The transport layer is the front-end of the IAF. The transport layer's purpose is to abstract away the differences between the programming interfaces exposed by different middleware message sources and sinks. It consists of one or more custom plug-in libraries that extract downstream messages from external message sources ready for delivery to the codec layer, and send Apama events already encoded by the codec layer upstream to the external message sink. See The Integration Adapter Framework for a full introduction to transport plug-ins and the IAF's architecture.

An adapter should send events to the correlator only after its start function is called and before the stop function returns.

This topic includes the Transport Plug-in Development Specification for Java and additional information for developers of Java event transports. C/C++ Transport Plug-in Development provides analogous information about developing transport plug-ins using C/C++.