ContentsHandler

This callback is used to generate custom contents published with the add_handler function.

The arguments passed are the same as passed to add_handler. The Publisher will decrease the reference count of the returned buffer after deliving it. It's valid to return null in situations were no contents can be generated.

Parameters:

publisher	the Publisher
key	the unique key
user_data	user data set when the signal handler was installed

Returns:

The Contents buffer for this publication, or null .