The categories below list KB articles with examples posting a response in an HTTP Listener channel: Note: qie.postMessageResponse() is not specific to HTTP Listener source nodes:
What source nodes does qie.postMessageResponse apply to?
Responding to requests with HTTP status codes
How do I set the 'Content-Type' in an HTTP Response?
The KB articles linked above all contain examples of returning a response using qie.postMessageResponse() where the response was built using the string data type (as text). Here are a couple more examples.
How can I post a response in a mapping node?
How can I configure a ProviderAndRegisterDocumentSet endpoint to listen for incoming messages ?
What html code can be used in QIE to redirect to a different URL.
See also:
Handling HTTP requests and responses