<s>
XAML	B-Application
Browser	I-Application
Applications	I-Application
(	O
XBAP	B-Application
,	O
pronounced	O
"	O
ex-bap	O
"	O
)	O
are	O
Windows	B-Device
Presentation	I-Device
Foundation	I-Device
(	O
.xbap	O
)	O
applications	O
that	O
are	O
hosted	O
and	O
run	O
inside	O
a	O
web	B-Application
browser	I-Application
such	O
as	O
Firefox	B-Application
or	O
Internet	B-Application
Explorer	I-Application
.	O
</s>
<s>
Hosted	O
applications	O
run	O
in	O
a	O
partial	O
trust	O
sandbox	O
environment	O
and	O
are	O
not	O
given	O
full	O
access	O
to	O
the	O
computer	O
's	O
resources	O
like	O
opening	O
a	O
new	O
network	O
connection	O
or	O
saving	O
a	O
file	O
to	O
the	O
computer	O
disk	O
and	O
not	O
all	O
WPF	B-Device
functionality	O
is	O
available	O
.	O
</s>
<s>
Starting	O
an	O
XBAP	B-Application
from	O
an	O
HTML	B-Language
page	O
is	O
seamless	O
(	O
with	O
no	O
security	O
or	O
installation	O
prompt	O
)	O
.	O
</s>
<s>
Although	O
one	O
perceives	O
the	O
application	O
running	O
in	O
the	O
browser	B-Application
,	O
it	O
actually	O
runs	O
in	O
an	O
out-of-process	O
executable	O
(	O
PresentationHost.exe	O
)	O
managed	O
by	O
a	O
virtual	O
machine	O
.	O
</s>
<s>
In	O
the	O
initial	O
release	O
of	O
.NET	B-Application
Framework	I-Application
3.0	I-Application
,	O
XBAPs	B-Application
only	O
ran	O
in	O
Internet	B-Application
Explorer	I-Application
.	O
</s>
<s>
With	O
the	O
release	O
of	O
.NET	B-Application
Framework	I-Application
3.5	I-Application
SP1	I-Application
,	O
which	O
includes	O
an	O
XBAP	B-Application
extension	O
,	O
they	O
also	O
run	O
in	O
Mozilla	B-Application
Firefox	I-Application
.	O
</s>
<s>
XBAP	B-Application
applications	O
have	O
certain	O
restrictions	O
on	O
what	O
.NET	B-Application
features	O
they	O
can	O
use	O
.	O
</s>
<s>
Nearly	O
all	O
standard	O
WPF	B-Device
functionality	O
,	O
however	O
,	O
around	O
99%	O
,	O
is	O
available	O
to	O
an	O
XBAP	B-Application
application	O
.	O
</s>
<s>
Therefore	O
,	O
most	O
of	O
the	O
WPF	B-Device
UI	B-Application
features	O
are	O
available	O
.	O
</s>
<s>
Starting	O
in	O
February	O
2009	O
,	O
XBAP	B-Application
applications	O
no	O
longer	O
function	O
when	O
run	O
from	O
the	O
Internet	O
.	O
</s>
<s>
Attempting	O
to	O
run	O
the	O
XBAP	B-Application
will	O
cause	O
the	O
browser	B-Application
to	O
present	O
a	O
generic	O
error	O
message	O
.	O
</s>
<s>
An	O
option	O
exists	O
in	O
Internet	B-Application
Explorer	I-Application
9	O
that	O
can	O
be	O
used	O
to	O
allow	O
the	O
applications	O
to	O
run	O
,	O
but	O
this	O
must	O
be	O
done	O
with	O
care	O
as	O
it	O
increases	O
the	O
potential	O
attack	O
surface	O
-	O
and	O
there	O
have	O
been	O
security	O
vulnerabilities	O
in	O
XBAP	B-Application
.	O
</s>
