Get Notification of folder change in Personal OneDrive using Xamarin CrossPlatform & Graph

Universal Camera 276

I have a Xamarin Forms CrossPlatform working App using Graph LargeFile tutorial

var fileUploadTask = new LargeFileUploadTask<DriveItem>(uploadSession, stream, maxSliceSize);

I would like to add folder change notification from OneDrive. I have looked at documentation for Graph WebHook but have not been able to run the sample provided.

Since I already have the Token to get DriveItem, Graph documentation states that I should be able to get from OneDrive notification when a file is deleted from a folder.

Can someone tell me what can I do to get the notification from OneDrive when a <DriveItem> file is deleted.

Thanks in advance!

Kyle Wang 5,531 Reputation points Microsoft Vendor

2021-07-05T09:41:00.5+00:00

@Universal Camera About monitoring changes in OneDrive, you can refer to this document. And here is a demo how to use Microsoft Graph in Xamarin.
Universal Camera 276 Reputation points

2021-07-12T18:17:50.65+00:00

I studied your references which are the same I studied before I posted the question.

I already have the proper scopes defined to read/write/delete a DriveItem file. I am able to do all that I defined in the scope successfully with my CrossPlatform App.

Since I don't understand the documentation and download sample are not working could you please help in clarifying how OneDrive can notify my App when one of the DriveItem file is deleted by the user in the OneDrive.

Thank You!
Kyle Wang 5,531 Reputation points Microsoft Vendor

2021-07-13T09:43:44.307+00:00

@Universal Camera Microsoft Graph REST API will deliver change notifications to clients which is a web service. So the first you need to do is creating web service for Xamarin.Forms. As to subscribe to notification, you can refer to the tutorial:Use Change Notifications and Track Changes with Microsoft Graph.
Universal Camera 276 Reputation points

2021-07-19T22:42:04.493+00:00

thank you!

Clarification...
In the tutorial they use Visual Code to develop REST based codes.

BUT I am adapting OneDrive/graph-sample-photobrowser-uwp example to upload/download data. This example is not REST based. It works very good!

Does this mean I cannot use my current code. I mean I have the Token and DriveItem and Scopes...Everything is known. How can I implement notifications from OneDrive in my current strategy.
Kyle Wang 5,531 Reputation points Microsoft Vendor

2021-07-20T09:44:48.393+00:00

@Universal Camera That demo only achieve downloading data from OneDrive, but if you want to implement "Notification", you need "Webhook" to "call back".
Universal Camera 276 Reputation points

2021-07-20T14:18:03.923+00:00

perhaps wrong choice of word "Notification"

I want to know if a OneDrive file in DriveItem has been deleted by a user. How does OneDrive will alert me. Currently I just Periodically check the count of DriveItem. Its a very primitive approach. I would like OneDrive to "Alert" me when its file is deleted by the user.

Thanks
Kyle Wang 5,531 Reputation points Microsoft Vendor

2021-07-21T09:45:35.067+00:00

@Universal Camera To avoid polling, you still need "Webhook call back". You can refer to Get notified of changes by using webhooks.
Universal Camera 276 Reputation points

2021-07-21T18:16:18.337+00:00

Back full circle

The tutorial if REST based. My app is NOT and converting the entire App to REST based is impossible since I like to stay in framework of Visual Studio.

Someone like you with knowledge can adapt the REST solution in Visual Studio Graph Tutorial based implementation????

Thank you!
Kyle Wang 5,531 Reputation points Microsoft Vendor

2021-07-29T06:48:57.113+00:00

@Universal Camera Well, polling is the preferred option. For any more issues, please provide any feedback in the GitHub repository.
Universal Camera 276 Reputation points

2021-07-30T15:50:54.7+00:00

Thank you

I created an issue on GIT

https://github.com/microsoftgraph/msgraph-training-xamarin/issues/28

this resulted in response

@GolfMan2000 unfortunately we're not able to provide developer support in our GitHub sample repositories. As mentioned in that thread, there is a Learn module for working with change notifications. We also have a .NET sample. Note that Graph sends change notifications via a webhook, which means you have to have some sort of web endpoint protected with SSL for Graph to send the notification too. I'm not sure this is possible in Xamarin.

I guess this confirms your idea of Polling as best solution!!!

1 answer

Jason Johnston 1 Reputation point

2021-08-04T18:22:25.707+00:00

Graph cannot notify your mobile app directly. If you want Graph to proactively notify your app of a change, you have to either stand up a web service to receive a POST from Graph (typically referred to as a webhook) and then work out some method to have your web service notify your mobile app, or you have to setup an Azure event hub and devise some method for the event hub to notify back to your mobile app.

Alternatively, you could instead just have your mobile app use change tracking, making periodic calls to Graph to get any changes since the last call.
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Get Notification of folder change in Personal OneDrive using Xamarin CrossPlatform & Graph

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