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From YouTube: [Swarm Mini Summit] Swarm Feeds Introduction
Description
Javier Peletier - Epic Labs
Swarm is a content-addressed network, so when you upload something, that content can be retrieved back by providing its hash. Therefore, to host a changing website on Swarm, you need to store the website’s hash in a ENS contract to have it resolve the name to that hash so users can find your content. Thus, every website update requires an ENS on-chain transaction.
This may be fine for websites or Dapps that don’t change often, but certainly not OK for most applications. What if we provided a way for cheaply and quickly update content and also allowed the users and Dapps themselves to create and update content dinamically? What sorts of applications would this enable?
Enter Swarm feeds
Swarm feeeds are a powerful but little-known feature that enables Dapp developers to write applications that allow users to find, update and retrieve content, proving ownership with a signature, but without having to resort to interacting with a smart contract. In this talk, we would like to introduce developers to this feature, how it works, strengths and weaknesses, its simple API and how to get started using feeds with the command line, via HTTP API and even directly in the browser!
Biography - Javier Peletier
Javier Peletier is the CTO and cofounder of Epic Labs, an innovation center in Spain specialized in the Media industry and Blockchain techologies.
At Epic Labs, he is currently leading the Ethergit project, aimed at providing tools to decentralize open source once and for all, while contributing to making Ethereum/Swarm more powerful. On the latter, he worked during this year to help improve Swarm MRUs and make them more accesible to the web developer and easier to consume.
Prior to Epic Labs, Javier worked at Akamai, the first Internet content-delivery network as Services Director and Engineering Director, learning how content moves over the Internet reliably and at scale, working with engineers all over the world and helping deliver global streaming events such as the World Cup.
Javier is one of those passionate engineers who has been in the computing world since he was 5 and learned to code in his 48K, 8-bit ZX-Spectrum and hooked on the Internet since 1995. He enjoys designing and building scalable architectures and systems with the best team of engineers. Lots of war stories and anecdotes to share!
A
B
Thank
you
very
much.
Everybody
for
the
opportunity
to
present
today
I'm
going
to
be
introducing
storm
feeds.
I
see
that
in
many
of
the
presentations
he's
been
mentioned,
as
a
building
block
for
something
else,
and
that's
great,
also
I'm,
just
representing
the
the
work
that
the
foreign
team
has
has
done
up
to
to
get
to
this
point
and
and
then
I
will
help
move
this
module
I
had
a
little
bit
too
so
yeah
just
a
little
bit
about
me.
B
My
name
is
Javier
Pelletier
I'm,
the
CTO
at
epic
labs,
and
we
are
a
three
year
old
company,
Innovation
Center
in
Spain.
Just
a
little
bit
about
the
agenda
today,
a
little
bit
about
the
pig
laughs,
then
we're
going
to
be
talking
about
what
are
our
feeds?
How
does
form
fits
work?
How
do
how
do
I
use
form
fits
and
then
an
API
introduction?
So
you
guys
get
familiar
with
with
how
it
works?
How
what
are
the
things
that
are
underneath
and
then
a
few
demos
that
I
think
will
help
illustrate
this
better:
okay,
okay!
B
So,
just
a
little
bit
about
about
epic
laughs,
we're
a
team
of
25
engineers
in
Madrid
in
Spain,
with
a
sovereign
ovation.
Center
will
help
medium
to
large
companies,
innovate,
we're
experts
in
video
and
media
over
the
internet
and
calling
a
machine
learning
applied
to
video
technologies,
but
also
we
have
a
part
of
our
company
that
you
get
blocked
in
consulting
services
and
training,
we're
building
also
a
circuit
which
is
a
tool
to
decentralized
open
source
collaboration
and
in
starting
with
this
project.
B
B
Okay,
it's
cheaper
than
DNS
another
thing,
another
definition:
anyone,
okay
I'll,
try
because
I
don't
think
we
start
doing
the
work
and
then
we
try
to
define
it.
Okay,
so
I
think
we
could
define
from
pieces
and
microblogging
platform
or
a
microblogging
platform
building
block
okay
and
as
such,
it
allows
you
to
post
updates
about
a
certain
topic.
Okay,.
C
B
You
can
also
read
other
people's
updates
about
that
particular
topic.
Okay,
so
the
focus
of
fits
in
here
is:
do
one
thing
and
doing
very,
very
well.
Okay,
so
think
about
a
microblogging
platform,
or
you
can
post
updates
and
you
can
read
other
people's
updates.
Okay,
we
want
a
more
academic
definition
of
bit
of
this.
I
would
go,
I
will
offer
for
this
one
it
could.
It
could
also
be
a
key
value
store,
okay,
where
each
user
can
only
write
to
their
own
key
space.
B
Okay,
so
of
all
the
possible
keys,
you
will
only
be
allowed
to
write
to
some
of
them.
Okay,
and
you
can
call
that
that
key
space,
your
own
okay,
but
you
can
read
yours,
another
user's
key
space.
Okay,
so
you
could
consider
from
feels
like
a
key
value
store
somehow,
but
it
also
has
the
property
that
you
can
retrieve
older
versions
of
a
value.
Okay,
if
you
provide
a
time
parameter,
you
can
also
read
all
values.
Okay,
so
how
do
we
address
fits
how
we
will
refer
to
a
feed?
B
Okay,
I
feel
this
address
only
with
two
things.
Remember
this
only
two
things:
the
user's
aetherium
address:
that's
the
only
one
of
the
things
that
you
need
and
you
also
need
a
topic
which
is
a
32
byte
array.
Anything
you
consider
okay,
and
this
is
a
more
go
line,
definition
of
what
a
fish
just
two
things:
a
topic
and
a
user
others.
So
there's
one
feed
per
topic
per
topic
per
user,
so
infinite
possible
feats.
Okay,
just
imagine
that
you
hate
you
have
a
Twitter
account
for
every
possible
topic,
and
actually
people
do
that
right.
B
B
You
know
keep
things
separate,
okay,
so
imagine
that
you
have
like
this
possibility
of
having
a
like
a
like
a
Twitter
account
for
every
possible
topic.
Okay,
so
what
are
the
things
or
benefits
the
things
that
you
can
do
with
feeds?
You
can
instantly
alter
content
in
swarm
without
Unchained
transactions?
Okay,
as
I
just
mentioned
before,
you
can
enabled
apps
to
persist,
content
very
easily
okay,
so
you
have
adapt.
It
runs
from
maybe
100
percent
on
HTML,
and
you
want
that
application
to
save
something
and
then
retrieve
it.
B
B
Okay,
interestingly
also
I
think
it
also
enables
the
centralized
Internet
of
Things,
and
we
will
see
that
in
a
few
slides.
So
just
let's
look
at
an
example
of
how
this
will
look
like
okay,
so
imagine
that
we
have
three
users.
Each
of
them
has
three
I
mean
each
of
them
has
their
own
address?
Okay,
and
then
you
also
have
topics.
Okay,
a
topic
could
be
avatar
like
profile,
picture,
kind
of
thing,
local
weather
or
website.
B
Okay
and
some
of
the
users
start
posting
updates
to
that
particular
user
is
gonna,
be
posting
an
update
on
on
on
her
avatar
or
his
rabbit,
his
avatar
okay
and
they
they're
gonna,
say:
okay,
my
avatar
is
this
picture?
Okay,
so
this
this
means
that
if
you
query
the
field
giving
giving
the
user
address
and
the
topic
you're
gonna
get
the
image
that
the
user
posted.
Okay-
if
you
worry
another
illusion
and
a
different
topic,
you're
gonna
get
the
corresponding
the
corresponding
value.
So
that's
what
I,
what
I
meant
when
I
was
saying
that
is?
B
It
looks
like
a
key
value
store.
Okay,
you
can
store
something
on
the
rocky
and
retrieve
it
back.
So
what
happens
the
next
day,
for
example,
somebody
makes
an
update,
you
know,
user,
a
changes,
the
profile
picture.
Okay,
we
can
now
worry
the
same
thing.
You,
sir,
on
the
same
topic,
we're
going
to
get
the
new
the
new
picture.
Okay,
but
if
we
incorporate
a
time
parameter
and
say,
for
example,
that
I
want
the
profile
picture
as
if
it
was
yesterday.
B
Okay,
I'll
get
the
older
one
okay,
so
it's
a
key
value
store
with
the
time
component
of
being
able
to
retrieve
an
old
version
referring
to
it
by
a
timestamp,
okay,
okay.
So
what
are
the
things
that
you
need
to
to
post
or
read?
Reading
a
fee
happy
so
to
a
certain
feed.
You
need
two
things.
As
we
said
before,
a
you
need
a
private
key
to
sign
your
update
and
you
need
a
topic.
Okay
to
read.
You
need
the
user
system
address
and
the
topic.
B
Okay,
so
I'm
repeating
this,
because
it's
important
to
to
get
the
concept
as
it's
as
simple
as
that.
Okay,
and
if
you
want
the
other
post,
you
need
a
timestamp
okay.
So
what
is
the
topic?
The
topic
is
just
a
32
byte
array
and
how
you
get
to
that
array
is
completely
up
to
you.
Okay,
that
topic
could
be
a
hash
of
something
okay.
B
So,
for
example,
if
it's
known
that
people
post
their
profile
picture
to
the
avatar
topic,
then
once
we
see
user
address,
I
could
see
that
user
address
then
get
the
word
avatar,
okay
and
then
retrieve
the
picture.
For
example,
if
I,
if
I
had
a
wallet,
application
and
I
see
that
incoming
transaction
that
somebody
paid
okay,
I
could
do
a
look-up
on
that
address.
Okay
with
a
particular
topic,
maybe
user
information
or
something,
and
then
I
could
retrieve
information
about
that
particular
user.
B
Okay
I
know
in
their
address
and
a
set
of
well-known
topic
names,
for
example.
Okay,
let's
talk
about
the
feed
payload,
what
are
the
things
that
you
can
put
on
a
field?
Okay,
a
feed
payload
is
limited
to
three
thousand
nine
hundred
and
sixty
three
whites.
Okay,
there's
a
constant
in
code
that
will
give
you
that
value.
B
Okay,
that's
because
the
feed
is
just
a
strong
chunk
which
is
4k,
and
then
we
have
to
add
some
headers
and
stuff,
so
that
leaves
it
to
3163
bytes,
but
in
general
you
will
want
to
post
to
the
field
the
hash
of
the
actual
content,
not
the
actual
content,
because
actual
content,
you're
gonna
be
limited
to
the
three
thousand
nine
hundred,
sixty
three
bytes.
So
usually
you
will
upload
something
to
swarm
the
roll
our
way,
okay,
get
the
hash
and
put
the
hash
in
there,
and
they
have
plenty
of
space
to
put
it
there.
B
Okay,
okay,
there's
also
a
concept
of
feed
manifest
okay:
this
is
somewhat
optional
to
deal
with
feeds.
Okay,
a
manifest
is
just
a
JSON
that
contains
the
bare
minimum
information
to
look
up
a
fit,
and
that
is
again
that
usually
aetherium
address
and
a
topic.
Okay
and
this
session
can
be
uploaded
to
the
regular
in
a
regular
way.
Okay
like
form
up,
and
then
you
obtain
a
hash,
okay
that
you
can
use
within
in
enos
or
BCC.
B
This
is
the
how
it
looks.
Okay
is
just
a
topic
and
a
user-
that's
that's
all
got
in
there
and,
for
example,
in
this
case,
what
we're
having
here
is
the
word
website,
xn
coded
writer,
okay,
so
that
topic
would
be
about
website
information.
So
how?
How
does
this
work
with
DNS?
Okay?
So
before
we
have
feeds?
B
What
we
had
to
do
is
get
some
content,
okay
and
do
swarm
up
okay,
and
we
would
receive
the
hash
of
a
content
manifest
okay
and
then
what
we
would
do
with
that
hash
is
do
a
NS
to
answer.
If
you
don't
transaction
and
pay
the
fee
and
have
that
has
be
stored
in
the
blockchain
under
that
name,
for
example.
So
it
means
that
when
I
want
to
update
I
need
to
again
I
need
to
upload
the
content
as
before.
Okay
I
get
a
new
content
manifestation.
B
Okay
and
then
I
have
to
do
a
transaction
to
change
that
pointer
and
then
this
would
be
forgotten.
Maybe,
but
the
content
I
mean
the
site
will
point
to
the
new
to
the
new
content.
Okay,
that's
how
we
work,
how
it
works
without
without
fits
with
from
feeds.
You
first
need
to
upload
the
content.
You
get
a
condom
manifest.json,
you
publish
this
on
their
feet.
Okay
and
then
you
take
that
trash
and
you
put
it
on
ens.
B
Okay,
you
have
to
do
one
one
transaction
used
to
sarah
pianist,
but
the
the
benefit
is
that
subsequent
updates
will
not
have
any
transaction
course.
So
you
will
have
this
and
then
you
want
to
put
new
content.
You
upload
a
new
content,
get
a
new
manifestation
and
then
change
that
pointer
at
this
level.
Okay,
which
means
that
there's
no
interaction
with
the
ear
with
Els,
and
that
means
no
transaction
cost
in
that
sense.
B
Okay,
take
a
look
also
at
the
HTTP
API,
to
read,
updates
to
read
an
update.
We
said
before
that
we
listened
only
two
things
that
we
need
is
the
user
address
and
the
topic,
so
the
API
is
when
I
tell
you,
I
need
a
a
topic:
okay
and
I
need
a
user
address.
Okay,
and
if
there's
an
update,
okay,
you
will
get
a
binary
response.
B
Http
response,
okay
to
post
updates,
it's
a
little
bit
more
work,
but
first
you
need
to
learn
the
feed
stars
and
you
can
retrieve
it
with
this
with
this
extra
parameter.
Okay,
and
it
will
tell
you
what
is
the
field
starts
at
this
point?
Okay
and
then,
with
that
fee,
the
stars,
you
build
this
big
query,
string
and
post
the
updates
through
that.
Okay,
the
complex
thing
about
this,
mostly
is
calculating
the
signature.
I
will
try
to
help,
explain
that
in
next
slide,
but
this
is
work
in
progress
to
simplify
that
single
Signum
process.
B
So,
in
the
go
API
to
read,
updates
you
need
to
construct
a
query
object.
Okay,
when
you
indicate
the
user
and
the
topic
okay,
then
you
just
call
a
client
query
feed
with
that
query
object,
and
it
will
give
you
a
I
or
either
with
with
all
that
information
with
the
information
that
is
posted
to
post
updates.
You
need
to
use
that
query
object
to
get
a
request,
object
in
which
you
are
going
to
be
able
to
attach
the
data
that
you
want
to
publish
and
sign
it.
B
Okay,
and
with
that
you
can
call
update
field.
So
all
this
is
more
or
less
is
abstracted
out
in
the
API,
so
signatures,
which
is
a
hot
topic
okay.
So
this
is
the
shape
that
a
feed
payload
has-
and
this
is
something
that
we
have
to
sign
so
internally.
It
means
that
we
have
a
version.
We
have
the
topic,
we
have
the
etherium
address.
We
have
the
time
at
which
we're
posting
frequency
and
then
the
data
that
we
want
to
post,
and
that
is,
we
have
to
calculate
an
ECDSA
signature
out
of
that.
B
Okay,
the
go
API
does
it
for
you.
There's
some
JavaScript
snippets
floating
around
that
do
this,
okay
and
hopefully
at
the
end
of
the
DEF
CON
I,
can
publish
a
C++
version
of
this
okay,
but
this
is
posted
in
the
we'll,
be
posting
this
to
the
commendation.
So
that
is
easier
to
understand
how
to
implement
nesting
letter
for
feet.
Okay,
so
we're
going
to
be
doing
a
demo.
Okay,
step-by-step!
A
B
Well,
as
I
said
before,
hopefully
we
can.
We
can
use
this
this
tool
as
a
building
block
for
those
applications
that
will
be
easier
to
use
right,
nobody's
weird
used
to
just
opening
up
our
phone
and
using
some
messaging
service,
for
example,
that
is
already
built.
Okay,
this
would
be
a
building
block
that
will
allow
us
allow
us
to
build
this
application
in
a
more
decentralized
way,
because
there
are
regular
tools
that
we
have
like
whatsapp,
for
example,
are
owned
by
by
a
big
company
right.
B
B
A
B
C
C
A
C
B
C
B
C
B
A
A
B
And
that's
actually
right:
I
didn't
update
the
field.
I
just
created
the
manifest
ok,
so
I
need
to
I
need
to
update
the
money.
I'm
gonna
update
the
feed
I
created
a
manifest,
but
I
need
to
really
post
the
picture.
Now
we
had
before
so
just
back
again
get
the
house
of
the
picture.
Ok
and
now
we're
gonna
be
updating
not
creating.
C
A
C
C
B
B
B
A
B
B
The
way
this
is
working
is
that
this
device
is
just
reading
the
temperature
from
a
sensor
packages
in
to
feed
forces
to
swarm,
and
then
this
web
application,
as
you
can
see,
is
hosted
on
from
gateways
on
inform,
is
just
reading
that
field
to
plot
this
graph,
okay,
and
also
since
real-time.
You
know
this
is
publishing.
Information
is
getting
Stein
to
get
new
new
data
points.
Okay,
tricky
right,
that's
the
sensor
with
my
finger
and
we
wait
a
little
bit
the
temperature
will
increase.
So
it's
always
saying
that
information
is
is
being
moved.
B
Know
I
know:
my
sensor
is
just
not
good
all
right,
okay,
so
areas
of
improvement,
and
with
this
I
finish,
we
need
to
accelerate
that
lookup
algorithm.
So
some
of
the
bugs
that
you
have
seen
maybe
relate
too
late
to
that
we
need
to
simplify
how
to
sign
feet,
update
we
like
to
have
a
official,
yes,
client,
that
everybody
can
work
with
improve
the
HTTP
API,
which
has
complexities.
Okay
and
potentially,
you
know,
have
a
way
to
add
a
user
amount
point.