SIGNALR : INCREDIBLY SIMPLE REAL-TIME FOR ASP.NET

COȘCODAN MIHAIL

SUMMARY• DEFINING PROBLEM SPACE

• EXISTING TECHNOLOGIES

• INTRODUCTION TO SIGNALR

• ARCHITECTURE AND COMPONENTS

• DEMO/EXAMPLES

THE PROBLEM: CLIENT WANT FRESH DATA• You (the «customer») want latest info (data)!

• You need them NOW!

• Real Time!

Examples of apps :

• Twitter / Facebook / many more…

• Notifications.

• Auctions / Stock trading / Banking.

• Live user analitics

• Search/update

• Collaborative apps(Google docs,

• Interactive games

REAL TIME APPLICATIONS, DEVELOPER VIEW

• Persistent Connections between endpoints.

• Two way communication (full-duplex).

• Low Latency ( :D ).

• Low overhead.

• Over the «wire» (intranet/internet/generic communication medium).

EXISTING TECHNIQUES/SOLUTIONS

• Pooling;

• Long Pooling;

• Forever Frame;

• Server Sent Events(SSE);

• WebSockets;

PERIODIC POLLING

Poll from time to time using Ajax Delay in communication due to polling interval Wastes bandwidth & latency & resources

Server

ClientPolling interval

LONG POLLING

Poll but doesn’t respond until there's data Poll again after data received or after the connection times out Consumes server & threads & connection resources Better than the previous one: less requests.

Server

Client

FOREVER FRAME

Server

Client

This technique is very low-latency because it avoids HTTP and TCP/IP set-up and tear-down by reusing a single long-lived connection. It uses "chunked encoding", a feature of HTTP/1.1 intended for an entirely different purpose, but which allows the server to maintain a connection to the client indefinitely, sending additional data to the client at will.

IFRAME ("Forever frame"): Loading a page in an IFRAME that incrementally receives commands wrapped in <script> tags, which the browser evaluates as they are received.

• Data is sent out in chunks.• Add an IFrame to the page (its content length is declared to be

indefinitely long).• Load in the IFrame a page with a script in it (execute it to get your

chunk of data).• The next chunk of data arrives in the form of another script that is

executed again.• The cycle goes on and on and on...

It causes pollution in the long run…all those script tags stays there even if you don’t need them anymore.

FOREVER FRAME IE WAY

Server-Sent Events (SSE) are a standard describing how servers can initiate data transmission towards clients once an initial client connection has been established. They are commonly used to send message updates or continuous data streams to a browser client and designed to enhance native, cross-browser streaming through a JavaScript API called EventSource, through which a client requests a particular URL in order to receive an event stream.

Server-Sent Events (SSE)

HOW TO BUILD REAL-TIME WEB APPS?

Never designed for real-time communications

Web is all about request-response

Web is stateless

INTRODUCTING SIGNALR HISTORY

• Signal R was created as an open source project by two Microsoft employees: David Fowler & Damien Edwards

• Adopted by Microsoft, but remains open source on GitHub

• Like jQuery for communication

• Distributed via NuGet

INTRODUCTING SIGNALR

• SignalR is a series of abstractions around a few persistent HTTP techniques(library).

• Persistent Connection Abstraction communication library.

• Abstracts protocol and transfer (choses the best one).

• A single programming model (a unified development experience).

• Extremely simple to use.

• Server-side it can be hosted in different «environments» (ASP.NET, console apps, windows services, etc…).

• Client-side there’s support for: Javascript clients, .NET clients, WP; provide by the community: iOS, Android.

SIGNALR COMPONENTS

Clients.NET 4.0+

JavaScript

Windows store apps

Silverlight 5

Windows Phone 8

iOS

Android

Hosts

ASP.NET

OWIN

Backplanes

SQL

Service Bus

Redis

ARCHITECTURE DIAGRAM

Picture was taken from http://www.asp.net/signalr

SIGNALR: SETUP DEMO

Demo: how to setup SignalR,

GitHub or NuGet,

see websockets in action.

TWO LEVELS OF ABSTRACTION

Picture was taken from book ASP.NET SignalR Incredibily simple real-time features for your web apps by Jose M. Aguilar

CONCEPTUAL IMPLEMENTATION OF PERSISTENT CONNECTIONS

CONCEPTUAL IMPLEMENTATION OF HUBS

The use of hubs is recommended when we need to send different types ofmessages with various structures between the client and the server.

CONCLUSIONS

• SignalR is a server-side software system designed for writing scalable Internet applications, notably web servers. Programs are written on the server side in C#, using event-driven, asynchronous I/O to minimize overhead and maximize scalability.

• SignalR takes advantage of several transports, automatically selecting the best available transport given the client's and server's best available transport.

RESOURCES

Microsoft ASP.NET SignalR: The Real-Time Web Made Simplehttp://channel9.msdn.com/Events/TechEd/NorthAmerica/2013/DEV-B302

Building Real-time Web Apps with ASP.NET SignalRhttp://channel9.msdn.com/Events/Build/2012/3-034

Introducing ASP.NET SignalR - Push Services with Hubshttp://pluralsight.com/training/courses/TableOfContents?courseName=signalr-

introductiongithub.com/SignalR/SignalRhttps://html.spec.whatwg.org/multipage/comms.html

TIME FOR SOME Q&A

THANK ALL FOR ATTENDING