EWS - Office 365 - "One or more subscriptions in the request reside on another Client Access server. GetStreamingEvents won't proxy in the event of a batch request."

Question

Hello
My goal is to subscribe for streaming notifications for multiple users in the same time.
One way to do that is to create multiple  StreamingSubscriptionConnections each one should contain one  StreamingSubscription for each user. The problem with this method is that in Office 365 the maximum
number of connections opened is 20.
Another method to solve this problem is by creating one StreamingSubscriptionConnection and then all StreamingSubscriptions for each user to the connection. This method solves the maximum number of connections
problem and it works fine with exchange onPrimises. But when trying it with Office 365 it will result with the SubscriptionError:
"One or more subscriptions in the request reside on another Client Access server. GetStreamingEvents won't proxy in the event of a batch request."
Can anyone help me here ? 

Answer 1

With Office365 you need to Group your subscriptions and set the Affinityheaders see
http://msdn.microsoft.com/en-us/library/office/dn458789(v=exchg.150).aspx and
http://blogs.msdn.com/b/mstehle/archive/2013/07/17/more-affinity-considerations-for-exchange-online-and-exchange-2013.aspx . Take note of the restrictions on the Group and other throttling restrictions if your using only one service account.
Cheers
Glen