Twingly::PYAMQP

A Python implementation of the twingly-amqp gem for subscribing and publishing messages via RabbitMQ.

Usage

Environment variables:

• RABBITMQ_N_HOST - Defaults to localhost
• AMQP_USERNAME - Defaults to guest
• AMQP_PASSWORD - Defaults to guest

Docs

AMQPconfig

Used to configure RabbitMQ host, port, user, password, and ssl. Arguments take precedence over environment variables and should only be used to override environment or default values, since env variables and default values are used if no AMQPconfig is provided.

Arguments

• rabbitmq_host
• rabbitmq_port
• amqp_user
• amqp_password
• ssl

Publisher

Arguments

Constructor

Methods

publish

Example Usage

# Create an instance of Publisher with default values
publisher = Publisher(compress_fields=["payload"])

# Create an instance of Publisher with a specific routing key
publisher = Publisher(exchange_name="custom_exchange", routing_key="custom_routing_key")

# Publish messages
publisher.publish({"message": "hello, RabbitMQ"})  # Uses the routing key specified at instantiation
publisher.publish({"message": "hello, RabbitMQ"}, routing_key="override_routing_key") # Overrides routing key

# Publish message with additional arguments
publisher.publish({"message": "hello, RabbitMQ"}, publish_args={"priority": 7})

Compression

The Publisher class supports compressing specified fields in the message payload using zlib compression. This is particularly useful for reducing the size of large text fields before sending them over the network.

Limitations

• Only fields of type str are supported for compression. Attempting to compress fields of other types will raise a TypeError.
• The payload must be an indexable object (like a dictionary) for compression to work, as fields are accessed via payload[field].

Subscription

Arguments

Constructor

Methods

subscribe

Raises RuntimeError if a subscription is already active.

cancel

purge_queue

Example Usage

# Create an instance of Subscription for a single queue
subscription = Subscription(queue_names="task_queue")

# Create an instance of Subscription for multiple queues
subscription = Subscription(queue_names=["queue1", "queue2"])

# Subscribe to messages in blocking mode
subscription.subscribe(callback=Callable[[str, object], None])

# Subscribe to messages in non-blocking mode with a timeout
subscription.subscribe(callback=Callable[[str, object], None], blocking=False, timeout=5,consumer_args={"no_ack": True, "prefetch_count": 5})

# Cancel the subscription
subscription.cancel()

Decompression

The Subscription class supports decompressing specified fields in incoming message payloads that were previously compressed using zlib compression. If a message contains compressed_fields in its headers, those fields will be decompressed upon receipt. The user can also specify a default list of fields to decompress when initializing the Subscription instance.