<s>
In	O
software	O
,	O
an	O
XML	B-Operating_System
pipeline	I-Operating_System
is	O
formed	O
when	O
XML	B-Protocol
(	O
Extensible	B-Protocol
Markup	I-Protocol
Language	I-Protocol
)	O
processes	O
,	O
especially	O
XML	B-Language
transformations	I-Language
and	O
XML	B-Language
validations	I-Language
,	O
are	O
connected	O
.	O
</s>
<s>
For	O
instance	O
,	O
given	O
two	O
transformations	O
T1	O
and	O
T2	O
,	O
the	O
two	O
can	O
be	O
connected	O
so	O
that	O
an	O
input	O
XML	B-Protocol
document	I-Protocol
is	O
transformed	O
by	O
T1	O
and	O
then	O
the	O
output	O
of	O
T1	O
is	O
fed	O
as	O
input	O
document	O
to	O
T2	O
.	O
</s>
<s>
Simple	O
pipelines	B-Operating_System
like	O
the	O
one	O
described	O
above	O
are	O
called	O
linear	O
;	O
a	O
single	O
input	O
document	O
always	O
goes	O
through	O
the	O
same	O
sequence	O
of	O
transformations	O
to	O
produce	O
a	O
single	O
output	O
document	O
.	O
</s>
<s>
Transform	O
-	O
execute	O
a	O
transform	O
on	O
the	O
input	O
file	O
using	O
a	O
specified	O
XSLT	B-Application
file	O
.	O
</s>
<s>
Non-linear	O
operations	O
on	O
pipelines	B-Operating_System
may	O
include	O
:	O
</s>
<s>
XML	B-Operating_System
pipeline	I-Operating_System
languages	O
are	O
used	O
to	O
define	O
pipelines	B-Operating_System
.	O
</s>
<s>
A	O
program	O
written	O
with	O
an	O
XML	B-Operating_System
pipeline	I-Operating_System
language	O
is	O
implemented	O
by	O
software	O
known	O
as	O
an	O
XML	B-Operating_System
pipeline	I-Operating_System
engine	O
,	O
which	O
creates	O
processes	O
,	O
connects	O
them	O
together	O
and	O
finally	O
executes	O
the	O
pipeline	B-Operating_System
.	O
</s>
<s>
Existing	O
XML	B-Operating_System
pipeline	I-Operating_System
languages	O
include	O
:	O
</s>
<s>
XProc	B-Language
:	I-Language
An	I-Language
XML	I-Language
Pipeline	I-Language
Language	I-Language
is	O
a	O
W3C	O
Recommendation	O
for	O
defining	O
linear	O
and	O
non-linear	O
XML	B-Operating_System
pipelines	I-Operating_System
.	O
</s>
<s>
W3C	O
XML	B-Operating_System
Pipeline	I-Operating_System
Definition	O
Language	O
is	O
specified	O
in	O
a	O
W3C	O
Note	O
.	O
</s>
<s>
W3C	O
XML	B-Operating_System
Pipeline	I-Operating_System
Language	O
(	O
XPL	O
)	O
Version	O
1.0	O
(	O
Draft	O
)	O
is	O
specified	O
in	O
a	O
W3C	O
Submission	O
and	O
a	O
component	O
of	O
Orbeon	O
Presentation	O
Server	O
OPS	O
(	O
now	O
called	O
Orbeon	O
Forms	O
)	O
.	O
</s>
<s>
XPL	O
allows	O
the	O
declaration	O
of	O
complex	O
pipelines	B-Operating_System
with	O
conditionals	O
,	O
loops	O
,	O
tees	O
,	O
aggregations	O
,	O
and	O
sub-pipelines	O
.	O
</s>
<s>
XProc	B-Language
is	O
roughly	O
a	O
superset	O
of	O
XPL	O
.	O
</s>
<s>
Cocoon	B-Language
sitemaps	O
allow	O
,	O
among	O
other	O
functionality	O
,	O
the	O
declaration	O
of	O
XML	B-Operating_System
pipelines	I-Operating_System
.	O
</s>
<s>
Cocoon	B-Language
sitemaps	O
are	O
one	O
of	O
the	O
earliest	O
implementations	O
of	O
the	O
concept	O
of	O
XML	B-Operating_System
pipeline	I-Operating_System
.	O
</s>
<s>
smallx	O
XML	B-Operating_System
Pipelines	I-Operating_System
are	O
used	O
by	O
the	O
smallx	O
project	O
.	O
</s>
<s>
ServingXML	O
defines	O
a	O
vocabulary	O
for	O
expressing	O
flat-XML	O
,	O
XML-flat	O
,	O
flat-flat	O
,	O
and	O
XML-XML	O
transformations	O
in	O
pipelines	B-Operating_System
.	O
</s>
<s>
Circuits	O
are	O
collections	O
of	O
paths	O
through	O
which	O
fragments	O
of	O
XML	B-Protocol
stream	O
(	O
usually	O
as	O
SAX	O
or	O
DOM	O
events	O
)	O
.	O
</s>
<s>
Stylus	B-Application
Studio	I-Application
XML	B-Operating_System
Pipeline	I-Operating_System
is	O
a	O
visual	O
grammar	O
which	O
defines	O
the	O
following	O
operations	O
:	O
Input	O
,	O
Output	O
,	O
XQuery	O
,	O
XSLT	B-Application
,	O
Validate	O
,	O
XSL-FO	O
to	O
PDF	O
,	O
Convert	O
To	O
XML	B-Protocol
,	O
Convert	O
From	O
XML	B-Protocol
,	O
Choose	O
,	O
Warning	O
,	O
Stop	O
.	O
</s>
<s>
Different	O
XML	B-Operating_System
Pipeline	I-Operating_System
implementations	O
support	O
different	O
granularity	O
of	O
flow	O
.	O
</s>
<s>
Until	O
May	O
2010	O
,	O
there	O
was	O
no	O
widely	O
used	O
standard	O
for	O
XML	B-Operating_System
pipeline	I-Operating_System
languages	O
.	O
</s>
<s>
However	O
,	O
with	O
the	O
introduction	O
of	O
the	O
W3C	O
XProc	B-Language
standard	O
as	O
a	O
W3C	O
Recommendation	O
as	O
of	O
May	O
2010	O
,	O
widespread	O
adoption	O
can	O
be	O
expected	O
.	O
</s>
<s>
1972	O
Douglas	O
McIlroy	O
of	O
Bell	O
Laboratories	O
adds	O
the	O
pipe	O
operator	O
to	O
the	O
UNIX	B-Application
command	O
shell	O
.	O
</s>
<s>
This	O
allowed	O
programs	O
such	O
as	O
the	O
UNIX	B-Application
awk	B-Application
and	O
sed	B-Application
to	O
be	O
specialized	O
yet	O
work	O
together	O
.	O
</s>
<s>
For	O
more	O
details	O
see	O
Pipeline	B-Operating_System
(	O
Unix	B-Application
)	O
.	O
</s>
<s>
1993	O
developed	O
a	O
C++	O
toolkit	O
for	O
SGML	B-Language
processing	O
.	O
</s>
<s>
1998	O
Stefano	O
Mazzocchi	O
releases	O
the	O
first	O
version	O
of	O
Apache	B-Language
Cocoon	I-Language
,	O
one	O
of	O
the	O
first	O
software	O
programs	O
to	O
use	O
XML	B-Operating_System
pipelines	I-Operating_System
.	O
</s>
<s>
While	O
neither	O
submission	O
directly	O
became	O
a	O
W3C	O
recommendation	O
,	O
they	O
were	O
considered	O
key	O
sources	O
of	O
inspiration	O
for	O
the	O
W3C	O
XML	B-Protocol
Processing	O
Working	O
Group	O
.	O
</s>
<s>
September	O
2005	O
W3C	O
XML	B-Protocol
Processing	O
Working	O
Group	O
started	O
.	O
</s>
<s>
The	O
task	O
of	O
this	O
working	O
group	O
was	O
to	O
create	O
a	O
specification	O
for	O
an	O
XML	B-Protocol
pipelining	O
language	O
.	O
</s>
