►
From YouTube: Chaincode deep dive with Node.js
Description
A recording of a Hyperledger Tech Study Circle session run by the Hyperledger Sweden meetup group on March 12, 2021. This is the 2nd part of their chaincode deep dive with Node.js and will walk through enabling CouchDb in Hyperledger Fabric 2.2 using the example of test-network.
More about the event is at: https://www.meetup.com/Hyperledger-Sweden/events/275744230/
----
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A
At
the
beginning,
I
would
like
to
give
you
a
short
overview
of
what
we
are
doing
today
and
I
will
represent
the
use
case
again
so
that
you
will
understand.
What's
going
on
in
this
example,
and
then
we
will
make
a
short
introduction.
What
is
the
state
database
so
that
we
know
what
we
mean
with
this
term
and
it's
always
good
to
know
also
from
the
perspective
of
and
favorite.
A
B
A
In
favor
kids,
so
that
we
have
a
so-called
state
database
and
by
default
and
in
all
sessions
until
this
session
today,
we
have
always
used
leveldb
and
that's
one.
That's
the
default
way
of
storing
a
state
state
of
an
asset,
but
favic
offers
also
a
secondary
and
did
this
with
couchdb?
That's
a
no
secret
database,
and
this
gives.
B
A
A
Here
on,
in
this
reference
section,
you
will
find
the
agenda
and
also
the
previous
agendas
and
also
upcoming
agendas
here,
and
here
is
also
the
link
to
the
support
material.
This
is
the
same
link
which
I
have
posted
to
the
chat
here
and
on
this
github
repo.
You
find
also
all
other
support
materials
from
the
previous
sessions
so
and
also
the
materials
which
maybe
you
need
for
today's
session.
So
when
you
have
missed
some
sessions
before.
A
B
B
A
A
Have
done
in
the
last
session,
the
implementation
of
this
chain
code
in
node
shares,
and
we
have
seen
that
how
large
this
container
image
would
be
if
you
try
to
use
this
chain
code
in
the
test
network
and
also,
we
have
seen
how
many
transactions
per
seconds
we
can
reach
with
a
simple
single
virtual
machine
on
digital
ocean
and
in
the
last
week
I
have
implemented
the
same,
the
same
chain
code
also
in
goling.
But
we
will
come
to
this
a
little
bit
later
when.
A
A
For
today's
session
and
in
the
last
session
we
have
seen
that
when
we
use
couch
when
we
use
level
to
be,
then
we
have
a
very
simple
scenario.
So
we
have
a
key
and
the
value
to
store
in
the
blockchain
and
the
key
is
only
a
is
always
a
string.
So
it's
a
string.
It's
a
number,
it's
a
number,
it's
a
unique
id
or
whatever,
but
it's
always
a
string
and
it's
always
unique.
So
one
single
transaction
has
only
one
unique
key
and
to
query
this.
A
But
here
is
just
another
slide,
so
it
somehow.
This
slide
summarize
a
little
bit
what
we
have
done
in
the
last
session.
So
to
give
you
a
better
overview.
So
here
is
our
data
model.
So,
as
we
have
seen
in
the
last
session,
and
then
we
have
used
this
standard
leveldb
database
and
with
this
technique
of
composite
key,
we
have
created
the
function,
get
commission
statement
per
year
month
and
when
we
have
used
this
function
then
we
have
to.
We
have
the
possibility
that
we
can
say.
A
Okay,
I
want
to
see
all
revenues
from
the
from
a
year
from
a
month
or
exactly
one
particular
transaction
so
and
ex-
and
in
this
in
this
way
so
and
with
couchdb.
Now
we
have
the
possibility
to
use
all
these
composite
key
queries
as
well,
and
we
can
extend
this
also
with
a
new
function
and
then
we
can
make
a
query
with
this.
We
have
this
defined
function
and
the
switch
special
selector
that
we
can
query
date
to
date,
so
we
can
say:
okay,
this
is
my
date
string.
A
Okay,
so
and
here's
the
slide,
so
what
is
a
state
database?
So
when
you
start
with
favorite,
then
you
have
to
know
some
little
basics
and
one
basic
is
that
everything
what
is
stored
in
favorite
is
an
asset.
So
an
asset
is
something
like
can
could
be.
Everything
could
be,
this
transaction
of
the
revenue
could
be
a
house
could
be
a
car,
could
be
a
nun,
find
your
token
whatever
so,
and
could
also
be
only
a
string.
A
For
example,
yeah
could
a
string
or
it
could
be
a
data
object,
and
in
this
data
object
you
can
store
other
data
objects
and
so
on.
So
I
think
every
json
structure
you
can
compose
you
can
store
also
in
the
value
of
the
block
of
also
in
the
value
of
this
asset,
and
the
state
database
is
by
default
level.
A
Dp,
as
I
have
mentioned,
and
the
state
database
holds
also
the
last
the
last
version,
the
last
status
of
an
asset
so
and
that's
a
really
a
cool
feature
which
you
in
in
blockchain,
because
when
we
query
the
last
state
of
any
key,
then
we
are,
we
don't
have
to
query
the
whole
blockchain
and
the
blockchain
could
be
huge.
So
we
only
have
to
query
the
world
state
and
the
world
state
is
a
key
value
store
in
level
db
or
in
couchdb
and
our
other
histories
for
examples.
A
B
A
B
A
Yeah
how
you
can
enable
this
now,
so
that's,
I
think,
pretty
simple.
So
the
only
thing
what
we
have
to
do
is
we
have
to
include
the
new
docker
service
so
and
the
fabric
comes
with
an
image,
and
this
image
is
a
favorite
couch
to
be
here,
hyperledger
favorite
couch
to
be,
and
we
have
to
define
in
the
docker
compose
file
here
new
service,
and
there
are
some
some
some
points
to
notice
here:
the
environment.
A
So
this
is
important
that
we
set
an
couchdb
user
and
then
couch
to
be
a
password
and
yeah
and
a
couch
to
be
serviced
in
the
couch
container
name,
and
then
we
have
here
to
formulate
this
is
the
standard
part.
So
this
is
the
standard
part
for
one
coach
to
be
a
service,
and
we
have
to
make
sure
that
we
are
in
the
right
or
in
the
same
network
here
and
then
we
have
to
to
link
the
this
couch
to
be
container
to
the
corresponding
pier
container.
A
B
A
A
You
can
have
level
db,
but
when
you
use
the
example
like
like
today,
then
of
course
you
cannot,
you
can
only
use
the
couch
to
be
a
curious,
honest
on
the
pier
where
you
have
also
code
should
be
running
also
and
to
connect
this
this,
both
together
so
favorite
case
here,
two
environment
variables,
namely
core
electricity
state
database,
must
be
set
to
couch
to
be
here
and
then
this
couch
to
be
config,
couchdb,
address
environment
variable
here
must
must
point
to
the
service
name
couch
to
be
zero
and
the
corresponding
part.
Here.
A
A
A
B
B
B
A
I
think
this
is
a
good
idea
and
a
good
learning
to
see
how
we
can
use
also
an
nodejs
client
for
for
this
docker
dev
mode,
and
then
you
can,
I
think,
maybe
a
little
bit
easier
test.
Your
chain
code,
okay,
so-
and
here
you
see
the
the
web
ui,
yes
as
an
administrator
tool,
for
example-
and
here
you
have
to
replace
the
local
host
with
your
ip.
A
One
thing
what
we
can
do
also
with
this
type
of
queries
is:
we
can
have
an
order.
We
can
change
the
order,
so
we
can
make
a
simple
sort.
We
can
sort
in
two
directions
and
but
for
this
we
need
an
index
so
and
when
we
create
a
chain
code-
and
we
install
this
train
code,
then
we
have
provided
in
the
tranquil
folder
and
index
and
the
index
is
nothing
more
than
a
json
file,
and
this
here
is
the
json
file.
So
so,
and
here
we
can
define
the
index
fields.
A
So
what
we
want
to
index
and
to
query
is
the
revenue
timestamp,
and
we
can
do
this
and
then
we
here
define
this
field,
the
fields
we
can
have
multiple
fields,
fields
which
are
going
to
be
indexed
and
then
we
have
to
give
them
a
name.
So
the
index
revenue
time
set
name,
that's
the
name
of
the
index
and
then
here
this
type
property
is
json.
So
there
is
only
this
type
for
the
moment
and
the
dd
dock.
A
This
ddoc
property
is
optional
and
I
don't
know
exactly
for
what's
going
on,
but
maybe
when
you
change
the
index,
I
have
read
that
if
you
change
the
index,
then
you
have
to
use
this
one
but
yeah.
So
that's
the
only
important
part
here
is
that
you
see
the
structure,
so
you
have
to
on
your
chain
code
folder
in
the
root
of
your
chain
code
folder.
A
You
have
to
create
this
folder
structure
with
meta-inf
state
database,
couchdb
indexes-
and
here
you
have
this
put
in
this
json
document-
and
you
can
call
it
index
revenue,
and
this
is
the
content
of
this
index
document
and
when
we
install
this
chain
code,
this
folder
will
also
during
the
installation
process.
The
setup
will
see
that
there
is
an
index
and
will
install
this
index
in
the
train
code
in
the
culture
to
be,
and
then
we
can
make.
Then
we
have
an
index,
and
the
good
thing
here
is
that
fabric
keeps
this.
A
This
index
always
wrong,
so
this
index
will
be
updated
after
every
transaction.
So
and
we
don't
take,
we
don't
have
to
take
care.
Is
this
index
actual
or
not?
So
this
is
part
of
the
very
life
cycle,
so
we
will
always
have
a
warm
index
and
then
we
have
a
fast
and
performant
system
so
but
be
careful
with
indexing.
So
if
you
have
too
much
indexes,
then
it
can
be
too
much.
B
B
B
B
B
B
B
A
A
Options
do
the
same,
so
we
have
one
other
here
for
our
testing
and
I've
here
mapped
my
all
files
to
this
local
folders
here
so
sample
config.
It's
the
membership
service
provider.
Artifacts
is
the
folder
by
the
genesis,
blocks,
live
and
the
channel
transaction
and
lecture
data.
This
is
the
place
where
the
blockchain
stores
all
the
data
for.
B
A
And
here
we
have
our
couchdb
service
and
we
have
seen
we
have
defined
here,
the
couch
to
be
a
service,
for
it
is
being
serious
for
this
piano
and
then
we
have
a
culture,
big
user
and
the
code
should
be
a
password
see
this
id
default
converts.
So
don't
do
this
so
in
in
a
real
scenario
here:
use
environment
variables
or
something
like.
A
So
then,
the
port
here
this
is
the
standard
part
here
and
then
the
network
def
network
is
the
name
of
our
network,
and
then
we
have
to
link
this.
So
I
have
marked
this
here.
So
the
only
thing
what
we
have
to
do
is
we
have
to
put
here
in
this
foot
these
four
environment
variables
so
which
state
database
we
use.
So
we
use
culturally
and
then
the
service
name
here
in
the
port.
B
B
A
B
B
A
A
A
Run
it
in
the
file
in
the
foreground,
so
we
don't
have
access
to
the
terminal
here
to
see
all
the
log
messages
in
the
second
terminal
here.
This
is
the
place
where
the
chain
code
is
started
and
stopped,
and
so
on
so
that
we
can
modify
our
chain
code
and
here
in
the
in
the
third
container,
we
will
use.
B
B
A
B
A
B
A
B
B
A
B
A
A
A
Yeah
and
the
main
file
must
be
here,
called
the
index
chairs
file
and
very
important
here,
the
start
command
and
that's
the
reas.
That's
that's
really
important
that
you
put
in
this
start
property
here
with
this
value
and
this
fabric
chain
code.
Node
is
a
program
which
comes
with
the
fabric
scheme.
So
that's
the
reason
why
we
have
to
use
the
we
have
to
use
this
npm
package,
favorite
skim.
When
you
install
this,
then
you
will
have
also
this
favorite.
A
B
A
A
And
then
we
have
two
special
methods
here,
and
this
is
before
transaction
and
after
transaction
and
in
the
default
transaction.
This
function
is
called
like
it,
like
the
name
says
before
the
transaction
happened.
So
this
is
good
for
logging.
If
you
need
the
transaction
id
for
this
particular
request
or
something
whatever
for
checking
for
whatever
you
do
so,
and
this
is
also
optional.
A
So
when
you
don't
call
this,
then
it
doesn't
matter,
but
you
can
use
it
and
then
this
is
called
before
the
transaction
happened,
and
the
second
is
after
transaction
here
with
the
last
one,
and
that's
the
same
so
and
you
can
also
when
this
is
called,
then
you
can
trigger
an
event
or
a
log
message
or
whatever
you
want
so,
but
this
is
done
after
the
transaction
is
ready
and
then
we
have
implemented
two
functions
in
the
last
session.
This
store.
A
So
and
these
both
companies
have
decided
to
change
this
rules
and
then
they
say:
okay,
we,
I
need
more
revenue
percentage
from
you,
and
then
we
have
to
change
this
here
and
then
we
have
to
change
this
here
and
then
we
have
to
see
how
we
can
upgrade
this
existing
chain
code
in
a
running
network
with
another
version
of
this
chain
code.
So
that's
the
reason
why
I
have
put
here
so
simple
numbers.
A
Then
we
can
in
a
later
session
we
can
see
when
the
system
is
running
and
then
the
two
parties
say:
okay.
Now
we
have
to
change
this
business
rules,
then
how
we
can
change
this
in
the
chain
code.
So
that's
the
reason
why
we
have
this
here
in
place
and
here's
our
model.
What
we
have
seen
here
is
how
we
have
created
the
composite
key
with
the
layout
here
year
month
and
text
and.
A
A
Or
we
update
an
existing
asset,
but
in
this
scenario
we
only
create
an
asset.
We
never
update
the
state
of
an
asset
here
and
important
here
is
that
we
we
can.
We
have
here
a
property,
so
this
is
the
ctx
the
context
and,
through
this
context,
parameter
we
have
access
to
this
stop
interface
and
the
stop
interface
provide
us
different
methods,
and
one
of
them
is
the
bootstrap
and
yeah.
This
is
the
line
where
the
the.
A
Yeah
and
the
value
is
stored
into
the
blockchain,
and
here
you
can
see
that
this
is
the
key,
so
this
key
could
be
a
number
a
string
whatever.
I
am
something
like
a
composite
key.
There
is
another
method
which
creates
this
composite
key
here.
Also
provided
with
this
from
the
stop
interface
here
and
then
here
we
have
the
value
and
the
value
is
nothing
more
than
a
buffer
applied
a
party
way
and
we
can
stringify
this
yeah.
So
we
can,
we
have
here.
A
And
the
main
function
here,
the
important
part
is
this:
git
state
partition
composite
key,
and
we
have
here
the
key.
The
layout
of
the
key
and
the
keys
itself
are
in
a
way,
and
the
array
must
be
in
this
in
this
order
and
then
when
we
have
only
the
year,
then
it
creates
only
the
year
when
we
have
here
and
month.
Then
it
creates
year
and
month
and
when
we
have
also
the
transaction
id,
then
we
will
have
the
particular
transaction,
and
this
is
the
variability
which
we
have
with
the
before
our
queries
here.
A
And
then,
here
this
is
the
new
function
and
this
function
we
have
to
implement
so
okay,
but
now
we
have
this
function
a
little
bit
in
place,
and
then
we
have
to
finish
our
setup
and
to
finish
our
setup.
First,
we
have
to
install
the
chain
code
here
and
the
installation
of
the
chain
code
is
a
two-step
process.
So
the
first
step
is
that
we
have
to
package
the
chain
code
here
with
the
spear
life
cycle
chain
code
package
command,
and
then
we
can
install
it
with
be
a
life
cycle.
A
B
A
A
B
B
A
A
A
B
A
Installed
approved
and
committed,
and
now
this
this
time
we
are
ready
to
test
and
develop
our
chain
code
and
okay,
the
chain
code
should
run
now,
and
the
first
is
that
we
need
some
data
into
the
chain
code.
So
the
first
thing
is
that
we
set
store
some
data.
We
can
do
this
with
this.
With
this
cli
command,
be
a
chain
code
invoke.
So
that's
important
a
little
bit
when
you
try
to
reproduce
this
example.
A
So
please
notice
that
peer
chain
code
invoke
is
used
for
the
store
for
storing
yeah,
for
changing
for
for
creating
update
the
the
ledger
and
peer
train
code.
Query
is
used
only
for
queried
data
so,
and
that
makes
a
huge
difference,
because
the
invoked
process
goes
over
the
order
system
and
to
be
a
chain
code.
Query
queries
only
the
beer
which
you
are
connected
for
the
moment.
So
on
the
cli,
you
are
connected
to
the
environment
variables
and
from
the
nodejs
client.
A
You
are
connected
from
the
connection
profile,
which
you
have
used
to
connect
to
the
favorite
network,
so
but
notice.
Here
we
have
an
invoke
command
for
everything
which
changes
the
state
and
we
have
a
query
command
which
only
queries
the
state
of
an
asset
and
that's
pretty
cool.
I
think
because
when
we
have
in
our
scenario,
the
seller
could
have
a
single
node
in
his
own
data
center
and
he
has
only
the
rights
to
query
this
data
and
he
don't
has
to
be
accessed
to
our
blockchain
system.
B
A
Okay,
so
that
is
what
we
have
done
in
the
last
session,
and
now
we
want
to
create
another
query
in
this
one,
so
yeah,
and
for
this
one
we
need
here
so
the
first
in
this
command.
Here
the
command
is
an
and
json
array
and
the
first
one
is
called
arc
and
this
this
this
args
argument
here
has
an
array,
and
the
first
element
in
this
array
is
always
the
function
so,
and
this
is
the
function
which
we
recalled
and
then
the
next
parameter
here
the
next
elements
in
this
array.
A
A
A
A
A
A
B
A
This
is
the
new
function,
get
commission
statement
by
time
range,
and
here
we
don't.
We
only
have
one
parameter
one
option,
and
this
is
the
ctx
this
context,
which
will,
which
is
comes
through
there
for
through
the
system,
and
then
we
will
have
a
for
the
stack
interface.
We
have
the
possibility
to
get
all
the
arguments
which
we
have.
A
A
And
yeah
and
that's
the
query
we
are
going
to
send-
and
this
is
done
also
with
this
command
here
so
get
query.
Result
is
also
provided
through
this
stop
api,
and
so
I
think
most
functions
are
provided
through
this
ctx
stub
here,
and
it's
also
good
to
look
into
the
documentation
which
functions
you
can
query
which
you
can
use
here
and
that's
the
reason
why
I've
put
you
the
link
to
to
the
documentation
and
the
result
of
this
get
query.
Reside
is
an
iterator,
so
that's
important
here.
So
the
well.
A
B
A
And
the
last,
the
last
we
sight
the
last
line
is
represented
through
this
done
property
here,
and
until
this
is
available,
we
will
loop
through
this
while
loop
and
then
the
only
thing
is.
What
we
have
to
do
here
is
to
convert
this
back
as
a
as
a
string
in
the
udf8
format
from
the
puffer,
and
then
we
can
compose
an
output.
A
A
A
B
B
B
B
A
And-
and
here
we
have
now-
we
have
three
different
possibilities
to
query
our
data,
so
we
have
this
traditional
version
with
the
composite
key,
which
is
also
a
good
choice.
When
your
system
doesn't
need
the
query
like
this
one
or
you
can
use
this
couch
to
be
version,
and
then
you
can
use
all
the
capacities
that
couchdb
has
and
then
you
can
query
a
lot
more
and
one
example
of
this
is
this
one
here
and
yeah?
So
I
think
this
is
a.
A
B
A
A
A
A
B
B
B
B
A
This
network
script-
and
this
is
when
you
compare
it
with
the
1.4
version-
the
pgfs
network
example,
and
with
this
version,
then
this
is
really
really
a
game
changer.
I
think
so
only
especially
for
learning,
because
we
can
with
this
script
we
can
start
any
configuration,
so
we
can
start
a
configuration
with
the
level
db.
A
One,
for
example,
which
interacts
with
the
network.
You
have
also
to
create
the
pdf,
the
orders
and
for
every
network
element
in
this,
the
spheric
network.
You
have
to
create
an
identity,
and
here
in
this
network
script
you
find
sub
scripts,
where
you
can
see
how
you
can
do
this
later.
In
this
session,
I
have
planned
to
show
you
how
we
can
do
this
and
how
we
can
play
with
the
favorite
series,
because
fabric
say
is
also
important
here.
A
Maybe
we
will
do
it
earlier,
because
in
the
check,
the
chain
code
has
also
the
possibility
to
check
the
identity,
and
in
this
identities
we
can
have
some
special
properties.
So
maybe
this
is
called
an
attribute-based
chain
code
and
in
in
a
network-based
chain
code
that
we
can
say,
okay
in
this
set
in
this
certificate
from
this
user.
A
This
is
this.
Certificate
belongs
to
the
marketing
department
or
to
the
finance
department,
for
example,
and
the
only
members
of
this
finance
department
can
call
this
chain
code
function,
especially
this
revenue
function,
and
that's
the
reason
why
it's
important
also
to
know
as
a
chain
code
developer,
how
you
can
start
and
how
you
can
modify
this
certified
identities.
These
identities
and
yeah,
so
I
think
we-
this
is
a
good.
A
It's
also
good
for
note
for
for
learning
the
chain
code,
part
because
attribute-based
chain
code
and
is
an
topic
also
also
in
for
the
certification,
and
this
is
the
permission
system.
So
we
have
to
take
care
on
the
permissions
and
we
don't
have
a
username
and
a
password
here
to
give
a
particular
user
any
access
right,
because
we
have
an
rsa
out,
then
tr,
authentication
and
but
we
can
use.
A
A
A
B
B
A
B
A
A
I
have
shown
you
how
you
can
install
this
this
chain
code
also
on
the
test
on
the
official
test
network,
and
then
you
can
try
to
connect
to
when
you
try
to
connect
to
this
network.
You
have
to
set
the
proper
environment
variables,
so
we
have
seen
the
script
set
globals
with
one
two
and
three,
and
with
this
you
set
the
proper
environment
variable
so
that
the
local
beer
command
knows
to
which
peer?