SignalR - Realtime client/server communication (iSense)
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Today’s users are interested in a rich experience where the terms client and server don’t mean a thing. They expect real-time action between both, no matter if the technology used is HTML5 websockets or something else. This session will cover SignalR and show you how it can be used to communicate in real time between the client and server, using HTML5 or not. Combine SignalR with ASP.NET MVC, JavaScript and perhaps a sprinkle of Azure and you’ll have an interesting, reliable and fast stack to build your real-time client-server and server-client communications. Join me on this journey between web, cloud and user. No toothpaste. Just code.
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SignalR - Realtime client/server communication (iSense)
- 2. R
- 3. Who am I? Maarten Balliauw Antwerp, Belgium Developer Advocate, JetBrains Founder, MyGet AZUG Focus on web ASP.NET MVC, Azure, SignalR, ... Former MVP Azure & ASPInsider Big passion: Azure http://blog.maartenballiauw.be @maartenballiauw
- 4. Agenda Why real-time & how? Meet SignalR Connections and Hubs Clients .NET Core Q&A
- 5. Why real-time & how?
- 6. Users want the latest info, now! Twitter – live searches/updates Stock tickers Auctions Live scores Real-time notifications Collaborative apps Live user analytics Online gaming / browser games … 6
- 7. HTTP is and old beast Never designed for real-time communications Web is request-response Web is stateless Websockets to the rescue!
- 8. Websockets Extension to HTTP Provide raw sockets over HTTP Full-duplex, low latency Traverses proxies But… Not every proxy server supports it Not every webserver supports it Not every browser supports it Some antivirus blocks it They are raw sockets! (protocol: up to you) http://websocketstest.com/
- 9. Forever Frame Server tells client that response is chuncked Client keeps connection open untill server closes it Server pushes data to the client followed by 0 Consumes server threads HTTP/1.1 200 OK Content-Type: text/plain Transfer-Encoding: chunked <script>eval("... ")</script>0 <script>eval("... ")</script>0
- 10. Periodic polling Poll from time to time using Ajax Delay in communications due to polling interval Wastes bandwidth & latency Polling interval
- 11. Long polling Poll but don’t respond until there’s data Poll again after data received or after the connection times out Consumes server threads & connection resources
- 12. Options! Forever Frame Periodic polling Long polling Websockets (Server-Sent events)
- 13. SignalR
- 14. SignalR Three-in-one! “Persistent” client/server connection over best transport Connection negotiation Abstracts away the transport Provides just one programming model http://github.com/signalr/signalr - open source C#, JavaScript, UWP https://github.com/aspnet/signalr - new .NET Core version
- 16. What just happened? The server is broadcasting a message every few seconds Clients are receiving messages Code looks easy No polling or whatsoever (at least not in my code) SignalR decides on transport mechanism used based on client + server
- 18. Two programming models PERSISTENT CONNECTION Can communicate with 1..N clients Requires a route to be defined Limited to sending messages You define the “protocol” HUB Abstraction over PersistentConnection Can communicate with 1..N clients Route automatically mapped (/signalr/hubs) Can send messages and call methods SignalR defines the protocol
- 19. Hello, Hubs DEMO
- 20. Hubs Hub methods can be called from client Client methods can be called from hub Target individual client Target all clients Target group of clients http://shootr.signalr.net/
- 21. Clients
- 22. So far we have used... On the server side Host in any ASP.NET application (SignalR.Server) On the client side JavaScript (SignalR.JS) But there’s more…
- 24. There is more! On the server side Host in any ASP.NET application (SignalR.Server) or using self-hosting (OWIN based) Host on Azure Scale out (Redis, Azure Service Bus) (I did a NodeJS server as well, but don’t use it in production) On the client side JavaScript (SignalR.JS), Angular (AngularJs.SignalR.Hub) Any .NET client (SignalR.Client) UWP iOS Android
- 25. DeckCast DEMO
- 26. .NET Core
- 27. ASP.NET Core Sockets SignalR in the ASP.NET Core world Improvements based on SignalR learnings: No more jQuery No more iframe transport No more message replay after reconnect (memory usage, performance) No more Hub-state (I did not talk about this “ViewState” because it’s evil) Endpoint per Hub (/signalr/hubs /signalr/...) Scale-out now becomes scale-out (and not sending all messages everywhere) Sticky sessions required (sad )
- 28. ASP.NET Core Sockets New features: Cross-platform (including things like RaspberryPi) Binary data support (think sending images etc.) Host-agnostic (HTTP works but also TCP/UDP/... sockets) Protocol data format pluggable (JSON, protobuf, ...) TypeScript client ...
- 29. Demo? Will leave this one for you... Under development! https://github.com/aspnet/signalr Preview release mid-year Release later this year
- 30. Conclusion
- 31. Conclusion SignalR is three-in-one! “Persistent” client/server connection over best transport Abstracts away the transport Provides just one programming model Connections & Hubs Connect various clients
Notas do Editor
- https://pixabay.com
- https://pixabay.com/en/tires-used-tires-pfu-garbage-1846674/
- https://pixabay.com/en/tires-used-tires-pfu-garbage-1846674/
- https://pixabay.com/en/tires-used-tires-pfu-garbage-1846674/
- Open VS2017 Create a new ASP.NET Empty Website Install-Package Microsoft.AspNet.SignalR Note server library, client script, jQuery dependency Add startup class: public class Startup { public void Configuration(IAppBuilder app) { app.MapSignalR(); } } Add a class: public class TimeConnection : PersistentConnection { } Map the connection: app.MapSignalR<TimeConnection>("/time"); Add an infinite loop: ThreadPool.QueueUserWorkItem(_ => { var connection = GlobalHost.ConnectionManager.GetConnectionContext<TimeConnection>(); while (true) { connection.Connection.Broadcast(DateTime.UtcNow.ToString()); Thread.Sleep(1000); } }); Add some HTML: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title></title> <script src="Scripts/jquery-1.6.4.min.js" type="text/javascript"></script> <script src="Scripts/jquery.signalR-2.2.1.min.js" type="text/javascript"></script> <script type="text/javascript"> $(function () { var connection = $.connection('time'); connection.received(function(data) { $('h1').text('The time is ' + data); }); connection.start(); }); </script> </head> <body> <h1>The time is now!</h1> </body> </html> Now let’s take things easy… How does all of this work? Note that we are sending data TO THE CLIENT by just broadcasting on the connection View Chrome developer tools, in this case web sockets Add to web.config: (.vs\config\applicationhost.config) <system.webServer> <webSocket enabled="false"/> </system.webServer> View Chrome again, notice now event stream is used instead Install-Package Microsoft.AspNet.SignalR.Sample and show stock ticker in two browsers
- https://pixabay.com/en/tires-used-tires-pfu-garbage-1846674/
- Add simple chat hub [HubName("simplechat")] public class SimpleChatHub : Hub { private static readonly Dictionary<string, string> _users = new Dictionary<string, string>(); public async Task Join(string username) { _users[Context.ConnectionId] = username; await Clients.All.userJoined(username); } public async Task SendMessage(string message) { await Clients.All.messageReceived( _users[Context.ConnectionId], message); } } Explain: user joins, we store username passed linked to connection id We then call back to all clients, calling a JS function on there Client code: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title></title> <script src="Scripts/jquery-1.6.4.min.js" type="text/javascript"></script> <script src="Scripts/jquery.signalR-2.2.1.min.js" type="text/javascript"></script> <script src="/signalr/hubs"></script> <script type="text/javascript"> $(function () { var username = prompt('What is your name?'); $.connection.hub.logging = true; var hub = $.connection.simplechat; // User joined hub.client.userJoined = function (who) { $("#messages").append('<li><em>' + who + ' joined the chat.</em></li>'); }; // Message received hub.client.messageReceived = function (who, what) { $("#messages").append('<li>' + who + ': ' + what + '</li>'); }; // Join the chat $.connection.hub.start().done(function () { hub.server.join(username); }); // Bind client UI $('#message').change(function () { hub.server.sendMessage($('#message').val()); $('#message').val(''); $('#message').focus(); }); }); </script> </head> <body> <h1>Chat</h1> <ul id="messages"></ul> <input type="text" id="message"/> </body> </html> Explore hubs some more: different properties on the hub (clients all, per group, individual, ...)
- Create a new Console application Install-Package Microsoft.AspNet.SignalR.Client Add code var connection = new Connection("http://localhost:51736/time"); connection.Received += data => { Console.Clear(); Console.WriteLine(data); }; connection.Start(); Cool, so connection works! Now let’s try hubs and connect to our simple chat. Add code private static async Task RunAsync(string[] args) { _connection = new HubConnection("http://localhost:51736/signalr"); _hub = _connection.CreateHubProxy("simplechat"); _hub.On <string>("userJoined", userName => { Console.ForegroundColor = ConsoleColor.DarkYellow; Console.WriteLine($"{userName} joined."); Console.ResetColor(); }); _hub.On<string, string>("messageReceived", (userName, message) => { Console.ForegroundColor = ConsoleColor.Yellow; Console.WriteLine($"{userName}: {message}"); Console.ResetColor(); }); await _connection.Start(); // Join the chat Console.WriteLine("Your username:"); var myName = Console.ReadLine().Trim(); await _hub.Invoke("join", myName); // Send messages while (true) { var myMessage = Console.ReadLine().Trim(); if (!string.IsNullOrEmpty(myMessage)) { await _hub.Invoke("sendMessage", myMessage); } } }
- Open DeckCast Show people around and tell them about deck.js Show the presenter mode and client mode on the web Start a console based viewer Start a console based presenter
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