SignalRRealtime client/server communicationMaarten Balliauw@maartenballiauw

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Who am I?

Maarten Balliauw

Antwerp, Belgium

Developer Advocate, JetBrains

Founder, MyGet

AZUG

Focus on webASP.NET MVC, Azure, SignalR, ...Former MVP Azure & ASPInsider

Big passion: Azure

http://blog.maartenballiauw.be

@maartenballiauw

Agenda

Why real-time & how?

Meet SignalR

Connections and Hubs

Clients

.NET Core

Q&A

Why real-time & how?

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

HTTP is and old beast

Never designed for real-time communications

Web is request-response

Web is stateless

Websockets to the rescue!

Websockets

Extension to HTTP

Provide raw sockets over HTTP

Full-duplex, low latency

Traverses proxies

But…Not every proxy server supports itNot every webserver supports itNot every browser supports itSome antivirus blocks itThey are raw sockets! (protocol: up to you)

http://websocketstest.com/

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 OKContent-Type: text/plainTransfer-Encoding: chunked

<script>eval("... ")</script>\0

<script>eval("... ")</script>\0

Periodic polling

Poll from time to time using Ajax

Delay in communications due to polling interval

Wastes bandwidth & latency

Polling interval

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

Options!Forever Frame

Periodic polling

Long polling

Websockets

(Server-Sent events)

SignalR

SignalR

Three-in-one!“Persistent” client/server connection over best transport

Connection negotiation

Abstracts away the transportProvides just one programming model

http://github.com/signalr/signalr - open sourceC#, JavaScript, UWP

https://github.com/aspnet/signalr - new .NET Core version

Hello, SignalRDEMO

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

Connections and Hubs

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

Hello, HubsDEMO

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/

Clients

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…

Connecting to SignalR DEMO

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

DeckCastDEMO

.NET Core

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 )

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

...

Demo?

Will leave this one for you...

Under development! https://github.com/aspnet/signalr

Preview release mid-year

Release later this year

Conclusion

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

Thank you!http://blog.maartenballiauw.be

@maartenballiauw