AMQP Internal Library

Internal library for exchanging messages between services instantiated in the AWS environment. The base used for the elaboration of the package was the PIKA library developed by the RabbitMQ team.

Installation

To use the library it is necessary to have Python3 installed on the machine and run the following command:

python3 -m pip install cosecurity-amqp-lib

Environment Variables File

• AMQP_USER user for connecting to RabbitMQ
• AMQP_PASSWORD password for connecting to RabbitMQ
• [SERVICE_NAME] service name and respective service queue name, can be more than one
• AMQP_SOCKET_TIMEOUT socket connect timeout in seconds
• AMQP_HEARTBEAT AMQP connection heartbeat timeout value for negotiation during connection tuning or callable which is invoked during connection tuning

if it is a local instance:

• AMQP_HOST host to connect to RabbitMQ, if localhost does not need to fill the port

if the connection is via Amazon MQ:

• AMQP_BROKER_ID amqp id inside aws
• AWS_REGION region where amqp is allocated within aws

Consumers

Consumers are instances that monitor a specific queue, and if there is a change in the queue, they perform a certain action.
In this library a consumer can have more than one action/method, called primitive. In addition, each action will still have its default input set. Each method that must be an action must be registered so that it can be triggered if there is a change in the directed queue.
Below is an example of how to create a consumer class:

from typing import Any, Dict
from cosecurity_amqp_lib.consumer import Consumer

class ConsumerExample(Consumer):
    def __init__(self) -> None:
        super().__init__(
            name='example'
        )
        self.register(self.primitive_one)
        self.register(self.primitive_two)
        self.start()
    
    def primitive_one(self, content:Dict[str, Any]) -> None:
        print(content['hello'])
    
    def primitive_two(self, content:Dict[str, Any]) -> None:
        print(content['message'])

Producers

Producers are responsible for producing and/or posting new messages in consumer queues.
In the internal library the producers are called stub, I try their methods defined and typed based on what has already been defined as primitive in their consumer.
Below is an example of how to create a stub inside the library in the stub.py file:

class ExampleStub(Stub):
    def __init__(self):
        super().__init__(
            destination='example'
        )

    def primitive_one(self) -> None:
        self._send(
            primitive='primitive_one',  
            content={
                'hello': 'word'
            }
        )

    def primitive_two(self, message:str) -> None:
        self._send(
            primitive='primitive_two',  
            content={
                'message': message
            }
        )

Now, an example of how to use an already created stub and publish it in the library in Pypi:

from cosecurity_amqp_lib.stub import ExampleStub

example_stub = ExampleStub()
example_stub.primitive_one()
example_stub.primitive_two(message='Hello world!')

Additional arguments for queues

In the creation of the consumers it is possible to pass some additional configurations for the creation of the queue, these configurations can be found on the official RabbitMQ website. Below is a representation of how to pass an additional argument:

class ConsumerExample(Consumer):
    def __init__(self) -> None:
        [...]
        self.start(
            arguments={
                'x-queue-mode': 'lazy'
            }
        )

Example

In the example/simple folder we have a real case example of a stub sending an string to a consumer.