Answer.

Architectural patterns are standard ways to organize interactions between system modules. The choice depends on business tasks, scaling requirements, maintenance, and development.

The most popular patterns:

• Layered — classic for separating responsibilities (presenter, service, data).
• Event-driven — event handling for loosely coupled components.
• Microkernel (plugin) — extensibility of applications (e.g., editors).

For applications with a large data flow, event and queue patterns are suitable. For example, an event is sent to a broker (RabbitMQ/Kafka), and then subscribers react asynchronously.

Example of interaction in Event-Driven architecture:

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
channel = connection.channel()
channel.queue_declare(queue='email_queue')

channel.basic_publish(exchange='', routing_key='email_queue', body='user signup event')

Key features:

• Development flexibility and ease of scaling
• Ability to use different patterns within one system (composite architecture)
• Simplicity of implementing new functions and services through events

Trick questions.

Can events only be used for asynchronous communication?

No, the event architecture allows for synchronous calls if an immediate response to an event is required.

Are layers (Layered pattern) always physically separated services?

No, layers are a logical abstraction that does not require physical separation: multiple layers can coexist in a single process.

Can the Microkernel pattern be applied only to desktop applications?

No, this pattern is also successfully applied on the server, for example, in building CMS, where modules and plugins are dynamically loaded and unloaded.