1. From
Web
sites
to
Web
apps
in
Rails
Ambert
Ho
*all
images
were
has7ly
ripped
off
the
internet
and
belong
to
their
respec7ve
owner

2. What
is
a
web
site
vs.
web
app?
• Content
consump7on
vs.
interac7on?
• Facebook
and
TwiCer
blur
the
line

3. Emerging
importance
of
‘real7me’
I
use
this
term
loosely
since
‘real7me’
has
predefined
meanings
in
terms
of
RTOS
• Applica7ons
should
change
state
regardless
of
interac7on
• Even
for
content
sites:
• TwiCer
and
Google
News
update
themselves
while
you
look
at
it
• Same
with
Facebook
wall,
plus
FB
no7fica7ons
• Previously,
‘real7me’
primarily
used
for
chat

4. How
does
it
work?

5. What
is
comet/reverse
ajax/ajax
push?
(‘push’
data
to
client)
• Long
polling
• Websockets
• (flash
sockets
too)

6. Details:
how
to
actually
go
about
doing
this?
• To
bolt
onto
Rails
you
need:
1. A
real7me
endpoint
(more
on
this
later)
2. Way
to
communicate
with
that
endpoint
3. Clientside
code
organiza7on
to
process
what
happens
“Gimme
a
real
example”

7. Juggernaut
• hCps://github.com/maccman/juggernaut
• Used
to
be
EM,
now
uses
Node.js
Juggernaut
logic
Redis
Gem
for
interface
Node.JS
Socket.IO
(server)
Rails
Socket.IO
(client)
Your
JS
Client

8. Event
Loop
(For
the
real7me
endpoint)
• Why
not
use
Rails
all
the
way?
• Your
web
server
spins
up
a
worker
pool
of
en7re
Rails
instances
• #
persistent
connec7ons
limited
by
#
Rails
instances
that
fit
in
memory
• spinning
up
Rails
also
takes
7me
• BeCer
with
REE
and
CoW
• Event
loops
excel
at
I/O
bound
tasks*
• Lot
of
simple
web
stuff,
par7cularly
*It’s
more
complicated
managing
connec7ons
like
with
‘real7me’,
If
you
want
to
know
why
is
I/O
bound
research
concurrency
on
JVM

9. Review
on
‘what
does
what’
Rails,
using
the
Redis
gem
or
some
Do
it
OOB?
(Net::HTTP
is
wrapper
like
the
Juggernaut
gem,
blocking)
publishes
to
Redis,
and
since
Node.js
is
subscribed
it
gets
the
message,
which
it
boots
to
the
client
through
Socket.IO
–
the
client
then
uses
a
framework
(like
Backbone.js)
to
work
with
the
piece
of
data.
• Backbone
is
designed
towards
working
with
serialized
remote
data

10. Alterna7ves
• Pusher
• Don’t
have
to
setup
Node
and
Redis
• Considera7on
with
websockets
(HTTP
1.1)
and
servers
proxied
behind
NGINX
• benefits
of
having
it
run
as
a
service,
but
costs
$$$
• Run
the
en7re
app
in
Node.js
• LinkedIn
mobile
is
like
this
• Consider
hos7ng
(Dotcloud,
Heroku,
NodeJitsu)

11. Slides
http://www.slideshare.net/ambertch
Contact
ambert@opzi.com
Discussion/Questions?