SignalR is a library for adding real-time web functionality to applications. It uses web sockets, server-sent events, and long-polling to enable real-time functionality between a server and client browsers. SignalR supports cross-platform connections from JavaScript and .NET clients to any backend. Hubs provide a simple abstraction for defining real-time endpoints and handling connections that can scale across servers. A backplane like Redis can be used to enable real-time connections across servers for scaling out applications. SignalR can also be self-hosted outside of IIS.

1. SignalR
Simplest way to achieve real-time web functionality

2. Agenda
• Introduction
• Hubs
• Scale Out / Backplane
• Self Host

3. Intro to SignalR
• A library for real-time web functionality
• Built on OWIN(SignalR 2.x)
• Open Web Interface for .Net
• Open source on Github

4. Intro to SignalR
• Built on persistent connections
• Remote Procedure Call(RPC)
• Server push
• Transports
• Web Socket
• Server Sent Event
• Forever Frame
• Long Polling
• Fallback

5. Transports
comet HTML 5
Long Polling Forever Frame
Server Sent
Event
Web Socket

6. Long Polling
• Response when server data
changed

7. Forever Frame
• Hidden iframe
• Only for IE

8. Server Sent Event
• HTML5 EventSource
• One way communication
(Server to client)
• Except IE

9. Web Socket
• Persistent full-duplex
bi-directional connection
• Criteria are met for both
server and client side

10. Web Browser Transport Requirements
Transport
Internet
Explorer
Chrome
(Windows or
iOS)
Firefox
Safari
(OSX or iOS)
Android
WebSockets 10+ current - 1 current - 1 current – 1 N/A
Server-Sent
Events
N/A current - 1 current - 1 current - 1 N/A
ForeverFrame 8+ N/A N/A N/A 4.1
Long Polling 8+ current – 1 current - 1 current - 1 4.1

11. Core Architecture
• pub/sub
• Publish-Subscribe pattern

12. Core Architecture
publisher
message cache
worker worker worker
client client client client client
message bus
1.Message serialized,
saved to cache
associated with signal,
topic is marked for
delivery, publish call
returns
2. Worker is scheduled for
a signal, selects a waiting
subscriber, retrieves
message from cache
3. Worker sends message
to client as bytes over a
transport

13. Watch out
• Sending large messages
• Memory leaks – all hub instances are transient
• Session – don’t use it from SignalR, at all, ever (no support)

14. Platform Support
• OS
• Windows 2008 r2 to 2012
• Windows 7+
• Windows Azure(No support Web Socket)
• .Net framework
• .Net 4.5+(Web Socket support)
• .Net 4
• IIS
• IIS 8(Web Socket support)
• IIS 7 and IIS 7.5

15. Hubs
• Least developer work
• Monitor network transport
• Specifying network technology
• Accept/Return simple type, complex type
• Complex objects serialized to/from JSON

16. Hubs-Server side
• Register in Startup.cs
• HubName attribute
• Broadcast
• Clients.All.dynamic
• Clients.Caller.dynamic
• Clients.Others.dynamic
• Clients.Caller(Context.ConnectionId).dynamic
• Clients.AllExcept(connectionId, connectionId).dynamic
• Clients.User(userId).dynamic
PM> Install-Package Microsoft.AspNet.SignalR
public partial class Startup
{
public void Configuration(IAppBuilder app)
{
app.MapSignalR();
}
}
[HubName("alias")]
public class NewHub : Hub
{
}

17. Hubs-Client side
• jQuery base
• $.connection.hubName -> Camelcase
• $.connection.hub.start()
• $.connection.hub.start({ transport: [‘webSockets’,
‘longPolling’] })
• $.connection.hub.logging = true -> Debugging
• hub.server.serverMethod
• hub.client.dynamicMethod
<script src="~/scripts/jquery-
1.6.4.min.js"></script>
<script src="~/scripts/jquery.signalR-
2.2.0.js"></script>
<script src="~/SignalR/hubs"></script>
PM> Install-Package Microsoft.AspNet.SignalR.JS

18. Hubs
• Server
• OnConnected
• OnReconnected
• OnDisconnected
• Client
• $.connection.hub.start
• $.connection.hub.reconnecting
• $.connection.hub.disconnected
• $.connection.hub.connectionSlow

19. DEMO: First SignalR

20. Hubs
• Groups
• Send message to particular groups
• Not persisted on server
• Server side
• Groups.Add(Context.ConnectionId, groupName)
• Groups.Remove(Context.ConnectionId, groupName)
• Broadcast
• Clients.Group(groupName).dynamic
• Clients.Group(groupName, connectionId,
connectionId).dynamic
• Clients.OthersInGroup(groupName).dynamic

21. DEMO: UKWL with SignalR

22. Scale out
• Problem
client
Server 1 Server 2

23. Scale out + Backplane
Backplane
clien
t
Server
clien
t
clien
t
clien
t
clien
t
clien
t
Server
clien
t
clien
t
clien
t
clien
t
clien
t
Server
clien
t
clien
t
clien
t
clien
t

24. Backplane
• HOW TO
• Nuget + ONE line code
• Limitation
• Much slower than single server
• Lower rate

25. Load patterns
• Server broadcast – low rate, message to all clients
• Server push – low rate, message to unique clients
• User event driven – broadcast on client action
• High frequency – fixed high rate, unique messages

26. Backplane
• Redis
• SQL Server
• Azure Service Bus
PM> Install-Package Microsoft.AspNet.SignalR.Redis
public partial class Startup
{
public void Configuration(IAppBuilder app)
{
app.MapSignalR();
}
}
GlobalHost.DependencyResolver.UseRedis("server", port, "password",
"AppName");

27. DEMO: Scale out with Redis

28. Self host
• Normally hosted in IIS
• WHY self-hosted
• No IIS
• Performance issue
• Console / Windows Form Application

29. Self host - Server
class Program
{
static void Main(string[] args)
{
using (WebApp.Start("http://localhost:8080")) {
Console.ReadLine();
}
}
}
class Startup
{
public void Configuration(IAppBuilder app)
{
app.UseCors(CorsOptions.AllowAll);
app.MapSignalR();
}
}
PM> Install-Package Microsoft.AspNet.SignalR.SelfHost
PM> Install-Package Microsoft.Owin.Cors

30. Self host - Client
<script type="text/javascript">
$(function () {
$.connection.hub.url = "http://localhost:8080/signalr";
});
</script>
PM> Install-Package Microsoft.AspNet.SignalR.JS
<script src="~/scripts/jquery-1.6.4.min.js"></script>
<script src="~/scripts/jquery.signalR-2.2.0.js"></script>
<script src="http://localhost:8080/signalr/hubs"></script>

31. Q & A