Häufige Fehler und Anti-Patterns

In software design, an anti-pattern describes a common response to a recurring problem that is usually ineffective and may even be counterproductive.

In microservices, anti-patterns can lead to systems that are hard to maintain, scale, and debug. Learning to identify and avoid them is crucial for building robust distributed systems.

One of the most common pitfalls is creating a distributed monolith. This happens when you break down a monolithic application into separate services, but they remain tightly coupled.

Instead of one big application, you now have several small applications that still behave like one, requiring coordinated deployments and sharing too much internal logic or data.

How can you tell if your services are too coupled?

• Shared Database: Services directly access another service's database.
• Synchronous Chains: A single request requires multiple synchronous calls across several services.
• Deployment Dependencies: Services must be deployed in a specific order or simultaneously.
• Breaking Changes: A small change in one service breaks others unexpectedly.

To avoid a distributed monolith, focus on:

• Data Ownership: Each service should own its data and expose it only via its API.
• Asynchronous Communication: Prefer event-driven communication (message queues) over direct synchronous calls.
• Well-Defined APIs: Use clear, versioned APIs to minimize dependencies between services.

Another anti-pattern is chatty communication. This occurs when services exchange too many small, frequent messages to complete a single task, often requiring multiple round trips.

Imagine a client needing user details, order history, and product preferences, and having to make three separate calls to three different services.

Chatty services introduce significant overhead:

• Increased Latency: Each network hop adds delay.
• Higher Resource Use: More connections, more CPU for serialization/deserialization.
• Complex Error Handling: More points of failure to manage.

Solution: Design APIs to return richer data, use API Gateways for aggregation, or batch requests where possible.

In distributed systems, operations can sometimes be executed multiple times due to network retries or message duplication. If an operation isn't idempotent, these retries can lead to unintended side effects.

An idempotent operation produces the same result whether it's called once or many times with the same inputs.

Consider a payment service. If a charge operation isn't idempotent, retrying it could charge the customer multiple times. See how a simple operation can cause issues:

Another pitfall is over-engineering. This means applying complex patterns (like a full Saga orchestration) when simpler solutions (like a direct database transaction or a basic retry) would suffice.

Start with the simplest viable solution. Introduce complexity and advanced patterns only when the problem truly demands it, and your understanding of the trade-offs is clear.

We've explored several common pitfalls and anti-patterns in microservices communication:

• The Distributed Monolith due to tight coupling.
• Chatty Services causing latency and overhead.
• Ignoring Idempotency, leading to unintended side effects.
• Over-engineering with complex patterns unnecessarily.

By understanding and avoiding these, you can build more resilient, scalable, and maintainable microservices architectures.