Package org.polkadot.rpc.core

@polkadot/rpc-core

See: Description

Interface Summary

Interface	Description
IRpc

Class Summary

Class	Description
IRpc.RpcInterfaceSection
RpcCore

Package org.polkadot.rpc.core Description

@polkadot/rpc-core

This library provides a clean wrapper around all the methods exposed by a Polkadot network client.

Usage

Installation -

yarn add @polkadot/rpc-core

Initialisation -

import org.polkadot.rpc.core.RpcCore;
import org.polkadot.rpc.provider.ws.WsProvider;

const provider = new WsProvider('http://127.0.0.1:9944');
const api = new RpcCore(provider);

Retrieving the block header object for a given block header hash (a 0x-prefixed hex string with length of 64) -

api.chain
 .getHeader("0x1234567890")
 .then((header) => System.out.println(header))
 .catch((error) => System.out.println(error));

Retrieving the best block number, parent hash, state root hash, extrinsics root hash, and digest (once-off) -

api.chain
 .getHead()
 .then((headerHash) => {
   return api.chain.getHeader(headerHash);
 })
 .then((header) => {
   System.out.print("best ");
   System.out.println(header.blockNumber.toString());
   System.out.print("parentHash: ");
   System.out.println(header.parentHash.toString());
   System.out.print("stateRoot: ");
   System.out.println(header.stateRoot.toString());
   System.out.print("extrinsicsRoot: ");
   System.out.println(header.extrinsicsRoot.toString());
   System.out.print("digest: ");
   System.out.println(header.digest.toString());
 })
 .catch((error) => {
   System.out.println(error);
 });

Retrieving best header via subscription -

api.chain
 .subscribeNewHead((header) => {
   System.out.print("best ");
   System.out.println(header.blockNumber);
 })
 .then((subscriptionId) => {
   System.out.print("subscriptionId: ");
   System.out.println(subscriptionId);
   // id for the subscription, can unsubscribe via
   // api.chain.subscribeNewHead.unsubscribe(subscriptionId);
 })
 .catch((error) => {
   System.out.println(error);
 });