<s>
XCB	B-Language
(	O
X	B-Device
protocol	I-Device
C-language	O
Binding	O
)	O
is	O
a	O
library	B-Library
implementing	O
the	O
client-side	O
of	O
the	O
X11	B-Device
display	O
server	O
protocol	O
.	O
</s>
<s>
XCB	B-Language
is	O
written	O
in	O
the	O
C	B-Language
programming	I-Language
language	I-Language
and	O
distributed	O
under	O
the	B-License
MIT	I-License
License	I-License
.	O
</s>
<s>
The	O
project	O
was	O
started	O
in	O
2001	O
by	O
Bart	O
Massey	O
and	O
aims	O
to	O
replace	O
Xlib	B-Language
.	O
</s>
<s>
XCB	B-Language
was	O
designed	O
as	O
a	O
smaller	O
,	O
modernized	O
replacement	O
for	O
Xlib	B-Language
,	O
previously	O
the	O
primary	O
C	B-Language
library	B-Library
for	O
communicating	O
with	O
the	O
X	O
window	O
system	O
,	O
coinciding	O
with	O
a	O
more	O
complete	O
overhaul	O
of	O
the	O
X	O
implementation	O
that	O
took	O
place	O
during	O
the	O
early	O
2000s	O
.	O
</s>
<s>
The	O
main	O
goals	O
of	O
XCB	B-Language
are	O
to	O
:	O
</s>
<s>
The	O
required	O
size	O
reduction	O
is	O
achieved	O
primarily	O
by	O
restricting	O
XCB	B-Language
's	O
scope	O
to	O
handling	O
the	O
X	B-Device
protocol	I-Device
and	O
omitting	O
Xlib	B-Language
functionality	O
such	O
as	O
its	O
extensive	O
utility	O
library	B-Library
,	O
much	O
of	O
which	O
saw	O
little	O
use	O
by	O
applications	O
.	O
</s>
<s>
This	O
results	O
in	O
a	O
factor	O
thirty	O
reduction	O
of	O
the	O
compiled	O
library	B-Library
size	O
(	O
as	O
of	O
2004	O
)	O
.	O
</s>
<s>
Secondary	O
goals	O
include	O
making	O
the	O
C	B-Language
interface	O
asynchronous	O
,	O
facilitating	O
better	O
multithreading	B-Operating_System
and	O
making	O
it	O
easier	O
to	O
implement	O
extensions	O
(	O
via	O
XML	B-Protocol
protocol	O
descriptions	O
)	O
.	O
</s>
<s>
The	O
core	O
and	O
extension	O
protocol	O
descriptions	O
are	O
in	O
XML	B-Protocol
,	O
with	O
a	O
program	O
written	O
in	O
Python	B-Language
creating	O
the	O
C	B-Language
bindings	O
.	O
</s>
<s>
(	O
Previous	O
versions	O
used	O
XSLT	B-Application
and	O
M4	B-Device
.	O
)	O
</s>
<s>
Massey	O
and	O
others	O
have	O
worked	O
to	O
prove	O
key	O
portions	O
of	O
XCB	B-Language
formally	O
correct	O
using	O
Z	B-Language
notation	I-Language
.	O
</s>
<s>
(	O
Xlib	B-Language
has	O
long	O
been	O
known	O
to	O
contain	O
errors	O
.	O
)	O
</s>
<s>
Xlib/XCB	B-Language
provides	O
application	B-Operating_System
binary	I-Operating_System
interface	I-Operating_System
compatibility	O
with	O
both	O
Xlib	B-Language
and	O
XCB	B-Language
,	O
providing	O
an	O
incremental	O
porting	O
path	O
.	O
</s>
<s>
Xlib/XCB	B-Language
uses	O
the	O
protocol	O
layer	O
of	O
Xlib	B-Language
,	O
but	O
replaces	O
the	O
Xlib	B-Language
transport	O
layer	O
with	O
XCB	B-Language
,	O
and	O
provides	O
access	O
to	O
the	O
underlying	O
XCB	B-Language
connection	O
for	O
direct	O
use	O
of	O
XCB	B-Language
.	O
</s>
<s>
Xlib/XCB	B-Language
allows	O
an	O
application	O
to	O
open	O
a	O
single	O
connection	O
to	O
the	O
X	O
display	O
server	O
and	O
use	O
both	O
XCB	B-Language
and	O
Xlib	B-Language
,	O
possibly	O
through	O
a	O
mixture	O
of	O
libraries	O
designed	O
for	O
one	O
or	O
the	O
other	O
.	O
</s>
<s>
XCB	B-Language
has	O
a	O
comparable	O
,	O
but	O
slightly	O
lower-level	O
API	O
than	O
Xlib	B-Language
,	O
as	O
can	O
be	O
seen	O
with	O
this	O
example	O
.	O
</s>
<s>
Creators	O
of	O
XCB	B-Language
have	O
invented	O
a	O
specialized	O
interface	B-General_Concept
description	I-General_Concept
language	I-General_Concept
to	O
model	O
X11	B-Device
protocol	I-Device
in	O
language-neutral	O
way	O
and	O
facilitate	O
generation	O
of	O
bindings	O
to	O
other	O
programming	O
languages	O
.	O
</s>
<s>
libxcb	O
itself	O
is	O
implemented	O
as	O
a	O
code	O
generator	O
and	O
a	O
tiny	O
C	B-Language
stub	O
of	O
utility	O
functions	O
.	O
</s>
<s>
The	O
XCB	B-Language
logo	O
was	O
produced	O
by	O
Gearóid	O
Molloy	O
,	O
author	O
of	O
the	O
web	O
comic	O
Neko	O
the	O
Kitty	O
,	O
and	O
donated	O
to	O
the	O
project	O
.	O
</s>
<s>
-	O
Perl	O
module	O
implementing	O
bindings	O
to	O
XCB	B-Language
.	O
</s>
<s>
-	O
The	O
Python	B-Language
binding	O
to	O
the	O
X	O
Window	O
System	O
using	O
XCB	B-Language
.	O
</s>
<s>
As	O
of	O
June	O
2013	O
,	O
it	O
does	O
not	O
support	O
Python	B-Language
3	O
.	O
</s>
<s>
Provided	O
by	O
freedesktop.org	B-Application
.	O
</s>
<s>
-	O
Another	O
Python	B-Language
binding	O
which	O
supports	O
Python	B-Language
2	O
&	O
3	O
as	O
well	O
as	O
several	O
more	O
X	O
extensions	O
than	O
xpyb	O
.	O
</s>
