<s>
In	O
web	B-Application
applications	I-Application
,	O
a	O
rewrite	B-Protocol
engine	I-Protocol
is	O
a	O
software	O
component	O
that	O
performs	O
rewriting	O
on	O
URLs	O
(	O
Uniform	O
Resource	O
Locators	O
)	O
,	O
modifying	O
their	O
appearance	O
.	O
</s>
<s>
This	O
modification	O
is	O
called	O
URL	B-Protocol
rewriting	I-Protocol
.	O
</s>
<s>
It	O
is	O
a	O
way	O
of	O
implementing	O
URL	O
mapping	O
or	O
routing	O
within	O
a	O
web	B-Application
application	I-Application
.	O
</s>
<s>
The	O
engine	O
is	O
typically	O
a	O
component	O
of	O
a	O
web	B-Application
server	I-Application
or	O
web	B-Application
application	I-Application
framework	I-Application
.	O
</s>
<s>
Rewritten	O
URLs	O
(	O
sometimes	O
known	O
as	O
short	O
,	O
pretty	O
or	O
fancy	O
URLs	O
,	O
search	B-Application
engine	I-Application
friendly	O
-	O
SEF	O
URLs	O
,	O
or	O
slugs	O
)	O
are	O
used	O
to	O
provide	O
shorter	O
and	O
more	O
relevant-looking	O
links	O
to	O
web	O
pages	O
.	O
</s>
<s>
The	O
technique	O
adds	O
a	O
layer	O
of	O
abstraction	B-Application
between	O
the	O
files	O
used	O
to	O
generate	O
a	O
web	O
page	O
and	O
the	O
URL	O
that	O
is	O
presented	O
to	O
the	O
outside	O
world	O
.	O
</s>
<s>
Web	O
sites	O
with	O
dynamic	O
content	O
can	O
use	O
URLs	O
that	O
generate	O
pages	O
from	O
the	O
server	O
using	O
query	B-Protocol
string	I-Protocol
parameters	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
URL	O
to	O
a	O
wiki	B-Protocol
page	O
with	O
title	O
Rewrite_engine	O
might	O
be	O
:	O
</s>
<s>
A	O
site	O
can	O
pass	O
specialized	O
terms	O
from	O
the	O
URL	O
to	O
its	O
search	B-Application
engine	I-Application
as	O
a	O
search	O
term	O
.	O
</s>
<s>
This	O
would	O
allow	O
users	B-General_Concept
to	O
search	O
directly	O
from	O
their	O
browser	O
.	O
</s>
<s>
Will	O
be	O
urlencoded	O
by	O
the	O
browser	O
before	O
it	O
makes	O
the	O
HTTP	B-Protocol
request	O
.	O
</s>
<s>
There	O
are	O
several	O
benefits	O
to	O
using	O
URL	B-Protocol
rewriting	I-Protocol
:	O
</s>
<s>
The	O
links	O
are	O
"	O
cleaner	O
"	O
and	O
more	O
descriptive	O
,	O
improving	O
their	O
"	O
friendliness	O
"	O
to	O
both	O
users	B-General_Concept
and	O
search	B-Application
engines	I-Application
.	O
</s>
<s>
There	O
can	O
,	O
however	O
be	O
drawbacks	O
as	O
well	O
;	O
if	O
a	O
user	O
wants	O
to	O
modify	O
a	O
URL	O
to	O
retrieve	O
new	O
data	O
,	O
URL	B-Protocol
rewriting	I-Protocol
may	O
hinder	O
the	O
construction	O
of	O
custom	O
queries	O
due	O
to	O
the	O
lack	O
of	O
named	O
variables	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
the	O
original	O
query	B-Protocol
string	I-Protocol
was	O
more	O
useful	O
,	O
since	O
the	O
query	O
variables	O
indicated	O
month	O
and	O
day	O
:	O
</s>
<s>
Many	O
web	B-Application
frameworks	I-Application
include	O
URL	B-Protocol
rewriting	I-Protocol
,	O
either	O
directly	O
or	O
through	O
extension	O
modules	O
.	O
</s>
<s>
Apache	B-Application
HTTP	I-Application
Server	I-Application
has	O
URL	B-Protocol
rewriting	I-Protocol
provided	O
by	O
the	O
mod_rewrite	O
module	O
.	O
</s>
<s>
URL	O
Rewrite	O
is	O
available	O
as	O
an	O
extension	O
to	O
Microsoft	B-Application
IIS	I-Application
.	O
</s>
<s>
Ruby	B-Application
on	I-Application
Rails	I-Application
has	O
built-in	O
URL	B-Protocol
rewriting	I-Protocol
via	O
Routes	O
.	O
</s>
<s>
Jakarta	B-Application
Servlet	I-Application
has	O
extendable	O
URL	B-Protocol
rewriting	I-Protocol
via	O
the	O
OCPsoft	O
URLRewriteFilter	O
and	O
Tuckey	O
UrlRewriteFilter	O
.	O
</s>
<s>
Jakarta	B-Language
Server	I-Language
Faces	I-Language
has	O
simplified	O
URL	B-Protocol
rewriting	I-Protocol
via	O
the	O
PrettyFaces	O
:	O
URLRewriteFilter	O
.	O
</s>
<s>
Django	B-Language
uses	O
a	O
regular-expressions-based	O
system	O
.	O
</s>
<s>
This	O
is	O
not	O
strictly	O
URL	B-Protocol
rewriting	I-Protocol
since	O
there	O
is	O
no	O
script	O
to	O
'	O
rewrite	O
 '	O
to	O
,	O
nor	O
even	O
a	O
directory	O
structure	O
;	O
but	O
it	O
provides	O
the	O
full	O
flexibility	O
of	O
URL	B-Protocol
rewriting	I-Protocol
.	O
</s>
<s>
Java	B-Language
Stripes	B-Language
Framework	I-Language
has	O
had	O
integrated	O
functionality	O
since	O
version	O
1.5	O
.	O
</s>
<s>
Many	O
Perl	O
frameworks	O
,	O
such	O
as	O
Mojolicious	B-Language
and	O
Catalyst	B-Language
,	O
have	O
this	O
feature	O
.	O
</s>
<s>
CodeIgniter	B-Language
has	O
URL	B-Protocol
rewriting	I-Protocol
provided	O
.	O
</s>
<s>
lighttpd	B-Protocol
has	O
a	O
mod_rewrite	O
module	O
.	O
</s>
<s>
nginx	B-Operating_System
has	O
a	O
rewrite	O
module	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
multi-link	O
multi-variable	O
page	O
generation	O
from	O
a	O
URI	B-Protocol
like	O
is	O
possible	O
,	O
where	O
multiple	O
individual	O
parts	O
like	O
get	O
expanded	O
with	O
the	O
help	O
of	O
regular	B-Language
expressions	I-Language
into	O
variables	O
to	O
signify	O
and	O
so	O
forth	O
.	O
</s>
<s>
Hiawatha	B-Application
HTTP	I-Application
server	I-Application
has	O
a	O
URL	O
Toolkit	O
which	O
supports	O
URL	B-Protocol
rewriting	I-Protocol
.	O
</s>
<s>
Cherokee	B-Language
HTTP	I-Language
server	I-Language
supports	O
regular	B-Language
expressions	I-Language
of	O
URL	B-Protocol
rewriting	I-Protocol
and	O
redirections	O
.	O
</s>
<s>
From	O
a	O
software	O
development	O
perspective	O
,	O
URL	B-Protocol
rewriting	I-Protocol
can	O
aid	O
in	O
code	O
modularization	O
and	O
control	O
flow	O
,	O
making	O
it	O
a	O
useful	O
feature	O
of	O
modern	O
web	B-Application
frameworks	I-Application
.	O
</s>
