Viewing A Bitcoin Dedicated Node Transaction with ZMQ

Blockdaemon bitcoin dedicated nodes have ZMQ enabled. ZMQ is a message queue that allows programs to subscribe to events. You can use this to be notified when new transactions or new blocks occur on your Bitcoin connection.

This tutorial shows a simple Python application that prints each new transaction as well as the total value of all the transactions outputs.

The following text assumes a basic working knowledge of Python and pip.

Install Python libraries

Install the Python library ZMQ. We will use this library to listen to the bitcoin events:

 input type="text" value="pip3 install zmq" readonly="true"

Install the Python library bitcoin. We will use this library to convert the raw bitcoin transactions into a simpler format:

 input type="text" value="pip3 install bitcoin" readonly="true"

Copy script

Copy the following Python program into a file called bitcoin_zmq.py

import binascii
import sys
import zmq
import bitcoin
import pprint

context = zmq.Context()
socket = context.socket(zmq.SUB)

# Connect to ZMQ
socket.connect("tcp://[your node's URL from the Connect page]:28332")

# Subscribe to all new raw transactions
socket.setsockopt_string(zmq.SUBSCRIBE, u"rawtx")

# Loop until the user presses CTRL+c

while True:
    # Wait for the next raw transaction
    msg = socket.recv_multipart()
    topic = msg[0]
    body = msg[1]

    # Convert the binary transaction into a simple dict
    tx = bitcoin.deserialize(body)

    # Calculate the total value of all outputs
    total_value = 0
    for out in tx['outs']:
        total_value += out['value']

    # Print the result
    if total_value / 100000000.0 > 10:
        print("")
        print("New transaction: {}".format(bitcoin.txhash(body)))
        print("Total value of all outputs: {} BTC".format(total_value / 100000000.0))

Further Reading

Bitcoin ZMQ Protocol Documentation

ZMQ Documentation