ZeroMQ is a good tool to know, because it provides a huge variety of socket and messaging patterns that you can leverage in your infrastructure to solve specific problems without using heavyweight message queues to do the same job. This talk illustrates 4 basic sockets provided by zeromq and the many ways you can use them.

1. https://github.com/soggie/naws

2. Leveraging ZeroMQ for
Node.js
Another tool in your toolbox

3. About Me
• Ruben Tan
• @roguejs (twitter)
• Works in GrabTaxi (Malaysia)
github.com/soggie/naws

5. ZeroMQ
• “zero” as in none, nada, nil, 無
• MQ as in Message Queue

6. Why call ZeroMQ as
so when it is not a
message queue?

7. I know. Wrong meme. Shhh.

8. • Originally conceived as a stock trading
messaging solution
• Moved on to generalizing its purpose
• Adopted BSD Socket API and semantics
• Smart end-point, dump network

9. • ZeroMQ is a networking library with
message queue semantics
• Used primarily for connectivity between
services
• Can be used to facilitate brokerless
message passing topologies

10. Crash Course!
• Socket basics
• Buffering (high watermark)
• Load balancing (outgoing/incoming strategy)
• PUSH socket
• PULL socket
• PUB socket
• SUB socket
• We won’t cover: REQ-REP, XPUB-XSUB, ROUTER-DEALER,
STREAM, PAIR, as well as DEVICES

11. 0MQ Sockets
• Supports:
• inproc, IPC, TCP, pgm, epgm
• Maintains it’s own internal queue
• High watermark controls buffer size
• Has a MUTE strategy
• Has different INCOMING and
OUTGOING strategies

12. MUTE
• Connection states:
• connect() ==> READY
• bind() ==> MUTE
• accept() ==> READY
• 2 kinds of MUTE state: block or drop

13. BLOCK

14. DROP

15. Exhibit A - REQ-REP
https://github.com/soggie/naws/tree/master/test/talk/exhibit-a.js

16. // Bind the REP socket
reply.bind('inproc://exhibit-a');
// Make the REQ socket connect to the REP socket
request.connect('inproc://exhibit-a');
request.on('message', function (msg) {
console.log('---- recv: ' + msg.toString());
});
reply.on('message', function (msg) {
console.log('-- recv: ' + msg.toString());
work(); // Some heavy duty work
reply.send(msg);
console.log('--- send: ' + msg.toString());
});
setInterval(function () {
var msg = color(ran(1000, 1000) + '');
console.log('- send: ' + msg);
request.send(msg);
}, 1000);

17. PUSH
• INCOMING:
none
• OUTGOING:
round-robin
• MUTE:
blocks
PPUUSSHH
1 2 3
4 5 6
AA BB CC

18. Exhibit B
https://github.com/soggie/naws/tree/master/test/talk/exhibit-b.js

19. PULL
AA BB CC
1 2 3
• INCOMING
fair-queue
• OUTGOING
none
• MUTE
block (??) PPUULLLL
4 5 6

20. Exhibit C
https://github.com/soggie/naws/tree/master/test/talk/exhibit-c.js

21. PUB
• INCOMING
none
• OUTGOING
fan-out
• MUTE
drop
PPUUBB
1 1 1
2 2 2
AA BB CC

22. Exhibit D
https://github.com/soggie/naws/tree/master/test/talk/exhibit-d.js

23. SUB
PP PP PP
1 2 3
• INCOMING
fair-queue
• OUTGOING
none
• MUTE
none SSUUBB
4 5 6

24. Exhibit E
https://github.com/soggie/naws/tree/master/test/talk/exhibit-e.js

25. Let’s Build Something

26. • A simple HTTP web server on top of
express
• Uses worker processes to handle requests
• Can add or kill workers any time
• Rudimentary monitoring and reliability

27. Architecture
SSUUBB PPUUBB
RR EExxpprreessss
PPUUSSHH
5
HHaannddlleerr
PPUULLLL
1
2
3
4
6
8 7
Server Process Worker Process

28. Conclusion
• zeromq is a lightweight networking library
• build messaging topologies you want
• nice async features enabling you to do fun
stuff (add/kill workers)
• use to connect apps written in different
languages/tech stacks
• a very useful tool to have and understand

29. Similar & References
• Nanomsg (http://nanomsg.org)
- Martin Sustrik, fork/rewrite of 0mq
• Axon (https://github.com/visionmedia/axon)
- Pure node.js 0mq sockets
• Theory of ZeroMQ
http://250bpm.com/concepts
• ZeroMQ Internal Architecture
http://www.aosabook.org/en/zeromq.html
• Dissecting Message Queues
http://www.bravenewgeek.com/dissecting-message-queues/

30. THE END
Questions?
Questions?