SignalR

B y E s r a a A m m a r

Topics Focused On!!!• Traditional Web Approach

– Traditional Web Approach – Issues

• What does “Real Time” mean?

• SignalR– Types of Transports– Types of Connections

• How do I get SignalR?

• Demo

Traditional Web Approach“Pulling”

CLIENT

SERVER

Traditional Web ApproachSends a Request to the Server – (Step 1)[In other words, the Client is trying to

pull some information from the Server]

Processes the Request

(Step 2)

Response Sent back to the Client – (Step 3)

• Not Persistent connection – IssuesEach time re-established for each communication.

• Http Request – Issues

Real Time Web Applications

What is Real Time Web Application?

• “Real Time” means an immediate response being sent by the Server to the Client.

• Real Time is “Pushing” instead of “Pulling”

• Push Technology is completely different from Pull Technology. Its about getting told what’s new, instead of asking for what’s new!!!

CLIENT

SERVER

User Sends a Request to the Server

Creates a Persistent Connection between them

Real Time Web Approach

Response Sent back to the Client

Response Sent back to the Client

Response Sent back to the Client

Comet Transports

Long Polling

Server

Client

Requ

est

Resp

onse

Variable delay

• Long polling does not create a persistent connection, but instead polls the server with a request that stays open until the server responds, at which point the connection closes, and a new connection is requested immediately.

Forever Frames• Internally creates an Iframe along with a

script on the page to fetch the data.

• The server then continually sends script to the client which is immediately executed, providing a one-way realtime connection from server to client.

• Supported on IE Browser.

HTML5 Transports

Server Sent Events

Server Sent Events• Requires a single connection between Client-Server.

• Works in server-to-client direction only

• Used to send Message Notifications or Continuous Data Streams.

• Support a lot of Browsers but Not supported in IE.

WebSocket

WebSocket• A new HTML5 API that enables bi-directional, full duplex

communication between the browser and server.

• Fastest solution

• Issues– Supported only on latest browsers – Works only with IIS-8.0

SignalR• SignalR is a library for ASP.NET developers. Used to

develop Real Time Web Application.

• Makes use of Push Technology.

• Provides Abstraction over the set of transports.

• Open Source available on Github!!!

SignalR

Transport Techniques

Connections

Transport Priority

WebSockets

Server-Sent events

Forever Frame (IE hack)

Long Polling

HTML 5 transports

Comet transports

SignalR Connections

Hubs

Persistent Connection

Persistent Connection

• low-level control to manage connection.

• Contain events like “OnConnection”, “OnDisconnection”, “OnReconnection”

• We can write our own logic in these events.

Hubs

Hubs

• Provides a High-level API.

• Client calling Server.

• Server calling Clients. (All, Groups, One).

• Broadcasting messages to all connected clients.

Connection lifetime

Connection lifetime

How do I get SignalR?

Install-Package Microsoft.AspNet.SignalR

Some References

Routing is Very Important

Server Calling Client

Client Calling Server Function

DEMO