Is it possible to push XML messages to 3rd parties using SignalR or XSockets?
When I say 3rd parties I mean other website's clients.
Sure. Both SignalR and XSockets.NET can do that. XSockets can actually push the messages to "anything" since there are templates for implementing custom protocols in XSockets and XSockets supports "cross-protcol communication".
By cross protocol I mean that you can connect anything having a network connection and let that "thing" publish/subscribe to events from XSockets.
Maybe a little bit of topic from what you asked but it opens up new possibilities when you can communicate between a browser and ANYTHING! :)
Regards Uffe