The adapter dispatcher calls AddSpecialParams internally after retrieving a set of parameters from an adapter (handler) and before generating an OnGetAdapterRequestParams event. This method adds parameters to the list that are not required by the adapter for handling the request.  

AddSpecialParams retrieves the Web pages that should be displayed when the adapter succeeds or fails in processing the request with which the handler is associated. If the handler has any special pages to display, AddSpecialParams adds the names of these pages to the parameters, using the parameter names of '__sp' and '__fp' (for success page and failure page), or '__p' (if the same page should be used for both success and failure). 

AHandler is the interface for the adapter associated with the action or image. 

Params is an interface that provides access to the current list of parameters. 

GetAdapterItemRequestParams 

OnGetAdapterRequestParams 

FailurePage 

SuccessPage