Syscoin + Node.js = Blockchain Apps!

Getting Started

You will need to have syscoind or Syscoin Core Qt running on your system and have node/npm installed. If you don’t have Node.js I recommend installing it via nvm.

Syscoin Configuration

First make sure that syscoind is configured so that you can connect to the RPC server locally. Use the example below, choosing a secret rcpuser, rpcpassword, and optionally changing the rpcport. You will need to use these values later to connect to query the blockchain using Node.js later.

You don’t really need the ZMQ config for this example, but it shows how to tell Syscoin to listen on those ports should you want to implement a Node.js ZMQ client in your application :).

Before making changes be sure to stop Syscoin by running syscoin-cli stop, update the configuration, then run syscoind to start the process again. If you change the config file before stopping Syscoin it will prevent syscoin-cli from being able to communicate with the RPC server properly. Changing the index values may require you to restart with syscoind -reindex.

# server
server=1
daemon=1

# indexes
addressindex=1
txindex=1
litemode=0

# rpc
rpcuser=u
rpcpassword=p
rpcport=8370
rpcallowip=127.0.0.1

# zmq listener config
zmqpubaliasrecord=tcp://127.0.0.1:3030
zmqpubaliashistory=tcp://127.0.0.1:3030
zmqpubaliastxhistory=tcp://127.0.0.1:3030
zmqpubassetrecord=tcp://127.0.0.1:3030
zmqpubassetallocation=tcp://127.0.0.1:3030
zmqpubassethistory=tcp://127.0.0.1:3030
zmqpubcertrecord=tcp://127.0.0.1:3030
zmqpubcerthistory=tcp://127.0.0.1:3030
zmqpubescrowrecord=tcp://127.0.0.1:3030
zmqpubescrowbid=tcp://127.0.0.1:3030
zmqpubescrowfeedback=tcp://127.0.0.1:3030
zmqpubofferrecord=tcp://127.0.0.1:3030
zmqpubofferhistory=tcp://127.0.0.1:3030
zmqpubhashblock=tcp://127.0.0.1:3030
zmqpubhashtx=tcp://127.0.0.1:3030
zmqpubhashtxlock=tcp://127.0.0.1:3030
zmqpubrawblock=tcp://127.0.0.1:3030
zmqpubrawtx=tcp://127.0.0.1:3030
zmqpubrawtxlock=tcp://127.0.0.1:3030

Init Node App

Next create a new folder for your project and create a Node project by running npm init and answering the questions as you see fit. The only module that is required is syscoin-core, a cutting edge version can be found at my fork.

mkdir -p my-syscoin-app && cd my-syscoin-app
npm init
# answer init questions
npm install -S https://github.com/doublesharp/syscoin-core.git#dev-3.0

Create index.js Script

Once syscoin-core is installed you can use the following example to get started. Make sure that the port, username, and password match the values set in your syscoin.conf file.

const SyscoinClient = require('@syscoin/syscoin-core');

const syscoin = new SyscoinClient({
  host: process.env.SYSCOIND_HOST || 'localhost',
  port: process.env.SYSCOIND_PORT || 8370,
  username: process.env.SYSCOIND_USER || 'u',
  password: process.env.SYSCOIND_PASS || 'p',
  timeout: 30000,
});

async function run() {
  // prune expired data!
  const pruneStart = Date.now();
  const prune = await syscoin.pruneSyscoinServices();
  console.log('pruned', prune, 'in', Date.now()-pruneStart, 'ms');

  // get all alias records
  const aliasStart = Date.now();
  const list = await syscoin.listAliases(0);
  console.log('fetched', list.length, 'aliases in', Date.now()-aliasStart, 'ms');

  // get just an array of alias names
  const aliases = list.map((alias) => alias._id);
  // ...etc

  process.exit(0);
}

run();

Wrapping Up

> node index.js
pruned { services_cleaned: 0 } in 341 ms
fetched 15162 aliases in 1685 ms

You can take this same basic structure and turn it into an Express app, etc, depending on the needs of your application. It’s surprisingly easy to get started building blockchain applications with Syscoin!

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