SignalR

  • SignalR 1 Incredibly simple real-time web for ASP .NET
  • Hub protocol 2 specs
  • PS course Real-time applications using ASP.NET Core, SignalR & Angular 3 oct 16 & demo app 4
  • SignalR-plus-RX-Streaming-Data-Demo-App 5
  • SSE (server sent events) is a html5 feature. server response content type text/event-stream. js must instantiate an EventSource object. Easilt polyfilled for older browsers?
  • web sockets are a standardized way to use a TCP socket through which messages can be sent full duplex
  • lifetime of a web socket: http handshake, data exchange, close. all inside the same TCP socket.
  • web socket handshake
    • upgrade request. client sends random string
    GET /chat HTTP/1.1
Host: server.chat.com
Origin: client.chat.com
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: dfsddscxvb
Sec-WebSocket-Protocol: chat, superchat
Sec-WebSocket-Version: 13
Sec-WebSocket-Extensions: deflate-stream
    • 101 fine (switching protocols) response. Sends key back in accept header. Server add constant and hashes and base64 encodes.
    HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: vcbvcbasdef
Sec-WebSocket-Protocol: chat
Sec-WebSockets-Extensions: deflate-stream
  • message is composed out of multiple frames with header bits to determine last frame. text msg converted to binary
  • realtime web apps: polling, long polling, sse and signalr. named transports, fallback mechanism integrated from most efficient to polling.
  • client side signalr libraries?
  • uses RPC for communication.
  • hub server side class that sends/receives messages to/from clients.
  • protocol is the serialization format: msgpack 6 Compare with protobuf, JSON, ZeroFormatter. Microsoft.AspNetCore.SignalR.Protocols.[Json|MessagePack|NewtonsoftJson]. MessagePackHubProtocol src 7, proj 8, DI extensions 9, json hub protocol impl 10
  • configuration docs 11.
  • Under the Covers of ASP.NET Core SignalR article may 2018 12
  • The client side of a SignalR app needs a SignalR library @aspnet/signalr-protocol-msgpack
  • Azure SignalR Service
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