[sane-devel] How to select a device?

[kenwhale]

Hi,all. I am new to SANE but I wrote some TWAIN programs before. In 
twain when multi device are connected, we can chose one we wanna do the 
scan operation. I read SANE's Document,found: there are three ways which
frontend attaching to backend,one of them is Dynamic linking.So how can 
I dynamic link to a backend??
        Thanks for any help!