SignalR Client Default Fallback Transport

Question

For the case of an SignalR client using .Net Framework 4.0 to connect to the server (therefore no WebSockets transport supported) which would be the next fallback transport ?

Moreover, if there is a fallback chain it would be great to know it.

Answer 1

From https://docs.microsoft.com/en-us/aspnet/signalr/overview/getting-started/introduction-to-signalr#transports-and-fallbacks the following are used if WebSockets is unavailable:

• Server Sent Events, also known as EventSource (if the browser supports Server Sent Events, which is basically all browsers except Internet Explorer.)
• Forever Frame (for Internet Explorer only). Forever Frame creates a hidden IFrame which makes a request to an endpoint on the server that does not complete. The server then continually sends script to the client which is immediately executed, providing a one-way realtime connection from server to client. The connection from client to server uses a separate connection from the server to client connection, and like a standard HTML request, a new connection is created for each piece of data that needs to be sent.
• Ajax long polling. Long polling does not create a persistent connection, but instead polls the server with a request that stays open until the server responds, at which point the connection closes, and a new connection is requested immediately. This may introduce some latency while the connection resets.

Update: The latest docs are available here: http://www.asp.net/signalr/overview/signalr-20/getting-started-with-signalr-20/introduction-to-signalr