<s>
XML-RPC	B-Protocol
is	O
a	O
remote	B-Operating_System
procedure	I-Operating_System
call	I-Operating_System
(	O
RPC	O
)	O
protocol	O
which	O
uses	O
XML	B-Protocol
to	O
encode	O
its	O
calls	O
and	O
HTTP	B-Protocol
as	O
a	O
transport	O
mechanism	O
.	O
</s>
<s>
The	O
XML-RPC	B-Protocol
protocol	O
was	O
created	O
in	O
1998	O
by	O
Dave	O
Winer	O
of	O
UserLand	O
Software	O
and	O
Microsoft	O
,	O
with	O
Microsoft	O
seeing	O
the	O
protocol	O
as	O
an	O
essential	O
part	O
of	O
scaling	O
up	O
its	O
efforts	O
in	O
business-to-business	O
e-commerce	O
.	O
</s>
<s>
As	O
new	O
functionality	O
was	O
introduced	O
,	O
the	O
standard	O
evolved	O
into	O
what	O
is	O
now	O
SOAP	B-Protocol
.	O
</s>
<s>
UserLand	O
supported	O
XML-RPC	B-Protocol
from	O
version	O
5.1	O
of	O
its	O
Frontier	O
web	O
content	O
management	O
system	O
,	O
released	O
in	O
June	O
1998	O
.	O
</s>
<s>
XML-RPC	B-Protocol
'	O
s	O
idea	O
of	O
a	O
human-readable-and-writable	O
,	O
script-parsable	O
standard	O
for	O
HTTP-based	O
requests	O
and	O
responses	O
has	O
also	O
been	O
implemented	O
in	O
competing	O
specifications	O
such	O
as	O
Allaire	O
's	O
Web	B-Protocol
Distributed	I-Protocol
Data	I-Protocol
Exchange	I-Protocol
(	O
WDDX	B-Protocol
)	O
and	O
webMethod	O
's	O
Web	O
Interface	O
Definition	O
Language	O
(	O
WIDL	O
)	O
.	O
</s>
<s>
Prior	O
art	O
wrapping	O
COM	B-Application
,	O
CORBA	B-Architecture
,	O
and	O
Java	B-Language
RMI	I-Language
objects	O
in	O
XML	B-Protocol
syntax	O
and	O
transporting	O
them	O
via	O
HTTP	B-Protocol
also	O
existed	O
in	O
DataChannel	O
's	O
WebBroker	O
technology	O
.	O
</s>
<s>
The	O
generic	O
use	O
of	O
XML	B-Protocol
for	O
remote	B-Operating_System
procedure	I-Operating_System
call	I-Operating_System
(	O
RPC	O
)	O
was	O
patented	O
by	O
Phillip	O
Merrick	O
,	O
Stewart	O
Allen	O
,	O
and	O
Joseph	O
Lapp	O
in	O
April	O
2006	O
,	O
claiming	O
benefit	O
to	O
a	O
provisional	O
application	O
filed	O
in	O
March	O
1998	O
.	O
</s>
<s>
In	O
XML-RPC	B-Protocol
,	O
a	O
client	O
performs	O
an	O
RPC	O
by	O
sending	O
an	O
HTTP	B-Protocol
request	O
to	O
a	O
server	O
that	O
implements	O
XML-RPC	B-Protocol
and	O
receives	O
the	O
HTTP	B-Protocol
response	O
.	O
</s>
<s>
For	O
example	O
,	O
you	O
can	O
have	O
a	O
parameter	O
that	O
is	O
an	O
array	B-Data_Structure
of	O
five	O
integers	O
.	O
</s>
<s>
Identification	O
of	O
clients	O
for	O
authorization	O
purposes	O
can	O
be	O
achieved	O
using	O
popular	O
HTTP	B-Protocol
security	O
methods	O
.	O
</s>
<s>
Basic	B-Protocol
access	I-Protocol
authentication	I-Protocol
can	O
be	O
used	O
for	O
identification	O
and	O
authentication	O
.	O
</s>
<s>
In	O
comparison	O
to	O
RESTful	O
protocols	O
,	O
where	O
resource	O
representations	O
(	O
documents	O
)	O
are	O
transferred	O
,	O
XML-RPC	B-Protocol
is	O
designed	O
to	O
call	O
methods	O
.	O
</s>
<s>
The	O
practical	O
difference	O
is	O
just	O
that	O
XML-RPC	B-Protocol
is	O
much	O
more	O
structured	O
,	O
which	O
means	O
common	O
library	O
code	O
can	O
be	O
used	O
to	O
implement	O
clients	O
and	O
servers	O
and	O
there	O
is	O
less	O
design	O
and	O
documentation	O
work	O
for	O
a	O
specific	O
application	O
protocol	O
.	O
</s>
<s>
One	O
salient	O
technical	O
difference	O
between	O
typical	O
RESTful	O
protocols	O
and	O
XML-RPC	B-Protocol
is	O
that	O
many	O
RESTful	O
protocols	O
use	O
the	O
HTTP	B-Protocol
URI	O
for	O
parameter	O
information	O
,	O
whereas	O
with	O
XML-RPC	B-Protocol
,	O
the	O
URI	O
just	O
identifies	O
the	O
server	O
.	O
</s>
<s>
JSON-RPC	B-General_Concept
is	O
similar	O
to	O
XML-RPC	B-Protocol
.	O
</s>
<s>
Common	O
datatypes	O
are	O
converted	O
into	O
their	O
XML	B-Protocol
equivalents	O
with	O
example	O
values	O
shown	O
below	O
:	O
</s>
<s>
An	O
example	O
of	O
a	O
typical	O
XML-RPC	B-Protocol
request	O
would	O
be	O
:	O
</s>
<s>
An	O
example	O
of	O
a	O
typical	O
XML-RPC	B-Protocol
response	O
would	O
be	O
:	O
</s>
<s>
A	O
typical	O
XML-RPC	B-Protocol
fault	O
would	O
be	O
:	O
</s>
<s>
Recent	O
critics	O
(	O
from	O
2010	O
and	O
onwards	O
)	O
of	O
XML-RPC	B-Protocol
argue	O
that	O
RPC	O
calls	O
can	O
be	O
made	O
with	O
plain	O
XML	B-Protocol
,	O
and	O
that	O
XML-RPC	B-Protocol
does	O
not	O
add	O
any	O
value	O
over	O
XML	B-Protocol
.	O
</s>
<s>
Both	O
XML-RPC	B-Protocol
and	O
XML	B-Protocol
require	O
an	O
application-level	O
data	O
model	O
,	O
such	O
as	O
which	O
field	O
names	O
are	O
defined	O
in	O
the	O
XML	B-Protocol
schema	O
or	O
the	O
parameter	O
names	O
in	O
XML-RPC	B-Protocol
.	O
</s>
<s>
Furthermore	O
,	O
XML-RPC	B-Protocol
uses	O
about	O
4	O
times	O
the	O
number	O
of	O
bytes	O
compared	O
to	O
plain	O
XML	B-Protocol
to	O
encode	O
the	O
same	O
objects	O
,	O
which	O
is	O
itself	O
verbose	O
compared	O
to	O
JSON	B-General_Concept
.	O
</s>
