<p>ZeroMQ is a publisher / subscriber messaging system. In the case of Bitcoin Core it is a socket which other applications can connect to and get notifications of new events in real time, without having to repeatedly ask the daemon if there are any new events. ZMQ support is useful for any systems interfacing with the network like miners and wallets, which can choose to subscribe either to just transaction notifications or block notifications as their situation requires. It covers a lot of the same use area as the prexisting <code>walletnotify</code> and <code>blocknotify</code> systems, but with significantly improved performance and ease of configuration. These older systems have the unfortunate side effect of spawning a new process for every notification, which tends to incapacitate the host if not used extremely carefully. </p>

CC BY-SA 3.0
2015-10-04T19:27:18.403Z
It currently (upcoming 0.12 release) does not support `walletnotify`-likes notifications. Only notifications for new blocks or transactions.
Jonas Schnelli
CC BY-SA 3.0
2015-10-04T22:07:22.600Z
@JonasSchnelli I'll re-write that to be clearer, I meant you can emulate `walletnotify` by simply subscribing to all transactions and doing your own `IsMine()`-style filtering externally.
Claris
CC BY-SA 3.0
2015-10-03T21:56:58.127Z
2015-10-03T21:56:58.127Z
Claris
<p>What is the use case of ZeroMQ implementation for bitcoind which will be merged into Bitcoin Core v0.12.0?</p>

<p>Block and Transaction Broadcasting With ZeroMQ
<a href="https://github.com/bitcoin/bitcoin/blob/master/doc/zmq.md" rel="noreferrer">https://github.com/bitcoin/bitcoin/blob/master/doc/zmq.md</a></p>

<bitcoind><bitcoin-core><zeromq>
What is the use case of bitcoind ZeroMQ?
Satoshi Nakanishi
# What is the use case of bitcoind ZeroMQ?

(Asked by: username_0 on 2015-10-03)

What is the use case of ZeroMQ implementation for bitcoind which will be merged into Bitcoin Core v0.12.0?

Block and Transaction Broadcasting With ZeroMQ
<https://github.com/bitcoin/bitcoin/blob/master/doc/zmq.md>

**Tags:** bitcoind, bitcoin-core, zeromq


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## 1 answers

### Answer by username_1 on 2015-10-03. Score: 27 | Accepted answer

ZeroMQ is a publisher / subscriber messaging system. In the case of Bitcoin Core it is a socket which other applications can connect to and get notifications of new events in real time, without having to repeatedly ask the daemon if there are any new events. ZMQ support is useful for any systems interfacing with the network like miners and wallets, which can choose to subscribe either to just transaction notifications or block notifications as their situation requires. It covers a lot of the same use area as the prexisting `walletnotify` and `blocknotify` systems, but with significantly improved performance and ease of configuration. These older systems have the unfortunate side effect of spawning a new process for every notification, which tends to incapacitate the host if not used extremely carefully.

> **Comments:**
> **username_2**: It currently (upcoming 0.12 release) does not support `walletnotify`-likes notifications. Only notifications for new blocks or transactions.  
> **username_1**: @username_2 I'll re-write that to be clearer, I meant you can emulate `walletnotify` by simply subscribing to all transactions and doing your own `IsMine()`-style filtering externally.  

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