Syscoin + ZMQ + Node.js = Realtime Blockchain Updates!

Realtime Updates from the Syscoin Blockchain

You can use the ZMQ topic message queues in Syscoin to receive realtime updates for your application. Using in conjunction with syscoin-core to blockchain-enable your applications in no time.

Syscoin Configuration

Make sure to enable the ZMQ listeners in your syscoin.conf file and restart syscoind or Syscoin Core Qt.

# 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

Create ZMQ Client

You will need to npm install the module zeromq.

const zeromq = require('zeromq');

const subscriber = zeromq.socket('sub');
subscriber.on('message', async (topic, message) => {
  topic = topic.toString('utf8');
  message = message.toString('utf8')
  const alias = JSON.parse(message);
  console.log(JSON.stringify(alias, null, 2));
});

// connect to message producer
subscriber.connect('tcp://127.0.0.1:3030');
subscriber.subscribe('aliasrecord');
console.log('subscribed to syscoin topic aliasrecord');

Run your script with the following:

> node zmq-client.js 
subscribed to syscoin topic aliasrecord
{
  "_id": "gldm1",
  "address": "SRxK2GjfzTrm8z5PgCtLKzheN5ebd5kN8f",
  "expires_on": 1590601936,
  "encryption_privatekey": "",
  "encryption_publickey": ""
}
{
  "_id": "elatte",
  "address": "Sd8JMHxtuFVSVJN2V51M27S6MkBBMjgjHY",
  "expires_on": 1559077278,
  "encryption_privatekey": "",
  "encryption_publickey": ""
}
{
  "_id": "primitive7",
  "address": "Sk7q3kZcttBNVkUwpMXU59yQf9Pco4sAAJ",
  "expires_on": 1558656041,
  "encryption_privatekey": "",
  "encryption_publickey": ""
}
{
  "_id": "primitive9",
  "address": "SYKff6VzkrzmSn9tL3zZE7FmV2dGFSKfxs",
  "expires_on": 1558656041,
  "encryption_privatekey": "",
  "encryption_publickey": ""
}
// ....