i have implemented getting thumbnail file/folder preview using an http request in v4.

sending an http request to a catalyst host at 192.168.0.5-
http://192.168.0.5:8080/catws/Images/000_001.jpg

will get you a thumbnail of folder 000 file 001

to get other files change the file name

for example folder 5 file 10

http://192.168.0.5:8080/catws/Images/005_010.jpg