A quick overview about zeroMQ as part of eSpace weekly techtalks

1. Introduction to ZeroMQ
eSpace TechTalks
@modsaid

2. Outline
● Quick Definition
● Creators
● Why ØMQ?
● What the hell is it?
● Patterns
● Demos
● Should it be C?
● Discussion

3. Quick Definition
● ØMQ (aka ZeroMQ, 0MQ or ZMQ)
● a high-performance asynchronous messaging library
● aimed at use in scalable distributed or concurrent
applications.
● It provides a message queue, but unlike message-oriented
middleware, a ØMQ system can run without a dedicated
message broker.
● The library is designed to have a familiar socket-style API.

4. Creators - Martin Sústrik
● Martin Sústrik (@sustrik)
● Expert in the field of messaging
middle-ware
● Participated in the creation &
implementation reference of AMQP
standard.
● Founder of the ØMQ project.
● currently is working on integration of
messaging technology with OS &
Internet stack

5. Creators - Pieter Hintjens
● Belgian software developer, writer.
● Past president of the Foundation for a Free Information
Infrastructure
● Author of Orielly ZeroMQ
● CEO or iMatix

6. Why ØMQ?
● Moore's Law means more moving pieces
● Cost of Connection is high
● Needed cheaper, fast and reliable connections
● Physics of Software Development

7. What the hell is it?
● Intelligent socket library for messaging
● Many kinds of connection patterns
● Multiplatform, multi-language (30+: ruby, C, C++, java,
python, …. )
● Fast (8M msg/sec, 30usec latency)
● Small (20K lines of C++ code)
● Distributed
● Open source LGPL (large community)

8. What the hell is it? (2)
● Socket like API. But better than sockets
● Based on reactor pattern
“Event handling pattern for handling service requests
delivered concurrently to a service handler by one or more
inputs. The service handler then demultiplexes the
incoming requests and dispatches them synchronously to
the associated request handlers.”

9. Patterns
● Request – Reply
● Publish-Subscribe
● Push-Pull (pipeline)
● Exclusive Pair

10. Request-Reply Pattern

11. Publish-Subscribe Pattern

12. Pipeline Pattern

13. Demo
● HelloWorld req-rep
● Weather pub-sub
● Tasks workers (pipeline)

14. Use Case
● Centralized Logging for rails instances
“Several application servers, consolidated logs”

15. ØMQ Transports
● Threads in one process (inproc://)
● Processes on one box (ipc://)
● Processes on one network (tcp://)
● Multicast group (pgm://)

16. ØMQ Routing
● Round-robin (REQ, PUSH, DEALER)
● Multicast (PUB)
● Fair-queuing (REP, SUB, PULL, DEALER)
● Explicit addressing (ROUTER)
● Unicast (PAIR)

17. ØMQ Benefits
● Start with simple / fast language (Python)
● Move to faster language where needed (C)
● Run on arbitrary platforms (Windows, Android)
● Scale to arbitrary sizes (2 cores, 16 cores...)
● No per-core or per-seat licensing
● Easy to experiment and learn

18. AMQP vs ØMQ
● Centralized (like SVN)
● Family of messaging
protocols used through
implementations like
RabbitMQ, Apache Qpid..
● Main use cases: transient
pubsub distribution and
reliable request-reply
● Dozens of pieces doing
perhaps a hundred
thousand messages per
second
● Distributed (like git)
● Messaging library, and
tools
● Covers transient pubsub,
unreliable request-reply,
pipeline, and peer-to-peer.
● Hundreds or thousands of
pieces perhaps doing
hundreds of millions of
messages per second

19. Why should it have been C?
● C++ was chosen for STL,
coding style, destructors,
virtual functions
● 5 years old admission:
poor choice
● Exception Handling
guarantee not failing, but
not undefined behavior
● Meant to be infrastructure
● Preventing undefined
behavior more important
● More efficient compiled
code
● System program
● Recent translation to C,
nanomsg (not released
yet)

20. References
● http://zguide.zeromq.org/page:all
● http://en.wikipedia.org/wiki/%C3%98MQ
● http://www.imatix.com/
● http://www.zeromq.org/docs:welcome-from-amqp
● http://www.rabbitmq.com/blog/tag/zeromq/
● http://www.250bpm.com/blog:4 (why it should've been C)
● http://nanomsg.org/ (C endeavor)
● http://www.zeromq.org/docs:labs
● http://www.slideshare.net/pieterh/overview-of-zeromq