I recently implemented something similar to this and it works fantastically well. In my case I use pcntl_fork() in PHP to split off a job to communicate with t

I recently implemented something similar to this and it works fantastically well. In my case I use pcntl_fork() in PHP to split off a job to communicate with the payment gateway. The parent process returns a hash to the client. The client then polls with this hash. The child process communicating with the bank will put the bank's response onto a beanstalkd tube named using this hash.