<s>
Yet	O
Another	O
Next	O
Generation	O
(	O
YANG	B-Application
,	O
/jæŋ/	O
,	O
which	O
rhymes	O
with	O
"	O
hang	O
"	O
)	O
is	O
a	O
data	B-Language
modeling	I-Language
language	I-Language
for	O
the	O
definition	O
of	O
data	O
sent	O
over	O
network	O
management	O
protocols	O
such	O
as	O
the	O
NETCONF	B-Protocol
and	O
RESTCONF	O
.	O
</s>
<s>
The	O
YANG	B-Application
data	B-Language
modeling	I-Language
language	I-Language
is	O
maintained	O
by	O
the	O
NETMOD	O
working	O
group	O
in	O
the	O
Internet	O
Engineering	O
Task	O
Force	O
(	O
IETF	O
)	O
and	O
initially	O
was	O
published	O
as	O
in	O
October	O
2010	O
,	O
with	O
an	O
update	O
in	O
August	O
2016	O
(	O
)	O
.	O
</s>
<s>
The	O
data	B-Language
modeling	I-Language
language	I-Language
can	O
be	O
used	O
to	O
model	O
both	O
configuration	O
data	O
as	O
well	O
as	O
state	O
data	O
of	O
network	O
elements	O
.	O
</s>
<s>
Furthermore	O
,	O
YANG	B-Application
can	O
be	O
used	O
to	O
define	O
the	O
format	O
of	O
event	O
notifications	O
emitted	O
by	O
network	O
elements	O
and	O
it	O
allows	O
data	O
modelers	O
to	O
define	O
the	O
signature	O
of	O
remote	B-Operating_System
procedure	I-Operating_System
calls	I-Operating_System
that	O
can	O
be	O
invoked	O
on	O
network	O
elements	O
via	O
the	O
NETCONF	B-Protocol
protocol	O
.	O
</s>
<s>
XML	B-Protocol
or	O
JSON	B-General_Concept
,	O
that	O
the	O
network	B-Protocol
configuration	I-Protocol
protocol	I-Protocol
supports	O
.	O
</s>
<s>
YANG	B-Application
is	O
a	O
modular	O
language	O
representing	O
data	O
structures	O
in	O
an	O
XML	B-Protocol
tree	O
format	O
.	O
</s>
<s>
The	O
data	B-Language
modeling	I-Language
language	I-Language
comes	O
with	O
a	O
number	O
of	O
built-in	O
data	O
types	O
.	O
</s>
<s>
YANG	B-Application
data	O
models	O
can	O
use	O
XPATH	B-Language
expressions	O
to	O
define	O
constraints	O
on	O
the	O
elements	O
of	O
a	O
YANG	B-Application
data	O
model	O
.	O
</s>
<s>
Many	O
network	O
management	O
protocols	O
have	O
associated	O
data	B-Language
modeling	I-Language
languages	I-Language
.	O
</s>
<s>
The	O
first	O
widely	O
deployed	O
Internet	O
standard	O
for	O
network	O
management	O
was	O
the	O
Simple	B-Protocol
Network	I-Protocol
Management	I-Protocol
Protocol	I-Protocol
(	O
SNMP	B-Protocol
)	O
.	O
</s>
<s>
The	O
data	B-Language
modeling	I-Language
language	I-Language
associated	O
with	O
SNMP	B-Protocol
was	O
called	O
the	O
Structure	B-Application
of	I-Application
Management	I-Application
Information	I-Application
(	O
SMI	O
)	O
.	O
</s>
<s>
The	O
SMI	O
language	O
itself	O
was	O
based	O
on	O
the	O
1988	O
version	O
of	O
the	O
Abstract	B-Protocol
Syntax	I-Protocol
Notation	I-Protocol
One	I-Protocol
(	O
ASN.1	B-Protocol
)	O
.	O
</s>
<s>
The	O
current	O
version	O
of	O
the	O
SMI	O
language	O
,	O
SMIv2	O
defined	O
in	O
,	O
has	O
developed	O
into	O
an	O
extended	O
subset	O
of	O
ASN.1	B-Protocol
.	O
</s>
<s>
One	O
motivation	O
was	O
to	O
decouple	O
SMIng	O
from	O
the	O
management	O
protocol	O
SNMP	B-Protocol
and	O
to	O
give	O
SMIng	O
a	O
syntactic	O
structure	O
that	O
is	O
both	O
easy	O
to	O
parse	O
for	O
computer	O
programs	O
and	O
easy	O
to	O
learn	O
for	O
people	O
familiar	O
with	O
programming	O
languages	O
that	O
use	O
a	O
C-like	O
notation	O
.	O
</s>
<s>
Soon	O
after	O
the	O
development	O
of	O
the	O
NETCONF	B-Protocol
protocol	O
in	O
the	O
IETF	O
,	O
it	O
became	O
clear	O
that	O
a	O
data	B-Language
modeling	I-Language
language	I-Language
was	O
needed	O
to	O
define	O
data	O
models	O
manipulated	O
by	O
the	O
NETCONF	B-Protocol
protocol	O
.	O
</s>
<s>
A	O
design	O
team	O
created	O
a	O
proposal	O
that	O
became	O
the	O
basis	O
of	O
the	O
YANG	B-Application
language	O
.	O
</s>
<s>
However	O
,	O
based	O
on	O
the	O
lessons	O
learned	O
from	O
the	O
SMIng	O
project	O
,	O
no	O
attempts	O
were	O
made	O
to	O
make	O
the	O
YANG	B-Application
protocol	O
neutral	O
.	O
</s>
<s>
Instead	O
,	O
YANG	B-Application
ties	O
into	O
concepts	O
of	O
the	O
NETCONF	B-Protocol
protocol	O
,	O
such	O
as	O
the	O
assumption	O
that	O
data	O
model	O
instances	O
can	O
be	O
serialized	O
into	O
XML	B-Protocol
.	O
</s>
<s>
Standardization	O
of	O
YANG	B-Application
started	O
with	O
the	O
formation	O
of	O
the	O
NETMOD	O
working	O
group	O
in	O
April	O
2008	O
.	O
</s>
<s>
The	O
YANG	B-Application
1.0	O
specification	O
was	O
published	O
as	O
in	O
October	O
2010	O
.	O
</s>
<s>
Recently	O
,	O
the	O
NETMOD	O
working	O
group	O
has	O
been	O
working	O
on	O
YANG	B-Application
1.1	O
,	O
which	O
has	O
been	O
published	O
in	O
August	O
2016	O
in	O
.	O
</s>
<s>
The	O
following	O
YANG	B-Application
module	O
example-sports	O
shows	O
a	O
data	O
model	O
for	O
team	O
sports	O
.	O
</s>
<s>
The	O
module	O
declares	O
a	O
namespace	O
and	O
a	O
prefix	O
and	O
imports	O
the	O
type	O
library	O
module	O
ietf-yang-types	O
before	O
defining	O
the	O
type	O
season	O
.	O
</s>
<s>
The	O
code	O
block	O
below	O
shows	O
the	O
JSON	B-General_Concept
representation	O
of	O
an	O
instantiation	O
of	O
the	O
example-sports	O
data	O
model	O
.	O
</s>
<s>
The	O
code	O
block	O
below	O
shows	O
the	O
XML	B-Protocol
representation	O
of	O
an	O
instantiation	O
of	O
the	O
example-sports	O
data	O
model	O
.	O
</s>
<s>
The	O
following	O
Request	O
for	O
Comments	O
(	O
RFCs	O
)	O
define	O
the	O
YANG	B-Application
language	O
and	O
some	O
basic	O
extensions	O
:	O
</s>
<s>
The	O
following	O
requests	O
for	O
comments	O
define	O
standards-track	O
protocols	O
that	O
are	O
(	O
partially	O
)	O
defined	O
using	O
YANG	B-Application
modules	O
:	O
</s>
<s>
The	O
following	O
RFCs	O
define	O
standards-track	O
YANG	B-Application
data	O
models	O
:	O
</s>
<s>
The	O
following	O
requests	O
for	O
comments	O
are	O
experimental	O
specifications	O
that	O
use	O
or	O
extend	O
YANG	B-Application
:	O
</s>
<s>
is	O
a	O
YANG-based	O
toolchain	O
including	O
interactive	O
CLI	O
,	O
NETCONF	B-Protocol
and	O
RESTCONF	O
interfaces	O
written	O
in	O
C	O
.	O
</s>
<s>
is	O
a	O
YANG-based	O
configuration	O
and	O
operational	O
datastore	O
for	O
Unix/Linux	O
applications	O
.	O
</s>
<s>
is	O
a	O
Python	O
3	O
library	O
for	O
working	O
with	O
JSON	B-General_Concept
encoded	O
configuration	O
and	O
state	O
data	O
modeled	O
using	O
the	O
YANG	B-Application
data	B-Language
modeling	I-Language
language	I-Language
.	O
</s>
<s>
is	O
a	O
YANG-to-API	O
compiler	O
generating	O
APIs	O
in	O
multiple	O
languages	O
(	O
e.g.	O
</s>
