Why?

Live content

What is happening with the data outside the current application instance?

someone else could:

• add
• remove
• modify

Who?

• an user
• a process
• another application

What we need to do?

• Refresh it!

How?

Press F5

or Ctrl-R

or hit the refresh button

The foundation of the web

http

works over TCP/IP

request
response

a client - request -> URI

Resource <- a server response

Hyperlinks

So, yes, you need to refresh your browser

fortunately we can dev rich applications for browsers

(Javascript)

Techniques 

• scheduled request
• Forever frame
• Ajax long-pooling

Modern techniques

• Websockets
• Server Sent Events

Signalr

Abstraction for

• Forever frame
• Long pooling
• Websockets
• Server sent events

through two models of communication

Persistent connections

Low level communication API

Hubs

High level communication API

Allows to call function

• From server to client
• From client to server

Build over Persistent Connection API

Send message

• one specific client
• group of clients
• all clients (broadcast)

For our business case?

we can use Signalr for

• push new songs in the user feed
• notify "likes" or new comments over our songs
• live comments

Setup your dev env

Install

• .NET Core -> https://www.microsoft.com/net
• Visual Studio Code -> https://code.visualstudio.com

yeoman

npm install -g yo generator-aspnet bower

Create a Signalr app

Create an ASP.NET App

yo aspnet

Select Basic Application

... and Boostrap

Run the base app

dotnet restore
dotnet run

Open the app on VS Code

code . #remember to specify the path

Marginals App

• Send a message to everybody when somebody feels like a marginal
• Send a "Wake up marginal!" to someone

Server

AllMarginals (Hub)

Message for all

OneMarginals (Hub)