AppInstall remote event is called multiple times

Question

When developing provider hosted apps and testing in SharePoint Online, I've noticed that my AppInstalled remote event is often triggered 4 times when installing the app in site content. Here is an except from a log:

[07:47:38] ProcessEvent: AppInstalled
[07:47:54] ProcessEvent: AppInstalled
[07:48:04] ProcessEvent: AppInstalled
[07:48:10] ProcessEvent: AppInstalled

I suspect SPO thinks the installation somehow failed and therefore trying attempting to install it again. How can I stop this from happening? I tried using clientContext.RequestTimeout = Timeout.Infinite without success

Answer 1

I have yet to find any good solution to this problem. Some suggest intercepting events and cancel/halt them until the first call is finished. While I was able to use this technique while developing, it causes other problems though, especially with communicating back to SharePoint if the app was properly installed or not. Thus I do not find it an acceptable solution for production.

I decided to remedy the situation by moving the (time expensive) provisioning code from the AppInstall event into a button on the App's page. The user will first have to install the app, then open the app and manually click the button to complete the installation. From a user experience point of view this is not as good, but it seems to be the most proper way to do this for now.

Answer 2

You are correct that SP will retry 4 times if it fails to install/upgrade/uninstall. Have you checked to see if there are any errors being thrown from your Remote Event? There could be errors in generating ClientContext? A snippet of the code will help to diagnose?

If you do have errors, ensure you set the ErrorMessage and Status of the SPRemoteEventResult result = new SPRemoteEventResult(); before returning to SharePoint.

You can also propagate errors to the App Details page using the following code:

Microsoft.SharePoint.Client.Utilities.Utility.LogCustomRemoteAppError(ctx, productId, messageToLog);
ctx.ExecuteQuery();