<s>
ZK	B-Language
is	O
an	O
open-source	B-Application
Ajax	B-General_Concept
Web	B-Application
application	I-Application
framework	I-Application
,	O
written	O
in	O
Java	B-Language
,	O
that	O
enables	O
creation	O
of	O
graphical	B-Application
user	I-Application
interfaces	I-Application
for	O
Web	B-Application
applications	I-Application
with	O
little	O
required	O
programming	O
knowledge	O
.	O
</s>
<s>
The	O
core	O
of	O
ZK	B-Language
consists	O
of	O
an	O
Ajax-based	O
event-driven	B-Application
mechanism	O
,	O
over	O
123	O
XUL	B-Application
and	O
83	O
XHTML-based	O
components	O
,	O
and	O
a	O
mark-up	O
language	O
for	O
designing	O
user	O
interfaces	O
.	O
</s>
<s>
Programmers	O
design	O
their	O
application	O
pages	O
in	O
feature-rich	B-Architecture
XUL/XHTML	O
components	O
,	O
and	O
manipulate	O
them	O
upon	O
events	O
triggered	O
by	O
end	O
user	O
's	O
activity	O
.	O
</s>
<s>
It	O
is	O
similar	O
to	O
the	O
programming	O
model	O
found	O
in	O
desktop	O
GUI-based	O
applications	O
.	O
</s>
<s>
ZK	B-Language
uses	O
a	O
server-centric	O
approach	O
in	O
which	O
the	O
content	O
synchronization	O
of	O
components	O
and	O
the	O
event	O
pipe-lining	O
between	O
clients	O
and	O
servers	O
are	O
automatically	O
done	O
by	O
the	O
engine	O
,	O
and	O
Ajax	B-General_Concept
plumbing	O
codes	O
are	O
completely	O
transparent	O
to	O
web	B-Application
application	I-Application
developers	I-Application
.	O
</s>
<s>
ZK	B-Language
does	O
not	O
use	O
the	O
standard	O
web	O
request-response	B-Protocol
mechanism	O
and	O
does	O
not	O
send	O
form	O
fields	O
to	O
the	O
server	O
by	O
making	O
a	O
GET	O
request	O
with	O
query	O
parameters	O
or	O
a	O
POST	B-Protocol
request	I-Protocol
.	O
</s>
<s>
Instead	O
,	O
AJAX	B-General_Concept
requests	O
are	O
sent	O
to	O
the	O
server	O
to	O
update	O
the	O
internal	O
state	O
of	O
each	O
screen	O
widget	O
.	O
</s>
<s>
At	O
the	O
browser	O
,	O
ZK	B-Language
only	O
downloads	O
a	O
JSON	B-General_Concept
description	O
of	O
the	O
web	O
page	O
and	O
uses	O
a	O
client	O
renderer	O
to	O
turn	O
that	O
into	O
a	O
UI	O
.	O
</s>
<s>
The	O
optional	O
client-side	O
customization	O
allows	O
the	O
developer	O
to	O
leverage	O
the	O
client-side	O
resources	O
with	O
the	O
so-called	O
server+client	O
fusion	O
,	O
for	O
customization	O
and	O
to	O
reduce	O
the	O
Ajax	B-General_Concept
traffic	O
.	O
</s>
<s>
In	O
addition	O
to	O
component-based	O
programming	O
in	O
a	O
manner	O
similar	O
to	O
Swing	B-Language
,	O
ZK	B-Language
supports	O
a	O
mark-up	O
language	O
for	O
rich	O
user	O
interface	O
definition	O
called	O
ZUML	O
.	O
</s>
<s>
ZUML	O
allows	O
developers	O
to	O
meld	O
different	O
markup	O
languages	O
,	O
such	O
as	O
Mozilla	B-Operating_System
XUL	B-Application
language	O
and	O
XHTML	B-Language
,	O
seamlessly	O
into	O
the	O
same	O
page	O
.	O
</s>
<s>
ZUML	O
allows	O
developers	O
to	O
embed	O
scripts	O
in	O
pure	O
Java	B-Language
language	I-Language
(	O
interpreted	O
by	O
BeanShell	B-Language
)	O
and	O
use	O
EL	B-Language
expressions	O
to	O
manipulate	O
the	O
components	O
and	O
access	O
data	O
.	O
</s>
<s>
Simply	O
Java	B-Language
.	O
</s>
<s>
ZK	B-Language
is	O
renowned	O
for	O
its	O
"	O
Ajax	B-General_Concept
without	O
JavaScript	B-Language
"	O
approach	O
,	O
enabling	O
developers	O
to	O
build	O
rich	O
web	B-Application
applications	I-Application
transparently	O
without	O
any	O
knowledge	O
of	O
Ajax	B-General_Concept
and	O
JavaScript	B-Language
.	O
</s>
<s>
Over	O
100	O
Ajax	B-General_Concept
components	O
offer	O
UI	O
designers	O
a	O
variety	O
of	O
feature	O
rich	O
components	O
to	O
meet	O
the	O
demands	O
of	O
enterprise	O
Ajax	B-General_Concept
applications	O
.	O
</s>
<s>
ZUML	O
makes	O
the	O
design	O
of	O
rich	O
user	O
interfaces	O
similar	O
to	O
authoring	O
HTML	B-Language
pages	O
.	O
</s>
<s>
ZUML	O
is	O
a	O
variant	O
of	O
XUL	B-Application
inheriting	O
all	O
features	O
available	O
to	O
XML	O
,	O
and	O
separates	O
the	O
UI	O
definition	O
from	O
the	O
run-time	O
logic	O
.	O
</s>
<s>
Event-driven	B-Application
component-based	O
model	O
(	O
similar	O
to	O
desktop	O
programming	O
models	O
)	O
supporting	O
multiple	O
event	O
driven	O
GUI	B-Application
design	O
patterns	O
.	O
</s>
<s>
Embedding	O
scripting	O
support	O
with	O
Java	B-Language
(	O
Beanshell	B-Language
)	O
.	O
</s>
<s>
Optional	O
support	O
for	O
other	O
serverside	O
Java	B-Language
scripting	O
in	O
other	O
languages	O
such	O
as	O
JavaScript	B-Language
(	O
Rhino	B-Language
)	O
,	O
Ruby	B-Language
(	O
JRuby	B-Language
)	O
,	O
Python	B-Language
(	O
Jython	B-Language
)	O
and	O
Groovy	B-Application
.	O
</s>
<s>
Support	O
for	O
integrating	O
with	O
existing	O
web	B-Application
frameworks	I-Application
via	O
a	O
JSP	O
custom	O
tag	O
library	O
,	O
JSF	O
support	O
,	O
Portlet	O
,	O
and	O
a	O
Servlet	B-Application
Filter	O
.	O
</s>
<s>
ZK	B-Language
is	O
a	O
server	O
side	O
framework	O
which	O
emits	O
HTML	B-Language
and	O
thus	O
does	O
not	O
depend	O
on	O
client	O
side	O
presence	O
of	O
Gecko	B-Language
making	O
it	O
portable	O
to	O
any	O
browser	O
.	O
</s>
<s>
ZK	B-Language
takes	O
ZUML	O
(	O
xul	B-Application
and	O
xhtml	B-Language
)	O
serverside	O
pages	O
as	O
input	O
and	O
outputs	O
dhtml	O
for	O
the	O
browser	O
.	O
</s>
<s>
ZK	B-Language
processes	O
user	O
interface	O
logic	O
on	O
the	O
server	O
in	O
Java	B-Language
.	O
</s>
<s>
While	O
ZK	B-Language
and	O
XUL	B-Application
have	O
an	O
overlapping	O
subset	O
of	O
components	O
,	O
ZK	B-Language
has	O
its	O
own	O
unique	O
component	O
sets	O
.	O
</s>
<s>
ZK	B-Language
provides	O
serverside	O
databinding	O
annotations	O
to	O
declaratively	O
bind	O
UI	O
components	O
to	O
serverside	O
data	O
.	O
</s>
<s>
ZUML	O
(	O
ZK	B-Language
User	O
Interface	O
Markup	O
Language	O
)	O
is	O
a	O
markup	O
language	O
for	O
rich	O
user	O
interfaces	O
definition	O
.	O
</s>
<s>
ZUML	O
allows	O
developer	O
to	O
meld	O
different	O
markup	O
languages	O
,	O
such	O
as	O
Mozilla	B-Operating_System
XUL	B-Application
language	O
and	O
XHTML	B-Language
,	O
seamlessly	O
into	O
the	O
same	O
page	O
.	O
</s>
<s>
ZUML	O
allows	O
developers	O
to	O
embed	O
script	O
in	O
pure	O
Java	B-Language
language	I-Language
(	O
interpreted	O
by	O
BeanShell	B-Language
)	O
and	O
use	O
EL	B-Language
expressions	O
to	O
manipulate	O
the	O
components	O
and	O
access	O
data	O
.	O
</s>
<s>
ZUML	O
is	O
supported	O
by	O
ZK	B-Language
.	O
</s>
<s>
ZK	B-Language
is	O
a	O
server-centric	O
framework	O
.	O
</s>
<s>
It	O
is	O
how	O
ZK	B-Language
Mobile	O
running	O
on	O
Java	B-Language
Mobile	O
VM	O
is	O
done	O
.	O
</s>
<s>
Since	O
ZK	B-Language
5.0	O
,	O
the	O
so-called	O
Server+client	O
Fusion	O
architecture	O
is	O
introduced	O
.	O
</s>
<s>
ZK	B-Language
Client	O
Engine	O
is	O
based	O
on	O
jQuery	B-Language
.	O
</s>
<s>
Technically	O
you	O
can	O
use	O
jQuery-compliant	O
libraries	O
and	O
widgets	O
.	O
</s>
