<s>
The	O
Jakarta	B-Language
Expression	I-Language
Language	I-Language
(	O
EL	O
;	O
formerly	O
Expression	O
Language	O
and	O
Unified	B-Language
Expression	I-Language
Language	I-Language
)	O
is	O
a	O
special	B-Language
purpose	I-Language
programming	I-Language
language	I-Language
mostly	O
used	O
in	O
Jakarta	B-Language
EE	I-Language
web	O
applications	O
for	O
embedding	O
and	O
evaluating	O
expressions	O
in	O
web	O
pages	O
.	O
</s>
<s>
The	O
specification	O
writers	O
and	O
expert	O
groups	O
of	O
the	O
Java	B-Language
EE	I-Language
web-tier	O
technologies	O
have	O
worked	O
on	O
a	O
unified	B-Language
expression	I-Language
language	I-Language
which	O
was	O
first	O
included	O
in	O
the	O
JSP	B-Language
2.1	I-Language
specification	O
(	O
JSR-245	O
)	O
,	O
and	O
later	O
specified	O
by	O
itself	O
in	O
JSR-341	O
,	O
part	O
of	O
Java	B-Language
EE	I-Language
7	I-Language
.	O
</s>
<s>
The	O
expression	O
language	O
started	O
out	O
as	O
part	O
of	O
the	O
JavaServer	B-Language
Pages	I-Language
Standard	I-Language
Tag	I-Language
Library	I-Language
(	O
JSTL	B-Language
)	O
and	O
was	O
originally	O
called	O
SPEL	O
(	O
Simplest	O
Possible	O
Expression	O
Language	O
)	O
,	O
then	O
just	O
Expression	O
Language	O
(	O
EL	O
)	O
.	O
</s>
<s>
It	O
was	O
a	O
scripting	O
language	O
which	O
allowed	O
access	O
to	O
Java	B-Device
components	O
(	O
JavaBeans	O
)	O
through	O
JSP	B-Language
.	O
</s>
<s>
Since	O
JSP	B-Language
2.0	O
,	O
it	O
has	O
been	O
used	O
inside	O
JSP	B-Language
tags	O
to	O
separate	O
Java	B-Device
code	O
from	O
JSP	B-Language
,	O
and	O
to	O
allow	O
easier	O
access	O
to	O
Java	B-Device
components	O
(	O
than	O
in	O
Java	B-Device
code	O
)	O
.	O
</s>
<s>
Over	O
the	O
years	O
,	O
the	O
expression	O
language	O
has	O
evolved	O
to	O
include	O
more	O
advanced	O
functionality	O
and	O
it	O
was	O
included	O
in	O
the	O
JSP	B-Language
2.0	O
specification	O
.	O
</s>
<s>
Scripting	O
was	O
made	O
easier	O
for	O
web-content	O
designers	O
who	O
have	O
little	O
or	O
practically	O
no	O
knowledge	O
of	O
the	O
core	O
Java	B-Device
Language	O
.	O
</s>
<s>
This	O
scripting	O
language	O
made	O
JSP	B-Language
a	O
scripting	O
language	O
in	O
the	O
true	O
sense	O
.	O
</s>
<s>
Before	O
EL	O
,	O
JSP	B-Language
consisted	O
of	O
some	O
special	O
tags	O
like	O
scriptlets	B-Language
,	O
expressions	O
etc	O
.	O
</s>
<s>
within	O
which	O
Java	B-Device
code	O
was	O
written	O
explicitly	O
.	O
</s>
<s>
With	O
EL	O
the	O
web-content	O
designer	O
needs	O
only	O
to	O
know	O
how	O
to	O
make	O
proper	O
calls	O
to	O
core	O
Java	B-Device
methods	O
.	O
</s>
<s>
EL	O
was	O
,	O
both	O
syntactically	O
and	O
semantically	O
,	O
similar	O
to	O
JavaScript	B-Language
expressions	O
:	O
</s>
<s>
EL	O
also	O
liberated	B-Application
the	O
programmer	O
from	O
having	O
to	O
know	O
the	O
particularities	O
of	O
how	O
the	O
values	O
are	O
actually	O
accessed	O
:	O
object.property	O
can	O
mean	O
(	O
depending	O
on	O
what	O
the	O
object	O
is	O
)	O
either	O
object.get("property" )	O
or	O
object.getProperty("property" )	O
or	O
object.getProperty( )	O
etc	O
.	O
</s>
<s>
During	O
the	O
development	O
of	O
JSP	B-Language
2.0	O
,	O
the	O
JavaServer	B-Language
Faces	I-Language
technology	O
was	O
released	O
which	O
also	O
needed	O
an	O
expression	O
language	O
,	O
but	O
the	O
expression	O
language	O
defined	O
in	O
the	O
JSP	B-Language
2.0	O
specification	O
did	O
n't	O
satisfy	O
all	O
the	O
needs	O
for	O
development	O
with	O
JSF	O
technology	O
.	O
</s>
<s>
But	O
developers	O
had	O
problems	O
when	O
integrating	O
the	O
JSP	B-Language
EL	O
with	O
the	O
JSF	O
EL	O
because	O
of	O
conflicts	O
.	O
</s>
<s>
Because	O
of	O
these	O
incompatibilities	O
,	O
the	O
unified	B-Language
expression	I-Language
language	I-Language
initiative	O
was	O
started	O
to	O
unify	O
these	O
expression	O
languages	O
.	O
</s>
<s>
As	O
of	O
JSP	B-Language
2.1	I-Language
,	O
the	O
expression	O
languages	O
of	O
JSP	B-Language
2.0	O
and	O
JSF	O
1.1	O
have	O
been	O
merged	O
into	O
a	O
single	O
unified	B-Language
expression	I-Language
language	I-Language
(	O
EL	O
2.1	O
)	O
.	O
</s>
<s>
Version	O
3.0	O
of	O
the	O
expression	O
language	O
(	O
the	O
unified	O
was	O
no	O
longer	O
deemed	O
necessary	O
)	O
was	O
developed	O
in	O
a	O
JSR	O
independent	O
of	O
the	O
JSP	B-Language
and	O
JSF	O
specifications	O
in	O
.	O
</s>
<s>
Some	O
new	O
features	O
were	O
added	O
,	O
most	O
notably	O
EL	O
equivalents	O
of	O
Java	B-Device
8	O
streams	O
and	O
lambda	O
expressions	O
.	O
</s>
<s>
The	O
API	O
moved	O
from	O
the	O
javax.el	O
package	O
to	O
the	O
jakarta.el	O
package	O
,	O
as	O
part	O
of	O
the	O
transition	O
from	O
Java	B-Language
EE	I-Language
to	O
Jakarta	B-Language
EE	I-Language
.	O
</s>
<s>
The	O
unified	O
EL	O
is	O
a	O
union	O
of	O
the	O
JSP	B-Language
and	O
JSF	O
expression	O
languages	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
features	O
already	O
available	O
in	O
the	O
JSP	B-Language
EL	O
,	O
the	O
unified	O
EL	O
has	O
the	O
following	O
features	O
:	O
</s>
<s>
This	O
shows	O
a	O
simple	O
example	O
of	O
Unified	O
EL	O
being	O
used	O
within	O
a	O
JSTL	B-Language
"	O
c:out	O
"	O
tag	O
:	O
</s>
<s>
is	O
a	O
library	O
intended	O
to	O
facilitate	O
the	O
implementation	O
of	O
dynamic	O
and	O
scripting	O
features	O
in	O
applications	O
and	O
frameworks	O
written	O
in	O
Java	B-Device
.	O
</s>
<s>
is	O
an	O
open-source	B-Application
implementation	O
of	O
the	O
Unified	B-Language
Expression	I-Language
Language	I-Language
(	O
EL	O
)	O
,	O
specified	O
as	O
part	O
of	O
the	O
JSP	B-Language
2.1	I-Language
standard	O
(	O
JSR-245	O
)	O
.	O
</s>
<s>
It	O
is	O
considered	O
stable	O
and	O
feature	O
complete	O
and	O
is	O
licensed	O
under	O
the	O
Apache	B-Application
License	I-Application
2.0	I-Application
.	O
</s>
<s>
JUEL	B-Language
is	O
also	O
suitable	O
for	O
use	O
in	O
non-JSP	O
applications	O
.	O
</s>
<s>
is	O
the	O
JSP	B-Language
2.0	O
EL	O
interpreter	O
from	O
Apache	O
.	O
</s>
