50 lines
1.8 KiB
ReStructuredText
50 lines
1.8 KiB
ReStructuredText
|
Connecting to RabbitMQ with Callback-Passing Style
|
||
|
|
==================================================
|
||
|
|
|
||
|
|
When you connect to RabbitMQ with an asynchronous adapter, you are writing event
|
||
|
|
oriented code. The connection adapter will block on the IOLoop that is watching
|
||
|
|
to see when pika should read data from and write data to RabbitMQ. Because you're
|
||
|
|
now blocking on the IOLoop, you will receive callback notifications when specific
|
||
|
|
events happen.
|
||
|
|
|
||
|
|
Example Code
|
||
|
|
------------
|
||
|
|
In the example, there are three steps that take place:
|
||
|
|
|
||
|
|
1. Setup the connection to RabbitMQ
|
||
|
|
2. Start the IOLoop
|
||
|
|
3. Once connected, the on_open method will be called by Pika with a handle to
|
||
|
|
the connection. In this method, a new channel will be opened on the connection.
|
||
|
|
4. Once the channel is opened, you can do your other actions, whether they be
|
||
|
|
publishing messages, consuming messages or other RabbitMQ related activities.::
|
||
|
|
|
||
|
|
import pika
|
||
|
|
|
||
|
|
# Step #3
|
||
|
|
def on_open(connection):
|
||
|
|
connection.channel(on_channel_open)
|
||
|
|
|
||
|
|
# Step #4
|
||
|
|
def on_channel_open(channel):
|
||
|
|
channel.basic_publish('exchange_name',
|
||
|
|
'routing_key',
|
||
|
|
'Test Message',
|
||
|
|
pika.BasicProperties(content_type='text/plain',
|
||
|
|
type='example'))
|
||
|
|
|
||
|
|
# Step #1: Connect to RabbitMQ
|
||
|
|
connection = pika.SelectConnection(on_open_callback=on_open)
|
||
|
|
|
||
|
|
try:
|
||
|
|
# Step #2 - Block on the IOLoop
|
||
|
|
connection.ioloop.start()
|
||
|
|
|
||
|
|
# Catch a Keyboard Interrupt to make sure that the connection is closed cleanly
|
||
|
|
except KeyboardInterrupt:
|
||
|
|
|
||
|
|
# Gracefully close the connection
|
||
|
|
connection.close()
|
||
|
|
|
||
|
|
# Start the IOLoop again so Pika can communicate, it will stop on its own when the connection is closed
|
||
|
|
connection.ioloop.start()
|