>>The service bus is on the MS cloud. The example is basically a WVF service that is routed via the service bus. The advantages of this approach are that (a) it makes it simple to connect the client/server and, once the connection is made, they can usually communicate directly (i.e. not via the bus) and (b) brings in the possibility of queueing messages on the cloud for clients who are not always connected.
>>
>>If neither of those is of benefit to you then you could just write your own WCF service using wsDualHttpBinding to give duplex communications between client and server. See:
>>http://msdn.microsoft.com/en-us/library/ms731064.aspx
>>Snip:
>>"A duplex service contract is a message exchange pattern in which both endpoints can send messages to the other independently. A duplex service, therefore, can send messages back to the client endpoint, providing event-like behavior."
>
>This is more like it. We cannot put in the cloud confidential corporate data. This has to be a direct communication between both of our applications. The duplex service contract message seems to be more what I am looking for.

I wasn't suggesting storing data on the cloud. The service bus just provides a transport mechanism - which, BTW, is encrypted end to end. But you're right - a duplex service is probably the best bet for your needs....