adr-004-async-messaging.md

ADR 004: Asynchronous Inter-Module Communication

Status

Accepted

Context

We need a way for modules to communicate asynchronously for eventually consistent operations.

Decision

We will use a message bus for asynchronous inter-module communication.

Consequences

Positive

• Decouples modules
• Supports eventual consistency
• Improves scalability

Negative

• Increased complexity
• Potential for message failures

Example

public class OrderCreatedMessage : IMessage
{
    public string OrderId { get; set; }
    public string ProductId { get; set; }
    public int Quantity { get; set; }
}

// In the Order module
await _messageBroker.PublishAsync(new OrderCreatedMessage { ... });

// In the Inventory module
public class OrderCreatedMessageHandler : IMessageHandler<OrderCreatedMessage>
{
    public Task Handle(OrderCreatedMessage message, CancellationToken cancellationToken)
    {
        // Update inventory
    }
}

This allows for asynchronous communication between the distinct modules.