gistfile1.rb

# To set max-age
expires_in 10.minutes

# To set the etag

if stale?(:etag => @user)
# or
fresh_when(:etag => @user)

# You can also send in multiple models
if stale?(:etag => [@user, @post])

# To set last_modified 

if stale?(:last_modified => @user.updated_at.utc)
# or 
fresh_when :last_modified => @user.updated_at.utc