<s>
Apache	B-Language
Click	I-Language
is	O
a	O
page	O
and	O
component	O
oriented	O
web	B-Application
application	I-Application
framework	I-Application
for	O
the	O
Java	B-Language
language	I-Language
and	O
is	O
built	O
on	O
top	O
of	O
the	B-Application
Java	I-Application
Servlet	I-Application
API	I-Application
.	O
</s>
<s>
It	O
is	O
a	O
free	O
and	O
open-source	B-Application
project	O
distributed	O
under	O
the	O
Apache	B-Application
license	I-Application
and	O
runs	O
on	O
any	O
JDK	B-Language
installation	O
(	O
1.5	O
or	O
later	O
)	O
.	O
</s>
<s>
The	O
project	O
was	O
retired	B-Application
in	O
May	O
2014	O
.	O
</s>
<s>
The	B-Application
Java	I-Application
Servlet	I-Application
API	I-Application
is	O
fully	O
exposed	O
to	O
the	O
developer	O
which	O
eases	O
the	O
upgrade	O
path	O
from	O
an	O
action	O
based	O
framework	O
to	O
a	O
component	O
based	O
one	O
.	O
</s>
<s>
Pages	O
and	O
components	O
are	O
developed	O
in	O
Java	B-Language
while	O
templates	O
can	O
be	O
written	O
in	O
Velocity	B-Language
,	O
FreeMarker	B-Language
or	O
JSP	B-Language
.	O
</s>
<s>
A	O
major	O
difference	O
between	O
Click	O
and	O
other	O
component	O
oriented	O
web	B-Application
frameworks	I-Application
is	O
that	O
Click	O
is	O
stateless	O
by	O
design	O
,	O
although	O
stateful	O
pages	O
are	O
supported	O
.	O
</s>
<s>
There	O
are	O
a	O
number	O
of	O
other	O
component	O
oriented	O
frameworks	O
available	O
for	O
Java	B-Language
such	O
as	O
JSF	B-Language
,	O
Tapestry	B-Language
,	O
WebObjects	B-Language
,	O
Apache	B-Language
Wicket	I-Language
and	O
Vaadin	B-Language
.	O
</s>
<s>
Some	O
developers	O
prefer	O
the	O
more	O
traditional	O
action-based	O
web	B-Application
frameworks	I-Application
including	O
Apache	B-Language
Struts	I-Language
,	O
Spring	B-Application
MVC	I-Application
,	O
and	O
Stripes	B-Language
.	O
</s>
<s>
The	O
default	O
template	O
engine	O
for	O
Click	O
is	O
Velocity	B-Language
,	O
the	O
htm	B-Language
file	I-Language
will	O
be	O
similar	O
to	O
a	O
normal	O
,	O
static	O
HTML	B-Language
page	O
.	O
</s>
<s>
The	O
servlet	B-Application
application	O
definition	O
.	O
</s>
