twingly-pyamqp 0.2.3

A Python implementation for subscribing and publishing messages via RabbitMQ.

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

Argument	Type	Default	Description
exchange_name	str | None	None	The name of the exchange to route the messages to. Leave empty to publish to default exchange.
routing_key	str | None	None	The routing key used for directing the message.
config	AMQPconfig | None	None	Optional override configuration for AMQP connection settings.
publish_args	dict | None	None	Additional arguments that match the publish method arguments of Kombu's Producer.
exchange_opts	dict | None	None	Exchange options.
max_retries	int | None	None	Number of attempts to reconnect and publish.
compress_fields	list[str] | None	None	List of fields to compress before publishing.
compression_level	int | None	None	level is the compression level – an integer from 0 to 9 or -1. A value of 1 (Z_BEST_SPEED) is fastest and produces the least compression, while a value of 9 (Z_BEST_COMPRESSION) is slowest and produces the most.

Methods

publish

Argument	Type	Default	Description
payload	object	No	The message to publish to the exchange.
routing_key	str | None	None	Optionally override the default routing key.
publish_args	dict | None	None	Additional publishing arguments.

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})

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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].

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Subscription

Arguments

Constructor

Argument	Type	Default	Description
queue_names	str | list[str]	No	The name of the queue(s) to subscribe to. Accepts a single name or a list.
config	AMQPconfig | None	None	Optional override configuration for AMQP connection settings.
exchange_name	str | None	None	Name of Exchange
bindings	dict[str, list[str]] | None	None	Bind Exchange to Queue, dict queue name keys and a list of routing keys.
queue_opts	dict | None	None	Optional queue options such as Durable, etc.
exchange_opts	dict | None	None	Optional exchange options
heartbeat	int	30	Hearbeat to check the connection.
compressed_fields	list[str] | None	None	Optional list of fields to decompress when receiving messages.

Methods

subscribe

Argument	Type	Default	Description
callbacks	Callable[[str, object], None] | list[Callable[[str, object], None]]	No	The function(s) to process incoming messages.
blocking	bool	True	If True, blocks the main thread while consuming messages.
consumer_args	dict | None	None	Additional arguments that match Kombu's Consumer arguments.

Raises RuntimeError if a subscription is already active.

cancel

Argument	Type	Default	Description
None	-	-	Cancels the active subscription and stops consuming messages.

purge_queue

Argument	Type	Default	Description
queue_name	str	-	Name of queue to purge

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.