MSDN Documentation

1. Direct API Calls

The simplest integration pattern involves making direct HTTP requests from your application to the API endpoint. This is often suitable for straightforward integrations where latency and real-time data are critical.

Pros:

• Simplicity and ease of implementation.
• Low latency for immediate data retrieval.
• Suitable for stateless interactions.

Cons:

• Can lead to tight coupling between systems.
• Error handling and retry mechanisms need to be managed in the client.
• Scalability can be an issue if the client needs to handle many concurrent requests.

Example (Conceptual):

POST /api/v1/users HTTP/1.1
Host: api.example.com
Content-Type: application/json
Authorization: Bearer YOUR_ACCESS_TOKEN

{
  "name": "Jane Doe",
  "email": "jane.doe@example.com"
}
                

2. Publish/Subscribe (Pub/Sub)

The Publish/Subscribe pattern decouples message producers from message consumers. Producers publish messages to a topic, and consumers subscribe to topics they are interested in. This is ideal for event-driven architectures and asynchronous communication.

Key Components:

• Publisher: An application that sends messages.
• Subscriber: An application that receives messages.
• Topic/Channel: A named logical channel to which messages are published.
• Broker/Message Queue: A middleware that routes messages from publishers to subscribers.

Benefits:

• High decoupling between services.
• Enables asynchronous processing.
• Scalable and fault-tolerant.

Use Cases:

• Real-time notifications.
• Event sourcing.
• Distributing tasks across multiple workers.

3. API Gateway

An API Gateway acts as a single entry point for multiple backend services. It handles concerns such as authentication, authorization, rate limiting, request routing, and response transformation, simplifying client interactions and enhancing security.

Functions:

• Centralized Authentication/Authorization: Enforces security policies.
• Request Routing: Directs requests to appropriate backend services.
• Rate Limiting: Protects backend services from overload.
• Response Aggregation: Combines responses from multiple services.
• Protocol Translation: Can translate between different protocols.

Advantages:

• Simplifies client-side logic.
• Improves security and manageability.
• Enables easier evolution of backend services.

4. Backend for Frontend (BFF)

This pattern involves creating dedicated backend services tailored to the specific needs of different frontend applications (e.g., web, mobile, IoT). Each BFF aggregates and transforms data from various microservices to optimize the experience for its respective client.

Rationale:

• Addresses diverse frontend requirements (data formats, performance).
• Reduces overhead on individual frontend applications.
• Allows frontends to evolve independently.

Benefits:

• Optimized performance for each client type.
• Simplified frontend development.
• Independent evolution of frontends and backends.

5. Webhooks

Webhooks are automated messages sent from apps when something happens. They are a way for an application to provide other applications with real-time information as it occurs. When an event occurs in the source system, it sends an HTTP POST request to a pre-configured URL (the webhook URL) in the destination system.

How it works:

1. An event occurs in the source system (e.g., a new order is placed).
2. The source system sends an HTTP POST request containing event data to a specified webhook URL.
3. The destination system receives the request and processes the event.

Advantages:

• Real-time data synchronization.
• Reduces the need for constant polling.
• Efficient for event-driven updates.