The customary way is to write to a file that is monitored by the forwarder. The forwarder to pick up whatever is written to the file and send it to the indexer(s).
Right, but let's say you have a heavy duty app. Can it write to memory and the forwarder will pick it up? It's interesting as in the admin course material they show the Deployment Client as a pluggable module. So, conceivably, the deployment can be customized.
I know of no memory interface to the forwarders.