Difference between SignalR protocol version 1.2 and 1.3?

Question

What's the difference between version 1.2 and 1.3 of the SignalR protocol? I've checked the release notes and the github repo but can't figure out what is changed.

Answer 1

The big change is when clients decide they are "connected". In the 1.3 protocol, an initialization message is sent back to the client and only then do clients consider themselves connected. Relevant code:

https://github.com/SignalR/SignalR/blob/dev/src/Microsoft.AspNet.SignalR.Client/Transports/TransportHelper.cs#L244

Answer 2

This may be an incomplete list of changes I noticed when the client uses longPolling:

On the negotiate GET request, the client protocol and connection data are added as GET params to the URL:

• 1.2 was simply ~/signalr/negotiate
• 1.3 is ~/signalr/negotiate?clientProtocol=1.3&connectionData=[names of hubs]

In the negotiate JSON repsonse, the clientProtocol is now 1.3 instead of 1.2.

On the send POST request for longPolling, the connectionData (names of hubs) is added to the URL.

On longPoll responses from the server, as dfowler mentions, an "S" was added that initializes the connection.