Real time web with SignalR

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

WEB06 WEB IN REAL TIME CON ASP.NET SIGNALR

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

Grazie a

Sponsor

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

Agenda• What / Why / When

• Event-driven architecture and SignlaR

• Scale-out SignalR

• Performance tips

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

About meAlessandro MelchioriSoftware architect @ codiceplastico

@amelchiori

http://melkio.blog.codiceplastico.com

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

demoSignalR.Intro

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

Pres

enta

tion

Laye

r

Serv

ice

Laye

r

Dom

ain

Mod

el

Storage

Da qui…

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

Pres

enta

tion

Laye

r

Serv

ice

Laye

r

Dom

ain

Mod

el

Write storage

Read storage

…a qui

message bus

SignalR core architecture: pub/sub

message cache

publisher

client client client client

- serializzazione- salvataggio in cache- “deliverable”

client

worker worker worker

- selezione worker- recupero messaggio

notifica al client (over specific transport)

Pattern 1. Server broadcast

• Low rate broadcast of the same payload to all clients

• One message bus send maps to many users (fan out)

• More clients don’t increase message bus traffic

Pattern 2. Server push

• Low rate broadcast of the unique payload to each client

• One message bus send maps to one user (no fan out)

• More clients means more message bus traffic

Pattern 3. User event driven

• Broadcast on client actions

• One message bus send maps to many users (fan out)

• More clients means more message bus traffic

Pattern 4. High frequency real-time

• Fixed high rate broadcast from servers and clients

• One message bus send maps to one user (no fan out)

• More clients means more message bus traffic

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

demoEvent-driven architecture & SignalR

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

Remember…

Have your app do as little as possible. If you do nothing, you can scale infinitely.

Scott Hanselman

Scale-out issues: message delivery

?How do messages from one server get

to the other servers in my web farm?

Scale-out issues: client transience

server 1

client

server 2

When is a client disconnected from

my app?

How do I avoid duplicate & missed

messages as I move from server to

server?

Scale-out issues: client distribution

server 1 server 2

client “foo”

client “foo”

client “foo,bar”

client “foo”

client “bar”

client “bar”

client “foo”

client “foo”

What happens if “foo” clients get many

more messages than others?

Scale-out SignalR

• SQL Server, Redis & Windows Azure Service Bus

• Great for the server broadcast load pattern

• Limited for other scenarios Every message goes to every server, so as traffic increases you’re

limited by how fast any one web server can pull messages off of the backplane

Backplanes are *much* slower than single-server performance

Scale-out provider architecture

web nodes

clients

backplaneMessages sharded

over multiple backplane streams

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

demoScale-out SignalR

#CDays14 – Milano 25, 26 e 27 Febbraio 2014

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