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#!/usr/bin/env python3
# Copyright (c) 2014-2018 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or
ZMQ example using python3's asyncio
Bitcoin should be started with the command line arguments:
bitcoind -testnet -daemon \
-zmqpubrawtx=tcp:// \
-zmqpubrawblock=tcp:// \
-zmqpubhashtx=tcp:// \
We use the asyncio library here. `self.handle()` installs itself as a
future at the end of the function. Since it never returns with the event
loop having an empty stack of futures, this creates an infinite loop. An
alternative is to wrap the contents of `handle` inside `while True`.
A blocking example using python 2.7 can be obtained from the git history:
import binascii
import asyncio
import zmq
import zmq.asyncio
import signal
import struct
import sys
if (sys.version_info.major, sys.version_info.minor) < (3, 5):
print("This example only works with Python 3.5 and greater")
port = 28332
class ZMQHandler():
def __init__(self):
self.loop = asyncio.get_event_loop()
self.zmqContext = zmq.asyncio.Context()
self.zmqSubSocket = self.zmqContext.socket(zmq.SUB)
self.zmqSubSocket.setsockopt(zmq.RCVHWM, 0)
self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashblock")
self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashtx")
self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawblock")
self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawtx")
self.zmqSubSocket.connect("tcp://" % port)
async def handle(self) :
msg = await self.zmqSubSocket.recv_multipart()
topic = msg[0]
body = msg[1]
sequence = "Unknown"
if len(msg[-1]) == 4:
msgSequence = struct.unpack('<I', msg[-1])[-1]
sequence = str(msgSequence)
if topic == b"hashblock":
print('- HASH BLOCK ('+sequence+') -')
elif topic == b"hashtx":
print('- HASH TX ('+sequence+') -')
elif topic == b"rawblock":
print('- RAW BLOCK HEADER ('+sequence+') -')
elif topic == b"rawtx":
print('- RAW TX ('+sequence+') -')
# schedule ourselves to receive the next message
def start(self):
self.loop.add_signal_handler(signal.SIGINT, self.stop)
def stop(self):
daemon = ZMQHandler()
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