Pass-through Coupling

Definition#

Pass-through coupling refers to a situation where one service acts as an intermediary between two services. It accepts data from one service and passes it to another service without using it or doing any modification on it.

This type of coupling can create unnecessary dependencies and complexity in the system, as it introduces additional layer that do not contribute to meaningful functionality but requires the changes if the data structure changes.

Example#

Suppose in an order management system,

• Order Service sends shipment details along with order items to the Inventory Service.
• Inventory Service reduces the inventory stock based on the order items.
• Inventory Service then passes the shipment details to the Delivery Service.