►
Description
A Pub-Sub Architecture to Promote Blockchain Interoperability - Sara Ghaemi, TELUS
The maturing of blockchain technology leads to heterogeneity, where multiple solutions specialize in a particular use case. While the development of different blockchain networks shows great potential for blockchains, the isolated networks have led to data and asset silos. Blockchain interoperability solutions allow blockchains to support asset and data transfer, resulting in the development of innovative applications. This work proposes a blockchain interoperability solution for permissioned blockchains based on the publish/subscribe architecture. We implemented a prototype of this platform to show the feasibility of our design. We evaluated our solution by implementing example networks using Hyperledger Besu and two different versions of Hyperledger Fabric. We conducted a performance analysis of the whole network that indicates its limits and bottlenecks.
To learn more about Hyperledger, the open source community focused on developing a suite of stable frameworks, tools and libraries for enterprise-grade blockchain deployments. Which serves as a neutral home for various distributed ledger frameworks including Hyperledger Fabric, Sawtooth, Indy, as well as tools like Hyperledger Caliper and libraries like Hyperledger Ursa click here: https://www.hyperledger.org/
Session Details & Slides (if available)- https://sched.co/j3cA
Access All Sessions: https://events.linuxfoundation.org/hyperledger-global-forum/program/schedule/
----
Hyperledger – Open Source Blockchain Technologies
Hyperledger is an open source community focused on developing a suite of stable frameworks, tools and libraries for enterprise-grade blockchain deployments.
It serves as a neutral home for various distributed ledger frameworks including Hyperledger Besu, Fabric, Sawtooth, Indy, as well as tools like Hyperledger Avalon, Cactus and libraries like Hyperledger Aries, Ursa. Learn more about Hyperledger projects: https://www.hyperledger.org/use
Case Studies: https://www.hyperledger.org/learn/case-studies
Training & Certification: https://www.hyperledger.org/learn/training
Tutorials: https://www.hyperledger.org/use/tutorials
Webinars: https://www.hyperledger.org/learn/webinars
Events: https://www.hyperledger.org/events
Vendor Directory: https://www.hyperledger.org/use/vendor-directory
Subscribe to the Hyperledger Newsletter: https://www.hyperledger.org/newsletter
Follow-us on Twitter @Hyperledger
Learn about Hyperledger Membership: https://www.hyperledger.org/about/join
#Hyperledger #HyperledgerGlobalForum2021 #Blockchain
A
Okay,
I
think
we
can
get
started
hello.
Everyone
welcome
before
I
start
my
presentation,
I
just
wanted
to
say,
feel
free
to
type
in
in
the
chat
or
write
down
your
questions
in
the
q.
A
I
have
the
platforms
page
on
my
other
monitor
and
I
will
be.
I
will
be
trying
to
monitor
it
during
my
presentation,
great
so
before
I
get
started.
A
Today,
I'm
first
going
to
talk
a
little
bit
about
blockchain
interoperability
and
give
you
some
background
on
the
on
that
whole
thing,
and
then
I'm
going
to
tell
you
a
little
bit
about
the
latest
project
that
I've
been
doing
on
this
topic.
The
project
is
called
a
pops
up
architecture
to
promote
blockchain
interoperability
and
it
has
been
a
a
part
of
the
hyper
leisure
mentorship
program.
I
was
a
mentee
in
this
program
last
summer
and
I
had
the
opportunity
to
work
with
my
amazing
mentors,
sara
rouhani
raphael
belcher
and
professor
recruits
at
the
time.
A
A
So
before
I
tell
you
about
the
project,
I
want
to
tell
you
a
little
bit
about
why
blockchain
interoperability
is
important
and
why
we
need
it.
So
there
are
different
aspects
that
we
can
think
about
this
question.
First
of
all,
there
are
a
lot
of
blockchain
networks
being
built
around
the
world
for
specific
use
cases,
and
all
of
these
blockchains
are
working
independent
from
each
other
and
they're
isolated.
A
This
is
limiting
the
opportunities
that
this
technology
has
and
we
cannot
really
take
advantage
of
all
of
these
networks
when
they
cannot
work
together,
but
other
than
that
different
distributed.
Ledger
technologies
have
unique
features,
and
I
should
clarify
here
that
when
I
talk
about
distributed,
ledger
technologies,
I'm
talking
about
the
underlying
technology
like,
for
example,
hyperledger
fabric
is
a
dlt
and
hyperledger,
indeed,
is
another
one.
But
when
we
implement
a
network
based
on
each
of
these
technologies,
then
I'm
going
to
refer
to
that
as
the
blockchain
network
and
not
the
blockchain
technology.
A
So
when
I
say
different
distributed,
ledger
technologies
have
unique
features.
I
mean,
for
example,
hyperledger
indies
designed
for
digital
identities,
specifically,
but
hyperledger
fabric
is
a
more
general
solution
for
different
permission
use
cases.
So,
since
different
technologies
have
unique
features,
if
we
can
allow
interoperability,
we
can
actually
take
advantage
of
these
unique
features
of
different
technologies.
A
Instead
of
having
to
implement
everything
from
the
scratch
every
time
also,
there
are
distributed
applications
that
are
have
already
been
built
on
different
networks,
and
if
we
can
allow
interoperability,
we
can
use
that
and
the
underlying
and
the
technologies
that
they
have
all
of
the
features
that
they
are
providing
as
an
application.
We
can
use
that
in
other
applications
as
well,
instead
of
implementing
everything
in
each
application
separately.
A
Finally,
we
may
need
an
asset
from
another
network,
so
this
one
is
separate
from
the
previous
ones.
For
example,
let's
say
I
have
a
decentralized
identifier
or
did
on
a
hyperledger
in
the
network,
and
I
want
to
use
that
asset
in
a
hyperledger
fabric
network
or
any
other
network.
So
this
is
where
I
have
a
specific
asset,
and
if
we
can
allow
interoperability,
I
may
be
able
to
use
that
specific
asset
on
different
networks.
A
And
now,
when
we
think
about
interoperability,
there
are
different
scenarios
that
come
to
mind.
First
of
all,
we
may
need
to
swap
different
assets
across
networks,
let's
say,
for
example,
I
have
some
bitcoin
and
my
friend
has
some
ethereum
and
we
want
to
swap
these
between
networks.
So
this
is
when
we
say
this
is
an
asset
swap,
but
then
we
may
want
to
migrate
an
asset
from
a
network
to
another,
for
example.
A
If
if,
if
you
have
a
decentralized
identifier
on
one
hyperledger
in
the
instance,
I
may
need
to
migrate
that
to
another
hyperledger
in
the
instance
and
that
that's
when
the
second
point
is
that
basically
asset
migration
from
a
network
to
another
with
the
same
technology.
So
I'm
talking
about
two
hyperledger
in
these,
so
they
have
the
the
same
technology,
but
my
asset
is
on
one
of
them
and
I
want
to
migrate
it
to
the
other
one.
A
This
is
the
second
point
and
it's
different
from
the
third
one,
which
is
when
I
want
to
migrate
the
asset
to
another
network
with
a
different
technology.
Let's
say,
for
example,
I
want
to
migrate
that
same
asset
to
a
hyperledger
fabric
network,
so
this
this
has
a
little
bit
more
challenges
that
we
need
to
consider
compared
to
the
previous
one.
A
Another
scenario
is
when
we
want
to
query
data
from
another
ledger,
so,
let's
say,
for
example,
one
blockchain
has
weather
information
on
it,
and
I
have
this
application
that
I
want
to
use
that
weather
information.
So
I
can
al.
I
can
just
query
that
data
from
that
blockchain
I
don't
really
need
to
migrate
the
asset
or
swap
any
asset,
but
I
just
need
to
query
some
data
from
another
ledger
and
the
last
scenario
that
I
have
here
is
invoking
another
ledger.
A
So
let's
say,
for
example,
I
want
to
sell
some
product
and
there
are
two
blockchains.
One
of
them
is
responsible
for
the
financial
transactions.
Let's
call
that
the
bank
blockchain
or
the
banking
blockchain
and
there's
another
blockchain
that
is
responsible
for
delivering
the
product
and
it
handles
all
the
things
on
that
part.
A
A
So
now
that
we
have
some
idea
where
a
blockchain
interoperability
can
be
used
and
what
scenarios
there
are,
we
can
talk
about
different
categories
of
blockchain
interoperability.
One
of
the
most
famous
categorization
is
proposed
by
the
world
economic
forum.
If
you
scan
the
qr
code
on
this
page,
you
can
download
their
whitepaper
and
read
about
the
details.
A
Also
in
the
last
few
weeks,
I
think
it
was
two
or
three
weeks
ago.
I
watched
this
talk
that
dr
luke
riley
gave
on
this
categorization
and
he
goes
into
the
details.
I
really
recommend
this
talk.
If
you're
interested
on
this
topic,
you
can
access
it
using
the
hyperledger.org
website.
Slash
webinars,
I'm
just
going
to
give
you
some
overall
information
about
this
category,
because
there's
not
much
time
to
go
into
the
details.
A
So,
let's
start
with
cross
authentication
when
we
expect
both
of
the
parties
both
of
the
interoperability
parties
to
cryptic
cryptographically
authenticate
the
transactions.
That's
when
we
fall
under
the
cross,
authentication
and
there's
no
central
trusted
party
in
this
category
and
that
the
blockchain
networks
work
together
directly,
then
we
have
oracles
and
oracle
is
an
agent
that
enables
the
transfer
of
external
data.
A
Then
we
have
api
gateways
in
this
one.
Each
distributed
ledger
network
needs
to
implement
their
own
connector
and,
as
a
result,
these
interoperability
solutions
can
provide
access
to
a
lot
of
different
distributed,
ledger
networks,
and
the
reason
is
that
each
of
the
networks
separately
is
implementing
their
own
connector.
A
Another
categorization
is
proposed
by
my
mentor,
rafael
butcher.
He
also
gave
a
talk
a
few
days
ago.
I
think
two
days
ago
in
the
hyperledger
global
forum,
and
you
can
scan
the
qr
code
on
this
page
to
download
the
research
paper
that
he
has
written
on
this
topic.
So
the
first
category
here
is
the
public
connectors.
A
Every
interoperability
solution
that
wants
to
connect
to
public
blockchains
can
fall
under
this
one.
Under
this
category
we
have
side
chains
here.
The
idea
is
to
delegate
the
responsibility
of
the
interoperability
to
the
side
chain
and
not
handle
it
on
the
main
chain.
Then
we
have
a
hash
log
time
time
contracts
here.
The
idea
is
that
we
do
cross-chain
atomic
operations
using
smart
contracts.
A
The
next
category
is
the
hybrid
connectors
here.
Every
interoperability
that
wants
to
connect
a
private
and
a
public
blockchain
together
falls
under
this
one.
We
have
trusted
relays
here.
Trusted
relays
are
trusted
parties
that
redirect
transactions
from
one
blockchain
to
another.
Then
we
have
blockchain
agnostic
protocols.
A
These
solutions
allow
arbitrary
distributed
ledger
technologies
to
interoperate
by
providing
a
blockchain
abstraction
layer.
So
you
don't
you
don't
even
know
what
the
technology
behind
that
is.
You
use
this
blockchain
agnostic
protocol
to
interact
with
it,
no
matter
what
the
blockchain
is,
then
we
have
blockchain
migrators
here.
The
idea
is
to
migrate
a
state
of
a
blockchain
to
another,
and
finally,
we
have
blockchain
of
blockchains
here.
A
A
So
here
we
have
a
broker
blockchain
that
comes
in
the
middle,
and
it
has
two
smart
contracts.
It
has
the
connector
and
the
topic
smart
contract,
the
connector
smart
contract
is
responsible
for
handling
all
the
connections
to
different
blockchains
and
the
networking
and
everything
the
topic.
Smart
contract
holds
the
information
about
the
assets
that
are
being
transferred
or
the
information
about
that
asset
that
is
being
transferred,
so
imagine
a
source
and
a
destination
network
that
want
to
work
together.
A
We
call
the
source
network,
the
publisher
and
the
destination,
the
subscriber
for
each
of
these
blockchains
to
be
able
to
interact
with
our
platform.
They
need
to
implement
a
connector
smart
contract
when
they
do
that
they
can
use
the
connector
to
enroll
in
the
system
and
after
the
enrollment
is
done,
they
can
start
interacting.
A
A
It
depends
on
the
use
case,
but
the
main
idea
is
that
I
mentioned
we
have
two
smart
contracts:
the
connector
and
the
topic
smart
contract
on
our
broker.
Blockchain.
I
want
to
tell
you
a
little
bit
about
different
functionalities
that
they
support.
So
here
we
have
the
init
ledger
function.
That's
that's
a
standard
function
that
all
the
smart
contracts
in
fabric
have
and
that's
basically
the
function
that
runs
when
you
initiate
the
smart
contract.
A
Then,
if
you
look
at
the
connector
smart
contract,
we
have
create
blockchain.
This
function
is
used
every
time
a
new
blockchain
wants
to
enroll
in
the
network,
and
then
we
can
use
the
unique
id
of
that
blockchain
to
query
information
about
it,
and
we
can
also
query
all
the
blockchains
that
are
on
the
network
on
the
topic:
smart
contract,
the
publisher
can
create
a
topic,
and
then
the
unique
id
of
the
topic
can
be
used
to
query
information
about
that.
A
A
We
implemented
the
broker
blockchain
using
hyperledger
fabric
version
2.2,
and
I
will
talk
about
why
we
used
fabric
for
this
one.
We
used
hyperledger
caliper
to
analyze
the
performance
and
hyperledger
explorer
to
monitor
the
performance
of
our
network
and
for
the
publisher
and
subscribers.
We
implemented
these
in
different
technologies
and
different
versions
of
fabric,
because
we
wanted
to
show
that
this
could
eventually
be
used
with
other
permission
blockchains
as
well,
so
we
implemented
one
publisher
using
fabric
version
2.2
and
two
subscribers
using
fabric
version
1.4
and
another
in
hyperledger
bezu.
A
A
Here
you
can
see
four
windows,
the
top
left
one
is
the
broker.
The
bottom
left,
one
is
the
publisher
and
the
two
right
windows
are
the
subscribers.
The
top
one
is
fabric
subscriber
the
bottom
one
is
the
bezel
subscriber.
So
the
first
thing
I
want
to
do
is
to
query
all
the
topics
on
the
network.
I
just
want
to
make
sure
that
there
are
no
topics,
because
I'm
just
starting
the
demo-
and
I
want
to
do
the
same
thing
on
publisher-
to
make
sure
there
are
not
any
topics
there.
A
Then
I
want
to
create
a
new
topic
from
the
publisher
network
and
I
can
I
will
give
it
a
name
first
topic
and
a
message,
initial
message,
and
I
expect
that
this
topic
gets
created
on
the
publisher
and
on
the
broker.
So
I'm
going
to
query
again
on
the
publisher.
We
can
see
that
the
topic
has
been
created
and
if
you
query
the
broker
we
can
see,
the
topic
has
been
created
with
a
unique
id
and
the
list
of
subscribers
is
empty
right
now.
A
A
A
A
A
Okay,
I
mentioned
earlier
that
we
use
hyperledger
caliper
to
analyze
the
performance
of
our
network,
so
these
are
the
results.
What
we
did
was
that
we
changed
the
transaction
send
rate
which
is
shown
on
the
top.
We
changed
the
send
rate
throughout
time
and
we
monitored
the
throughput
and
the
average
latency
for
up
for
all
the
functionalities
that
our
broker
blockchain
supports.
A
There
are
a
lot
of
details
here
in
this
plot,
but
one
thing
that
I
want
to
mention
is
that
the
publish
to
topic
functionality,
which
is
the
purple
one,
that's
actually
our
bottleneck.
We
can
see
here
that
we
couldn't
even
increase
the
stand
standard
as
much
as
we
did
for
the
other
functionalities
and
the
throughput
gets
gets
limited
really
fast
and
the
average
latency
increases
to
up
to
80
80
seconds.
A
A
A
But
we
can
work
on
adding
support
for
other
permission
blockchains
as
well,
but
any
blockchain
as
long
as
they
implement
a
connector.
They
can
connect
it
to
this
network.
So
it's
not
like.
We
have
to
do
anything
on
the
broker
side,
it's
mainly
on
the
publisher
and
subscriber
side,
and
then
we
can
add
an
access
control
layer
right
now.
Everyone
can
see
and
access
all
the
topics
on
the
network.
We
can
add
another
layer
of
control.
A
For
example,
publish
the
publisher
network
can
control
who
can
access
the
topics
that
they're
publishing
to
and
we
can
work
on
enhancing
the
performance.
So
we
already
know
the
bottleneck
of
our
network
is
the
publish
to
topic
functionality.
So
we
can
work
on
improving
that
and
making
a
little
bit
more
performant
and
we
can
work
on
enhancing
the
transaction
verification
right
now,
we're
not
doing
much
verification
other
than
what
fabric
does
in
its
default
version.
A
A
So
hello,
everyone,
hello,
brian,
hello,
tomaso
sandy.
I
am
not
sure,
like
oracles
and
notaries
that
I
talked
about,
they
are
in
the
categorizations
that
are
proposed
by
the
by
rafael,
belcher
and
by
the
organization
that
I
talked
about.
So
these
are
not
concepts
that
I'm
proposing
here,
so
they
could
come
from
corda,
but
I'm
not
sure
about
that.
A
This
so
the
question
is:
do
you
wait
that
all
the
subscribers
commits
the
operation
to
their
blockchain
prior
to
removing
the
posted
message?
So
we
don't
remove
the
message?
Actually,
the
message
is
going
to
be
there
as
long
as
the
publisher
wants
it
to
be
there,
when
the
message
on
that
topic
is
changed,
we're
going
to
replace
it
with
a
new
one.
So
if
the
subscribers
get
the
new
version,
so
that
could
happen
like
the
before
they
get
the
older
version.
A
new
version
comes
in,
but
they
basically
need
the
newer
version.
A
So
they
should
be
good.
Assuming
a
subscribe
to
a
topic.
Can
they
get
the
notifications
automatically?
Yes,
they
will
get
the
notifications
automatically
so
that
that's
the
idea,
the
a
does
not
need
to
query
anything
and
that's
the
whole
point
of
using
the
publish
subscribe
architecture.
We
don't
want
the
subscribers
to
keep
checking
and
keep
querying
the
publisher
to
get
the
latest
version,
but
the
broker
will
let
everyone
know
of
the
change.
A
They
can
use
this
platform
because
they
don't
need
to
keep
querying
it
and
every
time
it
changes.
Let's,
let's
think
about
the
weather
example
again.
So,
for
example,
I
want
to
have
an
application
that
does
something
based
on
the
weather
change.
So
by
default
I
have
to
keep
checking
the
weather
every
time.
I
have
to
query
it
to
see
when
it
changes
how
it
changes,
but
in
this
platform
you
can
just
subscribe
to
that
and
you
can
get
notified
every
every
time
it
changes.
A
So
the
question
is:
could
you
talk
a
little
bit
about
your
roadmap
for
adding
other
blockchains?
Are
you
mostly
focused
on
those
within
the
hyperledger
umbrella
or
looking
at
others
as
well?
So
our
platform
is
open
source
and
all
of
our
code
is
open
source
and
we
would
appreciate
anyone
who's
interested
in
adding
adding
different
blockchains
to
our
network,
we're
not
limited
to
hyperledger
at
all.
A
A
Okay,
mohan,
your
question
is,
I
mean,
could
a
transaction
occur
on
fabric
and
then
a
notification
can
trigger
a
payment
in
bezu?
Yes,
this
is
totally
up
to
the
subscribers.
So,
for
example,
if
we
have
a
publisher
that
is
in
fabric
as
it's
written
in
fabric
and
we
have
a
subscriber
that
is
written
in
bezu,
something
happens
on
the
fabric,
the
bezel
gets
notified
it's
up
to
the
bezel
network,
what
they
want
to
do
with
that
notification,
so
they
can
trigger
a
payment
if
they
want,
they
can
add
it
to
their
application.
A
Subscriber
so
right
now,
okay,
so
let
me
just
read
the
question
also:
does
data
for
data
flow
bi-directionally
from
fabric
to
bezel
and
back
or
is
bezou
currently
only
able
to
operate
as
a
subscriber,
so
currently
fabric
can
be
both
a
subscriber
and
a
publisher,
but
bezu.
We
currently
only
have
a
subscriber
connector
implemented
for
it.
A
So
the
question
is:
how
do
you
guarantee
to
the
subscriber
that
the
transaction
went
through
the
consensus
protocol
and
is
correct?
That
is
a
great
question
and
that's
that's
one
of
the
points
that
I
had
from
for
the
future
work.
So,
basically
right
now
we're
just
using
the
default
verification
of
all
of
our
platforms.
A
A
Basically,
great,
I
think
I've
covered
all
the
questions
and
we're
out
of
time.
Thank
you
so
much
all
for
joining
and
feel
free
to
contact
me
reach
out
to
me
I'll,
be
happy
to
have
a
discussion
on
this
or
anything
else
related
to
blockchain.
Oh
okay!
Let
me
just
get
this
last
question
that
I
got
in
the
q
a
how
do
we
choose
who
acts
as
publisher
node
in
a
network,
so
the
blockchains
that
want
to
participate?
They
choose
whether
they
want
to
act
as
a
publisher
or
a
subscriber.