Question

I have a Google App Engine application that performs about 30-50 calls to a remote API. Each call takes about a second, so the whole operation can easily take a minute. Currently, I do this in a loop inside the post() function of my site, so the response isn’t printed until the whole operation completes. Needless to say, the app isn’t very usable at the moment.

What I would like to do is to print the response immediately after the operation is started, and then update it as each individual API call completes. How would I achieve this? On a desktop application, I would just kick off a worker thread that would periodically update the front-end. Is there a similar mechanism in the Google App Engine?

I googled around for “progress bar” and “google app engine” but most results are from people that want to monitor the progress of uploading a file. My situation is different: the time-consuming task is being performed on the server, so there isn’t much the client can do to monitor its progress. This guy is the closest thing I could find, but he works in Java.

Answer 1

1. Send the post logic to a task using http://code.google.com/appengine/docs/python/taskqueue
2. Change the logic of the process to set a status (it could be using memcache)
3. Using AJAX query memcache status each 10 seconds, more or less, it’s up to you