The Realtime Web
!Bert Wijnants end2end engineer @ Mobile Vikings
@bertwww www.newpage.be
Fronteers meetup - 5 december 2013
wooooooow websockets are so cool!
Live on television
Do web sockets make the internet realtime?
Why is this the realtime web?
The obvious stuff
ticker: realtime push updates
The obvious stuff
chatbox
But there’s a lot more…
super fast search
But there’s a lot more…load content with ajax
TTI: Time To InteractThe perceptual speed for user to be able to start interacting
Time To Interact
<100ms: damn this app is fast, dude!
100ms - 300ms: this app is responding to my input
300ms - 500ms: mmmm, my brother is downloading some torrents again, the internet is slow
>500ms: Hey brother! Stop streaming those torrents, i’m trying to use the internet here.
we live in the intergalactic cloud, right?
Impossible to avoid the latencies
Don’t let the dark side betray youThey will say: “our servers are at full speed, they can’t be faster.”
…though it does not feel fast to your users
Why is your ajax call soooo slow?
http request handshaking
server-side script running on shared resources
network latency to database
database query
http request: data transfer
Stop hugging it!
Back-end developers just love their database
Don’t put your program logic in the back-end
your users are waiting for every decision..
Front-end developers to the rescue!
It’s not that hard nowadays. You don’t need to learn linux or whatever…
Learn some back-end you must
Strategy for realtime appsfor end2end developers
Store data client-side Persist data server-side
query the database once when app starts
download all user-specific data needed
all users get same static content: 100% cache hit, so make sure you’re database caching is on!
this might take a few seconds the first time,.. show some static stuff to user first
Push changes to clients
When data changes
Push changes to clients immediately
use websockets or long polling: always open connection
example: search box
Search box with auto-complete
A field to search for users based on phone number or name
180.000 users
example: auto-complete
On startup: download all users from database (id, name, phone number)
Same query for every one: served directly from database cache!
Not that fast: takes 2 seconds! ouch
What, 2 seconds?!?!
Static content is served from cache and rendered immediately (100ms)
Your user has to move to the search box (1.5s)
Your user must start typing (300ms)
And type up to 3 letters (300ms) before we start querying
It doesn’t change your Time To Interact…
Query on client-side
Searching in 180.000 user takes up 500 ms with a classic AJAX request to database
Search on client-side (<50ms) = instant!
10x faster —> User experience 1000x better!
Where to store client-side?
MVC framework: Backbone, Angular, Ember, …
Store in models
Persist in LocalStorage to reduce startup time and across pages
example: news ticker
Data changes in realtime
Don’t kill your server polling for data
Use websockets or long-polling
Use a fast database with pubsub: redis, mongodb, …
Clients subscribe for updates
fast database + smart database
Use 2 databases
Fast database: redis.io, mongodb, … store things you stream to client
Smart database: mysql, postgresql, … store everything (also in realtime database)
Write to both database
Read from fast database = cache for slow database
Node.js = javascript
node.js + socket.io + redis.io
Super easy to setup!
You don’t need to be a back-end engineer, it’s just javascript that you need to copy-paste
Front-end developers can deliver a fast front-end if they master this part of the app
All the cross-browser shit is already solved
socket.io with node.js
!
“really, it’s just javascript,
dude”
socket.io client-side
!
also just javascript :-)
Conclusion
Not the websockets make your app fast
Avoiding AJAX calls to a slow database do!
Store all data client-side, do your queries client-side
Node.js meetup
Questions?
!Bert Wijnants end2end engineer @ Mobile Vikings
@bertwww www.newpage.be