<s>
Ultra-large-scale	O
system	O
(	O
ULSS	O
)	O
is	O
a	O
term	O
used	O
in	O
fields	O
including	O
Computer	B-General_Concept
Science	I-General_Concept
,	O
Software	B-General_Concept
Engineering	I-General_Concept
and	O
Systems	O
Engineering	O
to	O
refer	O
to	O
software	O
intensive	O
systems	O
with	O
unprecedented	O
amounts	O
of	O
hardware	O
,	O
lines	O
of	O
source	O
code	O
,	O
numbers	O
of	O
users	O
,	O
and	O
volumes	O
of	O
data	O
.	O
</s>
<s>
The	O
term	O
ultra-large-scale	O
system	O
was	O
introduced	O
in	O
a	O
2006	O
report	O
from	O
the	O
Software	B-General_Concept
Engineering	I-General_Concept
Institute	O
at	O
Carnegie	O
Mellon	O
University	O
authored	O
by	O
Linda	O
Northrop	O
and	O
colleagues	O
.	O
</s>
<s>
Many	O
of	O
the	O
challenges	O
recognized	O
in	O
this	O
initiative	O
were	O
the	O
same	O
as	O
,	O
or	O
were	O
similar	O
to	O
those	O
recognized	O
as	O
the	O
challenges	O
of	O
ultra-large-scale	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
This	O
seems	O
to	O
have	O
led	O
to	O
there	O
being	O
two	O
slightly	O
different	O
perspectives	O
on	O
ultra-large-scale	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
Richard	O
Gabriel	O
's	O
perspective	O
is	O
that	O
ultra-large-scale	B-General_Concept
systems	I-General_Concept
are	O
desirable	O
but	O
currently	O
impossible	O
to	O
build	O
due	O
to	O
limitations	O
in	O
the	O
fields	O
of	O
software	O
design	O
and	O
systems	O
engineering	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
Ian	O
Sommerville	O
's	O
perspective	O
is	O
that	O
ultra-large-scale	B-General_Concept
systems	I-General_Concept
are	O
already	O
emerging	O
(	O
for	O
example	O
in	O
air	O
traffic	O
control	O
)	O
,	O
the	O
key	O
problem	O
being	O
not	O
how	O
to	O
achieve	O
them	O
but	O
how	O
to	O
ensure	O
they	O
are	O
adequately	O
engineered	O
.	O
</s>
<s>
Ultra-large-scale	B-General_Concept
systems	I-General_Concept
hold	O
the	O
characteristics	O
of	O
systems	O
of	O
systems	O
(	O
systems	O
that	O
have	O
:	O
operationally	O
independent	O
sub-systems	O
;	O
managerially	O
independent	O
components	O
and	O
sub-systems	O
;	O
evolutionary	O
development	O
;	O
emergent	O
behavior	O
;	O
and	O
geographic	O
distribution	O
)	O
.	O
</s>
<s>
Other	O
domains	O
said	O
to	O
be	O
seeing	O
the	O
rise	O
of	O
ultra-large-scale	B-General_Concept
systems	I-General_Concept
include	O
government	O
,	O
transport	O
systems	O
(	O
for	O
example	O
air	O
traffic	O
control	O
systems	O
)	O
,	O
energy	O
distribution	O
systems	O
(	O
for	O
example	O
smart	O
grids	O
)	O
and	O
large	O
enterprises	O
.	O
</s>
