<s>
GStat	B-Operating_System
is	O
a	O
web	O
application	O
which	O
is	O
aimed	O
at	O
displaying	O
information	O
about	O
grid	O
services	O
,	O
the	O
grid	O
information	O
system	O
itself	O
and	O
related	O
metrics	O
.	O
</s>
<s>
Gstat	B-Operating_System
has	O
evolved	O
over	O
the	O
past	O
few	O
years	O
from	O
a	O
simple	O
CGI	O
script	O
that	O
displayed	O
the	O
summary	O
of	O
a	O
grid	O
infrastructure	O
to	O
a	O
production	O
quality	O
service	O
providing	O
rich	O
features	O
such	O
as	O
information	O
content	O
testing	O
and	O
infrastructure	O
monitoring	O
.	O
</s>
<s>
An	O
evolutionary	O
approach	O
to	O
its	O
development	O
has	O
enabled	O
GStat	B-Operating_System
to	O
add	O
functionally	O
in	O
response	O
to	O
real	O
use	O
cases	O
and	O
to	O
become	O
a	O
key	O
operational	O
tool	O
.	O
</s>
<s>
GStat	B-Operating_System
2.0	O
is	O
a	O
major	O
redesign	O
of	O
the	O
original	O
version	O
which	O
will	O
ensure	O
that	O
it	O
will	O
meet	O
the	O
future	O
demands	O
of	O
an	O
evolving	O
infrastructure	O
and	O
easily	O
integrate	O
with	O
other	O
operational	O
tools	O
.	O
</s>
<s>
GStat	B-Operating_System
is	O
the	O
result	O
of	O
a	O
collaboration	O
between	O
Academia	O
Sinica	O
and	O
the	O
Grid	O
Technology	O
Group	O
at	O
CERN	O
.	O
</s>
<s>
The	O
main	O
purpose	O
of	O
the	O
joint	O
project	O
is	O
to	O
align	O
GStat	B-Operating_System
with	O
direction	O
taken	O
by	O
the	O
WLCG	O
monitoring	O
group	O
with	O
respect	O
to	O
operational	O
tools	O
and	O
in	O
addition	O
ensure	O
that	O
GStat	B-Operating_System
can	O
make	O
a	O
contribution	O
to	O
middleware	O
certification	O
and	O
site	O
validation	O
.	O
</s>
<s>
GStat	B-Operating_System
is	O
compatible	O
with	O
version	O
1.3	O
of	O
the	O
Grid	O
Laboratory	O
Uniform	O
Environment	O
data	O
model	O
,	O
taking	O
the	O
information	O
of	O
existing	O
Berkeley	B-Application
Database	I-Application
Information	I-Application
Index	I-Application
instances	O
.	O
</s>
<s>
The	O
initial	O
version	O
of	O
GStat	B-Operating_System
were	O
designed	O
and	O
developed	O
by	O
Min	O
Tsai	O
.	O
</s>
<s>
GStat	B-Operating_System
provides	O
a	O
method	O
to	O
visualize	O
a	O
grid	O
infrastructure	O
from	O
an	O
operational	O
perspective	O
based	O
on	O
information	O
found	O
in	O
the	O
grid	O
information	O
system	O
.	O
</s>
<s>
The	O
existence	O
of	O
grid	O
services	O
and	O
the	O
communication	O
of	O
their	O
existence	O
defines	O
the	O
grid	O
infrastructures	O
and	O
as	O
such	O
one	O
of	O
the	O
main	O
concepts	O
in	O
GStat	B-Operating_System
2.0	O
is	O
this	O
is	O
should	O
be	O
bootstrapped	O
by	O
the	O
information	O
system	O
endpoint	O
that	O
defines	O
the	O
view	O
of	O
the	O
grid	O
infrastructure	O
.	O
</s>
<s>
The	O
GStat	B-Operating_System
architecture	O
makes	O
a	O
clear	O
separation	O
between	O
data	O
,	O
infrastructure	O
monitoring	O
,	O
content	O
validation	O
and	O
visualization	O
.	O
</s>
<s>
Gstat	B-Operating_System
is	O
uniquely	O
positioned	O
to	O
support	O
modern	O
day	O
Big	O
Data	O
initiatives	O
.	O
</s>
<s>
The	O
GStat	B-Operating_System
architecture	O
is	O
implemented	O
using	O
two	O
main	O
frameworks	O
;	O
Django	B-Language
and	O
Nagios	B-Application
.	O
</s>
<s>
Django	B-Language
is	O
an	O
open	O
source	O
web	O
application	O
framework	O
,	O
written	O
in	O
Python	B-Language
,	O
which	O
follows	O
the	O
model	O
–	O
view	O
–	O
controller	O
architectural	O
pattern	O
.	O
</s>
<s>
Django	B-Language
models	O
are	O
used	O
to	O
provide	O
the	O
core	O
data	O
model	O
of	O
the	O
system	O
.	O
</s>
<s>
The	O
snapshot	O
script	O
takes	O
a	O
snapshot	O
of	O
the	O
information	O
system	O
and	O
uses	O
the	O
Django	B-Language
framework	I-Language
to	O
store	O
the	O
information	O
.	O
</s>
<s>
In	O
addition	O
,	O
certain	O
attributes	O
are	O
extracted	O
from	O
the	O
snapshot	O
and	O
stored	O
in	O
rrd	O
databases	O
using	O
the	O
gstat-update-rrd	O
script	O
.	O
</s>
<s>
Nagios	B-Application
is	O
an	O
open	O
source	O
monitoring	O
framework	O
and	O
is	O
used	O
in	O
GStat	B-Operating_System
to	O
both	O
monitor	O
the	O
information	O
system	O
components	O
and	O
validate	O
the	O
information	O
content	O
via	O
the	O
use	O
of	O
custom	O
probes	O
.	O
</s>
<s>
These	O
monitoring	O
probes	O
can	O
be	O
re-used	O
by	O
other	O
Nagios	B-Application
based	O
monitoring	O
tools	O
and	O
also	O
executed	O
on	O
the	O
command	O
line	O
,	O
which	O
enables	O
them	O
to	O
be	O
easily	O
incorporated	O
in	O
other	O
test	O
suites	O
.	O
</s>
<s>
Django	B-Language
is	O
also	O
leveraged	O
for	O
the	O
visualization	O
aspects	O
of	O
GStat	B-Operating_System
.	O
</s>
