Question

I am designing the architecture for a module where a search takes place.
the search takes some time, and I would like to have the UI to be responsive, so I get to delegate the retrieval of the data to a class that will do the search on a separate thread.

Then, I can think of two options :

either
1° : the search method returns a viewmodel with empty data as a return value (place holder), but once the search process is over, the viewmodel’s members will be updated and the result displayed on screen thanks to data binding,

2° : the search method doesn’t have any return type, but once the search process is over, an event is raised and the viewmodel with its final values is passed in the event args so it can be used by the calling code. (and eventually be consumed by a view)

Any thoughts on this one ?

EDIT: Of course, with solution 1° I’m refering to WPF databinding on the objects returned by the search-results “place-holder” objects

Answer 1

I’d take advantage of data binding and bind your search result presentation control to a observable collection of search results and update that collection in your ViewModel from a background worker thread. Then it doesn’t required any callbacks or update messages in you code, it just works as you’d expect taking advantage of the plumbing in place in WPF.