The engine_send tool can send an event file that associates channels with events. Likewise, the engine_receive tool can output an event file that includes the channel on which an event was received. The event format is the same for both tools:

For example, suppose you want to send Tick events, which contain a string followed by an integer, to the PreProcessing channel. The contents of the .evt file would look like this:

A channel name is optional. In a file being sent with the engine_send tool, you can mix event representations that specify channels with event representations that do not specify channels. Events for which a channel is specified go to only those contexts subscribed to that channel.

The default behavior is that events are sent on the default channel (the empty string) when a channel is not explicitly specified. Events sent on the default channel go to all public contexts. To change the default behavior for events sent by the engine_send tool, you can specify engine_send -c channel. If a channel is not explicitly specified for an event, then it is sent to the channel identified with the -c option . See Sending events to correlators.