I am currently investigating Streaming subscriptions.

Due to platform limitations we cannot use EWS Managed API which provides the StreamingSubscriptionConnection.

According to How to: Stream notifications about mailbox events by using EWS in Exchange you would use a GetStreamingEvents EWS call to retrieve notifications.

Are there any ressources about implementing your own StreamingSubscriptionConnection as a Keep-alive socket Connection? I would like to get updates in real time, not every 15min or the like with a GetStreamingEvents call.

The main issue we have are customers with very large Folders (10k+ items) who do not want to synchronize the whole Folder to the device (Smartphone). As the syncFolderItems Operation cannot be limited we are looking into alternatives for These customers.

bump

I'm not aware of any non-managed API sample. However, the managed API is open-source, so you could steal from their code :). https://github.com/OfficeDev/ews-managed-api/

Thanks, i was not Aware of that being open source, i'll look through it.

Seems to be quite complicated though, for the last half hour i did not find out where the StreamingSubscription Connection is actually opened, so i am thankful for any pointers. Probably does not help that i am not fluent in c#