ZeroMQ as scriptable sockets

transcript

Bear Metal OÜ| Õismäe tee 78-25, 13513 Tallinn, Harjumaa, Estonia | info@bearmetal.eu

Realtimeconf EU 2013Lyon - http://realtimeconf.eu/

Lourens Naudé

Monday, April 22, 13

Why this talk ?

Operations / Platform

Credentials

ZeroMQ monitoring supportczmq co-maintainerRuby bindingExperimental TLS support

99% of deployments don’t need enterprise

reliability

Of reliability

Then ...

... now

Zero broker, admin, cost, waste, price tag and (almost) zero latency

What is ZeroMQ ?

What it isn’t

IM for apps

Not a server or message queueA libraryCommunication / concurrencyMessaging semantics for sockets

BSD API

sock.bind(“inproc://workers”)sock.connect (“tcp://0.0.0.0:30”)sock.send (“message”)msg = sock.recv ()sock.close ()

Community

30+ language bindings ...

Super (scriptable) sockets

What is a ZeroMQ socket ?

bind () or connect () to multiple endpoints,

simultaneously

Multiple endpoints

bind () or connect () in any order

Async connect

Socket types

PUB SUB

REQ REP

PUSH PULL

Request / reply

REP REP

REQ REQ

Request / Reply usage

Lock stepBi-directionalRoutableFlow control, orchestration etc.

Publish / subscribe

SUB SUB SUB

Inversion - logging

PUB PUB PUB

Publish / subscribe usage

Market data, game state etc.PUB socket distributesSUB socket filtersSubscription forwarding (3.x)

Pipeline

PULL PULL PULL

Pipeline usage

Extendable - UNIX pipesRound-robin distributionTasks with variable processing

Transport agnostic

inproc:// - threads in a processipc:// - processes on a boxtcp:// - nodes in a networkUniform API

Lightweight switchesDevices

pub/sub persistence

PERSISTENCEDEVICE

Device main loop

loop do m = sub_socket.recv () persist (m) pub_socket.send (m)end

Use cases

ProxyRouting (LRU)Filtering / de-dupTranslation

Work distribution

VENTILATOR

PULLBear Metal OÜ| Õismäe tee 78-25, 13513 Tallinn, Harjumaa, Estonia | info@bearmetal.eu

Scalable work distribution

Interjection Principle

Scalable topologies

Saving bandwidth

SUBPUB

SUB SUB

Asynchronous external dependencies.

Resiliency

Atomicity

Atomic message deliveryUnbound message sizeSend 5GB, recv all or nothing

Availability

Delayed retry on failureMulti bind() and connect()Unordered bind() or connect()

Reliability as patterns

Lazy Pirate (REQ / REP)Majordomo (queue)Titanic (persistence)Binary Star (High Availability)See http://zguide.zeromq.org

ZeroMQ concurrency

PULL PULL PULL

MAIN THREAD

THREAD 1 THREAD 2 THREAD 3

I/OTHREAD

s = ctx.bind(:PUSH, "inproc://w")3.times{ spawn_worker(ctx) }loop do msg = work.shift break if msg == “exit” s.send(msg)end

Master (work distributor)

Thread.new do s = ctx.connect(:PULL, “inproc://w”) loop do msg = s.recv break if msg == "quit" process(msg) endend

Workers (consumer threads)

Mongrel2Case study

How it works

Multi-protocolZeroMQ for backendsAsync backend requestsLanguage agnostic (bindings)

Mongrel2 topology

BACKEND A BACKEND B

MONGREL2

CLIENT

Mongrel2 protocol

UUID ID PATH SIZE:HEADERS,SIZE:BODY

Mongrel2 HTTP request

PUSH PULL

AB23 4 /uri SIZE:HEADERS,SIZE:BODY

Mongrel2 HTTP response

SUB PUB

AB23 4 /uri SIZE:HEADERS,SIZE:BODY

Questions ?(... or sync up after)

fork @methodmissingfollow @methodmissing

ZeroMQ as scriptable sockets

Technology