off(2)).expect("ok");
                let metadata = RuntimeMetadataPrefixed::decode(&mut &binary[..]).expect("unk3");
                println!("Get Vec<u8>: {:?}.", metadata);
//                let meta_p = RuntimeMetadataPrefixed::decode(&mut &(*metadata)[..]).expect("unk4");
//                println!("Get JSON: {:?}.", meta_p);
            }
            // Close the connection
            out.close(CloseCode::Normal)
        }
    }) {
        // Inform the user of failure
        println!("Failed to create WebSocket due to: {:?}", error);
    }
}