<s>
Gazelle	B-Protocol
was	O
a	O
research	O
web	B-Application
browser	I-Application
project	O
by	O
Microsoft	O
Research	O
,	O
first	O
announced	O
in	O
early	O
2009	O
.	O
</s>
<s>
The	O
central	O
notion	O
of	O
the	O
project	O
was	O
to	O
apply	O
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
principles	O
to	O
browser	B-Application
construction	O
.	O
</s>
<s>
In	O
particular	O
,	O
the	O
browser	B-Application
had	O
a	O
secure	O
kernel	B-Operating_System
,	O
modeled	O
after	O
an	O
OS	B-Operating_System
kernel	I-Operating_System
,	O
and	O
various	O
web	O
sources	O
run	O
as	O
separate	O
"	O
principals	O
"	O
above	O
that	O
,	O
similar	O
to	O
user	B-Operating_System
space	I-Operating_System
processes	O
in	O
an	O
OS	O
.	O
</s>
<s>
Browser	B-Application
plugins	B-Application
are	O
also	O
managed	O
as	O
principals	O
.	O
</s>
<s>
Gazelle	B-Protocol
had	O
a	O
predecessor	O
project	O
,	O
MashupOS	O
,	O
but	O
with	O
Gazelle	B-Protocol
the	O
emphasis	O
was	O
on	O
a	O
more	O
secure	O
browser	B-Application
.	O
</s>
<s>
By	O
the	O
July	O
2009	O
announcement	O
of	O
ChromeOS	B-Operating_System
,	O
Gazelle	B-Protocol
was	O
seen	O
as	O
a	O
possible	O
alternative	O
Microsoft	O
architectural	O
approach	O
compared	O
to	O
Google	O
's	O
direction	O
.	O
</s>
<s>
That	O
is	O
,	O
rather	O
than	O
the	O
OS	O
being	O
reduced	O
in	O
role	O
to	O
that	O
of	O
a	O
browser	B-Application
,	O
the	O
browser	B-Application
would	O
be	O
strengthened	O
using	O
OS	O
principles	O
.	O
</s>
<s>
The	O
Gazelle	B-Protocol
project	O
became	O
dormant	O
,	O
and	O
ServiceOS	O
arose	O
as	O
a	O
replacement	O
project	O
also	O
related	O
to	O
browser	B-Application
architectures	O
.	O
</s>
<s>
But	O
by	O
2015	O
,	O
the	O
SecureOS	O
project	O
was	O
also	O
dormant	O
,	O
after	O
Microsoft	O
decided	O
that	O
its	O
new	O
flagship	O
browser	B-Application
would	O
be	O
Edge	B-Application
.	O
</s>
