<s>
Open	B-Protocol
Network	I-Protocol
Computing	I-Protocol
(	O
ONC	O
)	O
Remote	B-Operating_System
Procedure	I-Operating_System
Call	I-Operating_System
(	O
RPC	O
)	O
,	O
commonly	O
known	O
as	O
Sun	B-Protocol
RPC	I-Protocol
is	O
a	O
remote	B-Operating_System
procedure	I-Operating_System
call	I-Operating_System
system	O
.	O
</s>
<s>
ONC	O
was	O
originally	O
developed	O
by	O
Sun	O
Microsystems	O
in	O
the	O
1980s	O
as	O
part	O
of	O
their	O
Network	B-Protocol
File	I-Protocol
System	I-Protocol
project	O
.	O
</s>
<s>
ONC	O
is	O
based	O
on	O
calling	O
conventions	O
used	O
in	O
Unix	B-Application
and	O
the	O
C	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
It	O
serializes	B-Application
data	O
using	O
the	O
External	B-Protocol
Data	I-Protocol
Representation	I-Protocol
(	O
XDR	B-Protocol
)	O
,	O
which	O
has	O
also	O
found	O
some	O
use	O
to	O
encode	O
and	O
decode	O
data	O
in	O
files	O
that	O
are	O
to	O
be	O
accessed	O
on	O
more	O
than	O
one	O
platform	O
.	O
</s>
<s>
ONC	O
then	O
delivers	O
the	O
XDR	B-Protocol
payload	O
using	O
either	O
UDP	B-Protocol
or	O
TCP	B-Protocol
.	O
</s>
<s>
Access	O
to	O
RPC	O
services	O
on	O
a	O
machine	O
are	O
provided	O
via	O
a	O
port	B-Protocol
mapper	I-Protocol
that	O
listens	O
for	O
queries	O
on	O
a	O
well-known	O
port	O
(	O
number	O
111	O
)	O
over	O
UDP	B-Protocol
and	O
TCP	B-Protocol
.	O
</s>
<s>
ONC	B-Protocol
RPC	I-Protocol
was	O
described	O
in	O
RFC	O
1831	O
,	O
published	O
in	O
1995	O
.	O
</s>
<s>
Authentication	O
mechanisms	O
used	O
by	O
ONC	B-Protocol
RPC	I-Protocol
are	O
described	O
in	O
RFC	O
2695	O
,	O
RFC	O
2203	O
,	O
and	O
RFC	O
2623	O
.	O
</s>
<s>
Implementations	O
of	O
ONC	B-Protocol
RPC	I-Protocol
exist	O
in	O
most	O
Unix-like	B-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
Microsoft	O
supplies	O
an	O
implementation	O
for	O
Windows	B-Application
in	O
their	O
Microsoft	B-Application
Windows	I-Application
Services	O
for	O
UNIX	B-Application
product	O
;	O
in	O
addition	O
,	O
a	O
number	O
of	O
third-party	O
implementation	O
of	O
ONC	B-Protocol
RPC	I-Protocol
for	O
Windows	B-Application
exist	O
,	O
including	O
versions	O
for	O
C/C	O
++	O
,	O
Java	B-Language
,	O
and	O
.NET	O
(	O
see	O
external	O
links	O
)	O
.	O
</s>
<s>
In	O
2009	O
,	O
Sun	O
relicensed	O
the	O
ONC	B-Protocol
RPC	I-Protocol
code	O
under	O
the	O
standard	O
3-clause	O
BSD	B-Operating_System
license	I-Operating_System
and	O
then	O
reconfirmed	O
by	O
Oracle	B-Application
Corporation	I-Application
in	O
2010	O
following	O
confusion	O
about	O
the	O
scope	O
of	O
the	O
relicensing	O
.	O
</s>
<s>
Systems	O
such	O
as	O
DCE	B-Operating_System
,	O
CORBA	B-Architecture
and	O
SOAP	B-Protocol
are	O
generally	O
used	O
in	O
this	O
wider	O
role	O
.	O
</s>
