<s>
Rhino	B-Language
is	O
a	O
JavaScript	B-Language
engine	I-Language
written	O
fully	O
in	O
Java	B-Language
and	O
managed	O
by	O
the	B-Operating_System
Mozilla	I-Operating_System
Foundation	I-Operating_System
as	O
open	B-Application
source	I-Application
software	I-Application
.	O
</s>
<s>
It	O
is	O
separate	O
from	O
the	O
SpiderMonkey	B-Language
engine	O
,	O
which	O
is	O
also	O
developed	O
by	O
Mozilla	O
,	O
but	O
written	O
in	O
C++	B-Language
and	O
used	O
in	O
Mozilla	B-Application
Firefox	I-Application
.	O
</s>
<s>
The	O
Rhino	B-Language
project	I-Language
was	O
started	O
at	O
Netscape	O
in	O
1997	O
.	O
</s>
<s>
At	O
the	O
time	O
,	O
Netscape	O
was	O
planning	O
to	O
produce	O
a	O
version	O
of	O
Netscape	B-Protocol
Navigator	I-Protocol
written	O
fully	O
in	O
Java	B-Language
and	O
so	O
it	O
needed	O
an	O
implementation	O
of	O
JavaScript	B-Language
written	O
in	O
Java	B-Language
.	O
</s>
<s>
When	O
Netscape	O
stopped	O
work	O
on	O
Javagator	O
,	O
as	O
it	O
was	O
called	O
,	O
the	O
Rhino	B-Language
project	I-Language
was	O
finished	O
as	O
a	O
JavaScript	B-Language
engine	I-Language
.	O
</s>
<s>
Since	O
then	O
,	O
a	O
couple	O
of	O
major	O
companies	O
(	O
including	O
Sun	O
Microsystems	O
)	O
have	O
licensed	O
Rhino	B-Language
for	O
use	O
in	O
their	O
products	O
and	O
paid	O
Netscape	O
to	O
do	O
so	O
,	O
allowing	O
work	O
to	O
continue	O
on	O
it	O
.	O
</s>
<s>
Originally	O
,	O
Rhino	B-Language
compiled	B-Language
all	O
JavaScript	B-Language
code	O
to	O
Java	B-Language
bytecode	I-Language
in	O
generated	O
Java	B-Language
class	I-Language
files	I-Language
.	O
</s>
<s>
This	O
produced	O
the	O
best	O
performance	O
,	O
often	O
beating	O
the	O
C++	B-Language
implementation	O
of	O
JavaScript	B-Language
run	O
with	O
just-in-time	O
compilation	B-Language
(	O
JIT	O
)	O
,	O
but	O
suffered	O
from	O
two	O
faults	O
.	O
</s>
<s>
First	O
,	O
compiling	B-Language
time	O
was	O
long	O
since	O
generating	O
bytecode	O
and	O
loading	O
the	O
generated	O
classes	O
was	O
a	O
resource-intensive	O
process	O
.	O
</s>
<s>
Also	O
,	O
the	O
implementation	O
effectively	O
leaked	B-Error_Name
memory	I-Error_Name
since	O
most	O
Java	B-Language
virtual	I-Language
machines	I-Language
(	O
JVM	B-Language
)	O
did	O
n't	O
collect	B-General_Concept
unused	O
classes	O
or	O
the	O
strings	O
that	O
are	O
interned	O
as	O
a	O
result	O
of	O
loading	O
a	O
class	B-Language
file	I-Language
.	O
</s>
<s>
(	O
This	O
has	O
changed	O
in	O
later	O
versions	O
of	O
Java	B-Language
.	O
)	O
</s>
<s>
As	O
a	O
result	O
,	O
in	O
the	O
fall	O
of	O
1998	O
,	O
Rhino	B-Language
added	O
an	O
interpretive	O
mode	O
.	O
</s>
<s>
The	O
classfile	B-Language
generation	O
code	O
was	O
moved	O
to	O
an	O
optional	O
,	O
dynamically	B-Operating_System
loaded	I-Operating_System
package	O
.	O
</s>
<s>
Compiling	B-Language
is	O
faster	O
and	O
when	O
scripts	O
are	O
no	O
longer	O
in	O
use	O
they	O
can	O
be	O
collected	O
like	O
any	O
other	O
Java	B-Language
object	O
.	O
</s>
<s>
Rhino	B-Language
was	O
released	O
to	O
Mozilla	B-Operating_System
Foundation	I-Operating_System
in	O
April	O
1998	O
.	O
</s>
<s>
Originally	O
Rhino	B-Language
classfile	B-Language
generation	O
had	O
been	O
held	O
back	O
from	O
release	O
.	O
</s>
<s>
However	O
the	O
licensors	O
of	O
Rhino	B-Language
have	O
now	O
agreed	O
to	O
release	O
all	O
of	O
Rhino	B-Language
as	O
open	B-Application
source	I-Application
,	O
including	O
class	B-Language
file	I-Language
generation	O
.	O
</s>
<s>
Since	O
its	O
release	O
to	O
open	B-Application
source	I-Application
,	O
Rhino	B-Language
has	O
found	O
a	O
variety	O
of	O
uses	O
and	O
an	O
increasing	O
number	O
of	O
people	O
have	O
contributed	O
to	O
the	O
code	O
.	O
</s>
<s>
The	O
project	O
gets	O
its	O
name	O
from	O
the	O
animal	O
on	O
the	O
cover	O
of	O
the	O
JavaScript	B-Language
book	O
from	O
O'Reilly	O
Media	O
.	O
</s>
<s>
As	O
of	O
version	O
1.7R11	O
(	O
May	O
2019	O
)	O
,	O
Rhino	B-Language
supports	O
Java	B-Language
8	O
and	O
up	O
,	O
and	O
supports	O
a	O
number	O
of	O
ECMAScript	B-Language
ES6/ES2015	O
features	O
.	O
</s>
<s>
Rhino	B-Language
converts	O
JavaScript	B-Language
scripts	O
into	O
classes	O
.	O
</s>
<s>
Rhino	B-Language
works	O
in	O
both	O
compiled	B-Language
and	O
interpreted	B-Application
mode	O
.	O
</s>
<s>
It	O
is	O
intended	O
to	O
be	O
used	O
in	O
desktop	O
or	O
server-side	B-Application
applications	O
,	O
hence	O
there	O
is	O
no	O
built-in	O
support	O
for	O
the	O
Web	B-Application
browser	I-Application
objects	O
that	O
are	O
commonly	O
associated	O
with	O
JavaScript	B-Language
.	O
</s>
<s>
Rhino	B-Language
can	O
be	O
used	O
as	O
a	O
debugger	B-Application
by	O
using	O
the	O
Rhino	B-Language
shell	B-Application
.	O
</s>
<s>
The	O
JavaScript	B-Language
shell	B-Application
provides	O
a	O
simple	O
way	O
to	O
run	O
scripts	O
in	O
batch	O
mode	O
or	O
within	O
an	O
interactive	O
environment	O
for	O
exploratory	O
programming	O
.	O
</s>
<s>
It	O
can	O
be	O
used	O
in	O
applications	O
by	O
embedding	O
Rhino	B-Language
.	O
</s>
<s>
A	O
slightly	O
modified	O
version	O
of	O
Rhino	B-Language
1.6r2	O
comes	O
bundled	O
with	O
the	O
Sun	O
Microsystems	O
release	O
of	O
Java	B-Language
SE	I-Language
version	O
6	O
,	O
which	O
was	O
released	O
in	O
December	O
2006	O
.	O
</s>
<s>
This	O
makes	O
it	O
easier	O
to	O
integrate	O
JavaScript	B-Language
as	O
part	O
of	O
Java	B-Language
programs	O
and	O
to	O
access	O
Java	B-Language
resources	O
from	O
JavaScript	B-Language
.	O
</s>
<s>
Other	O
implementations	O
of	O
Java	B-Language
6	O
may	O
differ	O
.	O
</s>
