<s>
Diazo	B-Application
,	O
previously	O
named	O
xdv	O
,	O
is	O
a	O
general-purpose	O
,	O
open	B-Application
source	I-Application
website	O
theming	O
tool	O
.	O
</s>
<s>
It	O
is	O
written	O
in	O
Python	B-Language
and	O
generates	O
XSLT	B-Application
.	O
</s>
<s>
Diazo	B-Application
creates	O
a	O
separation	O
between	O
theme	O
pages	O
(	O
static	O
HTML	O
)	O
and	O
transformation	O
rules	O
(	O
Diazo	B-Application
's	O
own	O
domain	B-Language
specific	I-Language
language	I-Language
based	O
in	O
XML	B-Protocol
)	O
,	O
allowing	O
web	O
designers	O
to	O
work	O
on	O
templates	O
in	O
plain	O
HTML	O
,	O
without	O
knowledge	O
of	O
XSLT	B-Application
or	O
special	O
template-related	O
codes	O
.	O
</s>
<s>
Diazo	B-Application
creates	O
a	O
themed	O
site	O
by	O
using	O
user-defined	O
rules	O
to	O
combine	O
vanilla	B-General_Concept
content	O
from	O
a	O
dynamic	O
website	O
together	O
with	O
a	O
static	O
HTML	O
theme	O
.	O
</s>
<s>
The	O
rules	O
file	O
(	O
conventionally	O
named	O
rules.xml	O
)	O
has	O
directives	O
which	O
,	O
for	O
example	O
,	O
may	O
replace	O
the	O
contents	O
of	O
an	O
HTML	O
node	O
in	O
the	O
theme	O
with	O
the	O
contents	O
of	O
one	O
in	O
the	O
content	O
.	O
</s>
<s>
The	O
Diazo	B-Application
compiler	O
generates	O
XSLT	B-Application
,	O
which	O
can	O
be	O
deployed	O
on	O
any	O
proxying	O
web	O
server	O
with	O
an	O
XSLT	B-Application
processor	I-Application
such	O
as	O
Apache	B-Application
(	O
using	O
mod_transform	O
)	O
,	O
Varnish	B-Language
,	O
or	O
WSGI	B-Language
.	O
</s>
<s>
WSGI	B-Language
also	O
has	O
more	O
direct	O
Diazo	B-Application
support	O
:	O
the	O
DiazoMiddleware	O
filter	O
will	O
compile	O
and	O
cache	O
Diazo	B-Application
themes	O
on	O
the	O
fly	O
.	O
</s>
<s>
Nginx	O
has	O
an	O
XSLT	B-Application
processor	I-Application
,	O
but	O
,	O
as	O
of	O
March	O
2012	O
,	O
it	O
requires	O
the	O
unthemed	O
website	O
(	O
the	O
content	O
)	O
to	O
use	O
strict	O
XHTML	O
.	O
</s>
<s>
Diazo	B-Application
was	O
originally	O
a	O
reimplementation	O
of	O
an	O
earlier	O
software	O
called	O
Deliverance	O
.	O
</s>
<s>
Where	O
Deliverance	O
would	O
handle	O
the	O
HTML	O
transformation	O
in	O
Python	B-Language
,	O
Diazo	B-Application
generates	O
XSLT	B-Application
which	O
can	O
then	O
be	O
used	O
to	O
defer	O
the	O
actual	O
transformation	O
to	O
faster	O
XSLT	B-Application
engines	O
.	O
</s>
<s>
The	O
name	O
change	O
to	O
Diazo	B-Application
(	O
from	O
xdv	O
)	O
was	O
announced	O
at	O
the	O
Plone	B-Language
conference	O
2010	O
.	O
</s>
<s>
A	O
major	O
motivation	O
for	O
the	O
name	O
change	O
was	O
to	O
reduce	O
ambiguity	O
,	O
as	O
the	O
XDV	O
name	O
was	O
used	O
by	O
both	O
collective.xdv	O
(	O
a	O
Plone-specific	O
theming	O
package	O
,	O
now	O
called	O
plone.app.theming	O
)	O
and	O
by	O
the	O
stand-alone	O
XDV	O
tools	O
(	O
now	O
called	O
Diazo	B-Application
)	O
.	O
</s>
<s>
Diazo	B-Application
is	O
based	O
on	O
DVNG	B-Application
,	O
a	O
prototype	O
version	O
of	O
xdv	O
.	O
</s>
<s>
Diazo	B-Application
originally	O
implemented	O
only	O
a	O
subset	O
of	O
the	O
features	O
in	O
Deliverance	O
,	O
but	O
now	O
has	O
similar	O
features	O
,	O
although	O
their	O
configuration	O
language	O
is	O
not	O
completely	O
compatible	O
.	O
</s>
<s>
Diazo	B-Application
has	O
become	O
the	O
de	O
facto	O
standard	O
for	O
theming	O
in	O
Plone	B-Language
4	O
and	O
is	O
included	O
in	O
Plone	B-Language
4.2	O
and	O
later	O
.	O
</s>
<s>
The	O
basic	O
directives	O
of	O
Diazo	B-Application
include	O
:	O
replace	O
(	O
replace	O
a	O
node	O
or	O
attribute	O
in	O
the	O
theme	O
with	O
that	O
from	O
content	O
)	O
,	O
before	O
and	O
after	O
(	O
insert	O
a	O
node	O
before	O
or	O
after	O
another	O
)	O
,	O
drop	O
(	O
delete	O
a	O
node	O
or	O
attribute	O
)	O
,	O
strip	O
(	O
remove	O
a	O
tag	O
but	O
not	O
its	O
child	O
nodes	O
)	O
,	O
merge	O
,	O
and	O
copy	O
.	O
</s>
