zasync is a Zope 2 product that enables tasks to be done asynchronously. If your application needs to allow users to request that a long-running job be performed, but the user (and the Zope thread) shouldn't be tied up waiting for the job to complete, zasync is one possible solution. When the result of the job is ready, zasync supports both push and pull: the response can trigger TALES expressions run in the security context of the user who made the call, or the call manager can be polled to see if the response is ready.