Release 10.1A: OpenEdge Getting Started:
OpenEdge Reference Architecture

Loosely coupled integration model

The loosely coupled integration model is based on asynchronous messaging. There is no direct binding that connects one application to another. Some sort of intermediary process, serving as a message broker, relays information from one application to another.

Messaging provides a great deal of flexibility from a design standpoint. The ability to communicate using standard protocols (TCP/IP, HTTP, etc.) allows for a simpler design of Integration Layer components to support the integration model.

A loosely coupled design typically uses a set of standard messaging protocols to manage messages being sent through the message broker. All participating applications must agree on these standards.