What is best practice to implement a long running operation in a web part.
From what I have read so far it is recommended to use PageAsyncTask or a timer which ticks once to initiate data loading.
Now I have tested PageAsyncTask and the timeout is reached after ~7 seconds in my dev environment which is not enough time for my operation. The timer way causes another problem because it fires a postback which causes an issue in combination with the project summary web part. You you can find the problem description here: New SP Timeline web part not ajax friendly!
I need to make some calls in code behind so the only way around this I can think of at the moment would be to create a web service which is then called by JS inside the web part.