HTTP: Generating ETag Header

Question

How do I generate an ETag HTTP header for a resource file?

Answer 1

Ive been using Adler-32 as an html link shortener. Im not sure whether this is a good idea, but so far, I havent noticed any duplicates. It may work as a etag generator. And it should be faster then trying to hash using an encryption scheme like sha, but I havent verified this. The code I use is:

 shortlink = str(hex(zlib.adler32(link)+(2**32-1)/2))[2:-1]