Trigger components are a type of components which may receive data from an external system. Once data is received the data will simply be forwarded to the rest of the pipeline.
Examples of trigger components are:
* http trigger; this receives messages using http (using TLS).
* Ethereum trigger; this receives events from a blockchain node.
What they components have in common is that they do not do anything with the data, but just store it in the pipeline state object.