This question sort of extends my other question on robots and captcha. I did what everyone recommend (thanks everyone!), however is it at all possible to detect a robot on the server first? For Example (Once again, I will use Stackoverflow as a reference): Sometimes when I ask a question, Stackoverflow comes back asking me to verify if I am human.
However, sometimes it does not.
How does Stackoverflow do that, because that is what I want to do: Check data and if it looks like a robot, request human verification.
Also this needs to be done on Java (preferably), Perl or PHP.
On StackOverflow, it’s done by performing the same task too many times too quickly or performing multiple tasks too quickly.
If you want to emulate this, you can keep track of the number and time(s) of recent requests and check to see that everything is within your limits. If it isn’t, redirect to a CAPTCHA.
Unfortunately, I don’t have enough Java EE experience to provide any code, but hopefully my approach will give you some idea(s).