First of all you can not switch portlet views using async commands, you have to use regular command buttons/links to do it.
Second if you pass in control parameters in the command then in the target view you can access them via following binding expression:
“#{param[‘param_name’]}”
This is a valid way of passing parameters, but keep in mind that there parameters are transient and any subsequent request you make will erase them so you need to capture and store them in the page bean.
From this point it can make sense to have just java properties declared on your page bean (or on some other managed bean you may define just for this purpose) and use hidden inputs to submit values bound to these properties when command is invoked. Then you can easily access them from any view.
#webMethods-BPMS#webMethods#MWS-CAF-Task-Engine