We have customers that are starting to move to Office 365, and in our current solution we depend on the push subscriptions, where we provide a callback URL. In the Office 365 scenario our customers does not like to open up the firewall to allow these connections and instead we are now looking into streaming subscriptions.

No my problem is that I am not sure whether using streaming subscriptions I need to open up a HTTP connection for each mailbox, or if I with impersonation can open just one connection for each impersonation account servicing multiple mailboxes. If the latter is the case, can you provide an example with either EWS Managed API or the EWS Java API?

• Edited by homaxto Friday, November 22, 2013 12:49 PM improving title

"Streaming notifications rely on a hanging get request" see http://msdn.microsoft.com/en-us/library/office/dn458791(v=exchg.150).aspx

This means that for every Mailbox your subscribing to you will have one of these hanging connections. This is simular to how ActiveSync Push notificaitons work so its generally reliable and scalable. Impersonation has no affect on the number of connections as subscriptions are per mailbox, it does help with throttling because the concurrent connections are charged against the Mailbox owner see http://blogs.msdn.com/b/exchangedev/archive/2012/04/19/more-throttling-changes-for-exchange-online.aspx

cheers
Glen