A convenience layer atop Pika for use with RabbitMQ topic exchanges.
Project description
PikaTopic - a convenience layer atop Pika for use with RabbitMQ topic exchanges
Pika is a good general purpose library for interacting with a RabbitMQ server. PikaTopic is a simpler, limited interface which can be used when you just need to send or receive messages using a topic exchange.
Additionally, PikaTopic will handle json conversion when sending and receiving data.
See https://github.com/AnimationMentor/pikatopic for more usage examples.
Configuration
You will probably need to set the host name to connect to your RabbitMQ server. The username, password and exchange are all set to defaults which work for a generic server install.
Default values:
host is localhost OR the PIKATOPIC_HOST envariable if that is set
username is guest OR the PIKATOPIC_USERNAME envariable if that is set
password is guest OR the PIKATOPIC_PASSWORD envariable if that is set
exchange is amq.topic OR the PIKATOPIC_EXCHANGE envariable if that is set
These may be overridden by passing any of these arguments to the PikaTopic class initialiser or you can change them at the module level by:
import pikatopic pikatopic.DEFAULT_USERNAME = 'otheruser' pikatopic.DEFAULT_PASSWORD = 'secrt' pikatopic.DEFAULT_HOST = '172.17.0.2' pikatopic.DEFAULT_EXCHANGE = 'monster'
Pika Library
Pikatopic depends on the pika libary.
Examples
from pikatopic import PikaTopic
with PikaTopic(host='172.17.0.2') as pt:
pt.sendData(
"project.new",
{
'project_id':"12345-12345",
'name':"The Amazing Adventures of Sausage Farts The Dog",
'creator_id':"676867-45657",
},
)
from pikatopic import PikaTopic
def handler(routing_key, message, message_data):
if message_data:
print("%r data=%r" % (routing_key, message_data))
else:
print("%r text=%r" % (routing_key, message))
return True
with PikaTopic(host='172.17.0.2') as pt:
pt.listen(handler, ['#'])
Reference
This library provides a class, PikaTopic which can be used for sending and receiving messages.
Unless using the with construct as in the examples above, you must call open() and close() before and after the send...() and listen() functions.
Sending
sendText(routing_key (string), message (string))
sendData(routing_key (string), message (dict or list))
The sendData method converts the message to a json string and sets the message content_type property to application/json.
Receiving
listen(handler (function), binding_keys (list of strings))
The listen method enters an event loop which normally does not return.
It accepts a handler function which is called for each message received.
handler(routing_key, message_text, message_data)
message_text contains the raw text of the message. If the message is json encoded then message_data contains the decoded dict otherwise it is set to None.
If the handler returns a false value, the listen() loop will return.
Serverless Testing
Pass no_rabbit_server=True to the class initialiser to run without connecting to a server.
This might be useful for testing or transition.
You may want to also set verbose=True
Verbose
Pass verbose=True to the class initialiser to get messages sent to stdout by the listen() and send…() functions.
Thanks, Artella!
This work was funded by Artella ( https://www.artella.com/ ).
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