reports can be initiated from the QlikView applciation through the NPrinting on-demand functionality
there are nprinting client extensions that need to be added to the applciation that allow the user to initiate an nprinting report or task.
Here are some nprinting on demand articles but please refer to the website for further info
I would also suggest downloading the nprinting training environment as well - it has actual applications and working examples that are extremely helpful
also refer to the reference inforamtion on the NPrinting community, located at Qlik NPrinting