Real-time web experience with signalR. Slide deck from SDP 2013 session

1. SELA DEVELOPER PRACTICE
May 5-9, 2013
Ran Wahle
Real time Web experience with signalR

2. Agenda
• “Real Time” web techniques
• What is signalR
• SignalR protocol
• Hubs
• Groups and private messages
• .Net client
• Self Hosting
• Scaleout

3. Real-time web
Polling
ForeverFrames
Long-Polling
ServerSentEvents
WebSocket

4. Polling

5. Long Polling

6. Server Sent Events

7. Forever Frames

8. Web Socket
Web Socket Request
TCP Socket
ServerClient

9. Web socket
• Actual TCP socket between server and client
• HTML5 standard
• Supported by Windows server 2012 / Windows 8
• Supported by IE10+, Chrome, Firefox, Opera and
more

10. Web socket in code
Server (C#):
public void ProcessRequest(HttpContext context)
{
HttpContext.Current.
AcceptWebSocketRequest
(new ChatWebSocketHandler());
context.Response.StatusCode
=(int)HttpStatusCode.SwitchingProtocols;
}
Client: (javascript)
var websocket = new window.WebSocket(“ws://<web socket url>”);

11. Web socket in code
Server (C#)
public class MyWebSocketHandler :
WebSocketHandler
public override void OnOpen()
public override void OnError()
public override void OnMessage(string
message)
Client (Javascript)
websocket.onopen = function () { …}
websocket.onerror = function(data) {…}
websocket.onmessage = function (event) {

12. WebSocket is not enough
• Not all servers support web sockets
• Not all network components support web sockets
• It’s API is limited

13. What do we need?
• Code once, deploy everywhere
• As cross-platform as possible
• Simple API to work with

14. What is signalR
• Open source project
• Abstraction layer over connection technique
• Can be self-hosted
• Call client methods from the server
ServerSentEvents
=
Polling
ForeverFrames
Long-Polling
WebSocket

15. So, why not WebSocket
WebSocket
• Good performance
• Strict prerequisites
• Limited API
SignalR
• Abstraction layer
• Rich API
• Supports WebSocket

16. Getting started
“Every time I see live-coding I get down on my knees
and pray”
Anonymous narrator

17. Protocol
Negotiate request
Negotiate response
Connection phase
Client
Server

18. Try it yourself
http://ranw.azurewebsites.net/chatpage.html

19. Hub
• Abstraction over signalR connection
• Service-like API
• Call clients methods from the server

20. Hub
Server (C#)
public void ServerMethod(args)
{
…..
}
private void SendToClient()
{
Clients.All.doSomething(args);
}
Client (Javascript)
hub.server.serverMethod(args);
hub.client.doSomething = function(args)
{
…
};

21. Private messages
• You can use connection ID
• You can access a particular client by it
Clients.Client(connectionId).sendMessage(message)

22. Groups
• Part of Hub API
• Stored on client
• Not persistent
Groups.Add(Context.ConnectionId, groupName);
Clients.Group(groupName).invokeSomeClientMethod(args…);

23. .Net client
_connection = new HubConnection(“Server Url");
IHubProxy proxy = connection.CreateHubProxy(“Hub Name");
_connection.Start().ContinueWith(
//define proxies
);
//invoke server methods
_proxy.Invoke(“HubServerMethod“ , args…));

24. Self hosting
• Three NuGet packages to install
Microsoft.Owin.Hosting
Microsoft.Owin.Host.HttpListener
Microsoft.AspNet.SignalR.Owin
• Create class with Configuration method.
• Map hub in the Configuration method
• Use the class as a type parameter to
WebApplication.Start

25. ScaleOut with Redis
• Install Redis for Linux or Clone the windows porting
• Add One line of code
GlobalHost.DependencyResolver.UseRedis(“<server>", <port>, “<password>", “<
storagekey>");
• On Windows – run redis from command line
• Your app is ready to scaleout

26. What have we seen today?
• Real time experience is more than just polling
• Using signalR can use the best available technique
• It can be self hosted
• It can scale out
• It has several clients

27. Other resources
•http://www.asp.net/signalr
•http://signalr.net/
•Twitters:@signalr @DamianEdwards @davidfowl
and @DavianFowlwards
•http://blogs.Microsoft.co.il/blogs/ranw

28. Thank You
Ran Wahle
ranw@sela.co.il
http://blogs.Microsoft.co.il/blogs/ranw