RPC

Rusty Kaspa integrates support for the following RPC protocols:

• gRPC (native to Kaspa)
• WebSocket-framed wRPC/JSON-RPC protocol
• WebSocket-framed wRPC/Borsh protocol

When using Borsh, server and client should be built from the same source.

gRPC

gRPC connection can be established by any gRPC-capable client and follow for Kaspa gRPC protocol specifications.

wRPC

Protocol encoding for wRPC is configurable within the initialization API or as command line switches in applications such as kaspa-wrpc-proxy or Rusty Kaspa full-node daemon.

Rusty Kaspa framework includes RPC client and server offering creation of wRPC endpoints easily from within Rust as well as from within JavaScript using WASM SDK.

WASM RpcClient

RpcClient Documentation

• JSDoc - https://aspectron.com/docs/kaspa-wasm/RpcClient.html
• Rustdoc - https://docs.rs/kaspa_wasm/latest/kaspa_wasm/rpc/trait.RpcApi.html

Example

The following example runs under NodeJS and registers to receive a certain number of notifications, after which it cleanly shuts-down and exits.

We start by declaring a websocket shim needed for the RPC connection in NodeJS, then we load required imports and initialize the RPC client.

// W3C WebSocket module shim
globalThis.WebSocket = require('websocket').w3cwebsocket;

let {RpcClient,Encoding,defer} = require('./kaspa-rpc');

const MAX_NOTIFICATIONS = 10;
let URL = "ws://127.0.0.1:17110";
let rpc = new RpcClient(Encoding.Borsh, URL);

Once we have the RPC client, we call an async connect() function that bloks the async execution until the connection is resolved.

(async () => {
    // ...
    await rpc.connect();
    // ...

Once connected, you can make RPC requests to the Kaspa daemon. RPC functions are always async and currently return pure JavaScript objects. For example getInfo() will return an object as follows:

    let info = await rpc.getInfo();
    console.log(info);
    // {
    //   serverVersion : "0.12.8",
    //   isSynced : false,
    //   ...
    // }

You can also subscribe for event notifications using rpc.notify() function to register a notification handler callback. In this example defer() returns a "deferred promise" that can be resolved manually at a later time.

    let finish = defer();
    let seq = 0;
    // register notification handler
    await rpc.notify(async (op, payload) => {
        console.log(`#${seq} - `,"op:",op,"payload:",payload);
        seq++;
        if (seq == MAX_NOTIFICATIONS) {
            // await rpc.disconnect();
            console.log(`exiting after ${seq} notifications`);
            finish.resolve();
        }
    });

    // test subscription
    console.log("subscribing...");
    await rpc.subscribeDaaScore();

At this point we block on the finish promise, and wait for MAX_NOTIFICATIONS to occur. The notification handler will execute finish.resolve() after MAX_NOTIFICATIONS, allowing the await finish; to resolve and the execution on the primary async pathway to continue.

We then unregister the notification handler to cleanup by calling rpc.notify(null); and rpc.disconnect() to disconnect from the RPC endpoint.

    // wait until notifier signals completion
    await finish;
    // clear notification handler
    await rpc.notify(null);
    // disconnect RPC interface
    await rpc.disconnect();

})();