Anti-Corruption Layer Pattern

Introduction

The Anti-Corruption Layer (ACL) pattern is an architectural pattern that serves as a barrier between two systems, allowing them to communicate without compromising each other’s integrity. It ensures that the internal model of one system is not affected by the external model of another, thus preventing corruption of the domain model.

Definition

The Anti-Corruption Layer is a design pattern that enables application A to communicate with application B without exposing application A's internal model to the external system, thereby protecting it from external changes and corruption.

Key Concepts

• Isolation: Keeping the internal domain model separate from external systems.
• Translation: Converting data formats between systems.
• Adaptation: Adapting the behavior of one system to fit the expectations of another.

Workflow

            graph TD;
                A[Application A] -->|Request| B[Anti-Corruption Layer];
                B -->|Transform| C[Application B];
                C -->|Response| B;
                B -->|Return| A;
            

This flowchart illustrates how Application A interacts with Application B through the Anti-Corruption Layer.

Implementation

Here’s a simple example in Python illustrating how an Anti-Corruption Layer can be implemented:

class ExternalService:
    def fetch_data(self):
        return {"data": "value_from_external_service"}

class AntiCorruptionLayer:
    def __init__(self, external_service):
        self.external_service = external_service

    def get_data(self):
        external_data = self.external_service.fetch_data()
        return self.translate_data(external_data)

    def translate_data(self, external_data):
        return {"internal_format": external_data["data"]}

# Usage
external_service = ExternalService()
acl = AntiCorruptionLayer(external_service)
data = acl.get_data()
print(data)  # Output: {'internal_format': 'value_from_external_service'}
                

This code demonstrates how to use an ACL to fetch and translate data from an external service into an internal format.

Best Practices

• Keep the ACL small and focused on translating data.
• Use clear interfaces to define interactions between the ACL and external services.
• Ensure you have thorough unit tests to validate the behavior of the ACL.

FAQ