How do I return data from a deferred task in Google App Engine

Question

Original Question

I have a working version of my web application that I am trying to upgrade at the moment, and I\'m running into the issue of having a task which

Answer 1

Normally you can't reply to the original request anymore since the context of that original request dissapears. Maybe, if you return from the request handler without replying and if somehow that doesn't kill the connection from the client and if you are somehow able to persist the handler object so that you can later restore it in another (internal) request and use the restored copy to reply from it to the original request... Kind of a long shot at best.

One option would be to split the operation into a sequence: - a 1st request starting the operation - subsequent one or more polling requests until the operation completes and the result is available

Another approach may be possible if the expensive operation is mainly executing on data available prior to when the operation is invoked. You could re-org the app logic so that partial results are computed as soon as the respective data becomes available, so that when the final operation is requested it only operates on pre-computed partial results. An analogy, if you want, would be Google search requests immediately receiving replies with data from pre-computed indexes instead of waiting for an actual web search to be performed.