The relay server never initiates a connection to the Groove client on port 80 (914635)

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Groove does not accept incoming connections on port 80. If Groove cannot communicate with a peer or relay server over Simple Symmetrical Transfer Protocol (SSTP) on port 2492, Groove sends communications to remote port 80 because most firewalls allow outgoing traffic to port 80.

For a connection over port 80, communications will always go through a Groove relay server. Connections to a Groove relay server are initiated by the Groove client, never by the relay server.

The following list describes how Groove fetches data over HTTP:

1. The Groove client sends an HTTP post message to the Groove relay server.
2. The Groove relay server sends back some waiting data, together with information about how much data remains to be delivered.

These two steps are repeated until all data is transferred from the relay server to the Groove client. If the network environment allows, Groove uses several mechanisms to maintain the connection for more efficiency.