All tasks accept a url_callback and url_errback argument, that allows
to specify a HTTP endpoint that will be called when the task is complete.
This alleviates the need to poll :http:post:`/v2/status` to check if a task was completed and simplifies asynchronous code if you need to queue many tasks at once.
The callback endpoint will receive a POST containing the full task status as soon as the task ends (the same JSON that you would get on :http:post:`/v2/status`). Note that the request is not form-encoded, the POST request body contains directly the status in JSON.
Warning
If you poll :http:post:`/v2/status` just after receiving the callback, it will most likely return an "executing" status. This is expected, because it takes some time for the status to propagate to the database. This is also unneeded, since the final status is contained in the callback request body.