Using the Service Bus as a relay service

The Windows Azure AppFabric Service Bus provides a relay service allowing communication between a client and a server even when the server is located behind a firewall. The Service Bus does this by providing a public endpoint for the service. A client, who could not ordinarily punch through the firewall, can connect in a secure manner to the public endpoint and the Service Bus relays this connection through the firewall to the service. The Service Bus implements this capability by fusing an outbound connection from the server with an outbound connection from the client. Consequently, the firewall does need to allow an outbound connection, but it does not need to allow an inbound connection. Under certain circumstances, the Service Bus may upgrade the connection, so that it goes directly between the client and the server bypassing the Service Bus relay endpoint completely, thereby providing a much faster connection. This is similar to the way instant...