<s>
Apache	B-Language
Velocity	I-Language
first	O
released	O
in	O
April	O
2001	O
,	O
is	O
a	O
Java-based	O
template	B-Application
engine	I-Application
that	O
provides	O
a	O
template	B-Application
language	I-Application
to	O
reference	O
objects	O
defined	O
in	O
Java	B-Language
code	I-Language
.	O
</s>
<s>
It	O
aims	O
to	O
ensure	O
clean	O
separation	O
between	O
the	O
presentation	O
tier	O
and	O
business	O
tiers	O
in	O
a	O
Web	B-Application
application	I-Application
(	O
the	O
model	O
–	O
view	O
–	O
controller	O
design	O
pattern	O
)	O
.	O
</s>
<s>
Velocity	O
is	O
an	O
open	B-Application
source	I-Application
software	I-Application
project	O
hosted	O
by	O
the	O
Apache	O
Software	O
Foundation	O
.	O
</s>
<s>
It	O
is	O
released	O
under	O
the	O
Apache	B-Application
License	I-Application
.	O
</s>
<s>
Jon	O
Scott	O
Stevens	O
derived	O
the	O
name	O
from	O
the	O
AltiVec	B-General_Concept
Velocity	B-General_Concept
Engine	I-General_Concept
in	O
the	O
PowerPC	B-General_Concept
G4	I-General_Concept
chip	O
.	O
</s>
<s>
Web	B-Application
applications	I-Application
:	O
Web	B-Operating_System
developers	I-Operating_System
render	O
HTML	B-Language
page	O
structures	O
.	O
</s>
<s>
Source	O
code	O
generation	O
:	O
Velocity	O
can	O
be	O
used	O
to	O
generate	O
Java	B-Language
,	O
SQL	B-Language
,	O
or	O
PostScript	B-Language
source	O
code	O
,	O
based	O
on	O
templates	B-Application
.	O
</s>
<s>
A	O
number	O
of	O
open	B-Application
source	I-Application
and	O
commercial	O
development	O
software	B-Application
packages	I-Application
use	O
Velocity	O
in	O
this	O
manner	O
.	O
</s>
<s>
Using	O
Velocity	O
,	O
the	O
email	O
template	B-Application
can	O
be	O
stored	O
in	O
a	O
text	B-General_Concept
file	I-General_Concept
,	O
rather	O
than	O
directly	O
embedded	O
in	O
Java	B-Language
code	I-Language
.	O
</s>
<s>
XML	B-Protocol
transformation	O
:	O
Velocity	O
provides	O
an	O
Ant	B-Application
task	O
,	O
called	O
Anakia	O
,	O
which	O
reads	O
an	O
XML	B-Protocol
file	O
and	O
makes	O
it	O
available	O
to	O
a	O
Velocity	O
template	B-Application
.	O
</s>
<s>
A	O
common	O
application	O
is	O
to	O
convert	O
software	O
documentation	O
stored	O
in	O
a	O
generic	O
"	O
xdoc	O
"	O
format	O
into	O
a	O
styled	O
HTML	B-Language
document	O
.	O
</s>
<s>
AWS	O
API	O
Gateway	O
uses	O
Apache	B-Language
Velocity	I-Language
engine	O
for	O
body	O
mapping	O
templates	B-Application
-	O
JSON	B-General_Concept
is	O
output	O
.	O
</s>
<s>
The	O
following	O
template	B-Application
:	O
</s>
<s>
processed	O
by	O
Velocity	O
produces	O
the	O
following	O
HTML	B-Language
:	O
</s>
<s>
Another	O
example	O
using	O
conditions:AWS	O
API	O
Gateway	O
body	O
mapping	O
template	B-Application
,	O
for	O
DynamoDB	B-Application
HTTP:Another	O
example	O
with	O
;	O
without	O
condition	O
will	O
fail	O
because	O
of	O
invalid	O
resulting	O
JSON:The	O
syntax	O
and	O
overall	O
concept	O
of	O
the	O
Apache	B-Language
Velocity	I-Language
templates	B-Application
is	O
similar	O
to	O
the	O
syntax	O
of	O
the	O
older	O
WebMacro	B-Language
template	B-Application
engine	I-Application
,	O
which	O
is	O
now	O
also	O
an	O
open	B-Application
source	I-Application
project	O
.	O
</s>
