Overview the communication architecture design in a famous cloud platform via high level system analysis.

1. Communication Framework
in
OpenStack
Sean Chang
2014/12

2. Overview of OpenStack commnication
My OpenStack environment
OpenStack communication architecture
AMQP
RabbitMQ
kombu
How to debug

3. Three nodes for OpenStack
Nodes(mgm. ip)
control(10.10.10.21)
NTP, RabbitMQ, MySQL,
Keystone, Glance,
Neutron, Nova, Cinder,
Heat, and Horizon
network(10.10.10.22)
NTP and Neutron
compute(10.10.10.23)
NTP, Nova, and Neutron

4. Communication Flow

5. Neutron
Messaging in Openstack using RabbitMQ
( Queue–server)

6. AMQP

7. MQ support
Supporting list
RabbitMQ(default in JUNO)
Qpid
ZeroMQ(non-AMQP)

8. ●The Advanced Message Queuing Protocol (AMQP) is
an open standard for passing business messages
between applications or organizations.
● AMQP was designed with the following main
characteristics as goals:
○ Security
○ Reliability
○ Interoperability
○ Standard
○ Open
AMQP

9. AMQP Product and Success Stories
A standard is no use without products, and there are is a choice of
excellent AMQP technology suppliers.
Apache Qpid, an Apache project
Microsoft's Windows Azure Service Bus
JBoss A-MQ by Red Hat built from Qpid
StormMQ a cloud hosted messaging service based on AMQP
VMware Inc RabbitMQ; also supported by SpringSource
...
OpenStack
OpenStack is an open-source initiative that provides a massively scalable cloud operating
system and uses RabbitMQ for messaging.

10. Why does OpenStack use AMQP
Consider design and scalability
Loose coupling between client and server side
Asynchronize is available
Load balance could be inactive

11. RabbitMQ
You may be thinking of data delivery, non-blocking operations or push
notifications. Or you want to use publish / subscribe, asynchronous
processing, or work queues. All these are patterns, and they form
part of messaging.
RabbitMQ is a messaging broker - an intermediary for messaging. It
gives your applications a common platform to send and receive
messages, and your messages a safe place to live until received.

12. kombu
kombu - Messaging library for Python
Kombu is a messaging library for Python.
The aim of Kombu is to make messaging in Python as easy as possible by providing an
idiomatic high-level interface for the AMQ protocol, and also provide proven and tested
solutions to common messaging problems.
AMQP is the Advanced Message Queuing Protocol, an open standard protocol for message
orientation, queuing, routing, reliability and security, for which the RabbitMQmessaging
server is the most popular implementation.

13. 重點提要
雖然網路上有關AMQP、RabbitMQ、kombu的
資料不計其數，但真正OpenStack在實作上
應用範圍看下面幾頁就夠了
了解太多反而會失去方向

14. The internals elements of a message broker
node

15. Internals elements relationship
Producers
Producers sends messages to an exchange.
Exchanges
Messages are sent to exchanges. Exchanges are named and can be
configured to use one of several routing algorithms. The exchange routes
the messages to consumers by matching the routing key in the message
with the routing key the consumer provides when binding to the
exchange.
Consumers
Consumers declares a queue, binds it to a exchange and receives messages
from it.
Queues
Queues receive messages sent to exchanges. The queues are declared by
consumers.

16. Routing keys
Every message has a routing key. The interpretation of the routing key depends on the exchange type.
There are four default exchange types defined by the AMQP standard, and vendors can define
custom types (so see your vendors manual for details).
These are the default exchange types defined by AMQP/0.8:
Direct exchange
Matches if the routing key property of the message and the routing_key attribute of the
consumer are identical.
Fan-out exchange
Always matches, even if the binding does not have a routing key.
Topic exchange
Matches the routing key property of the message by a primitive pattern matching scheme. The
message routing key then consists of words separated by dots (”.”, like domain names),
and two special characters are available; star (“*”) and hash (“#”). The star matches any
word, and the hash matches zero or more words. For example “*.stock.#” matches the
routing keys “usd.stock” and “eur.stock.db” but not “stock.nasdaq”.
The exchange types(define by AMQP)

17. RPC Casts

18. RPC Calls

19. How to debug
command line
rabbitmqctl [-n node] [-q] {command} [command
options...]

20. How to debug
Management Plugin
The rabbitmq-management plugin
provides an HTTP-based API
for management and monitoring
of your RabbitMQ server, along
with a browser-based UI and a
command line tool,
rabbitmqadmin.
Web UI
http://server-name:15672/
default account/passwd：
guest/guest

21. 心得
docs.openstack.org就是很好的學習出發點，
不管是整體概念、系統架構、設計說明、程
式碼說明；其他資料如lib docs、網路文件、
甚至是openstack source code當作真的看不
懂再去找就可以，避免繞遠路。
小心見林不見樹、見樹不見林

22. Q & A