<s>
The	O
ARDA	O
Metadata	O
Grid	B-Architecture
Application	O
(	O
AMGA	O
)	O
is	O
a	O
general	O
purpose	O
metadata	O
catalogue	O
and	O
part	O
of	O
the	O
European	B-Operating_System
Middleware	I-Operating_System
Initiative	I-Operating_System
middleware	B-General_Concept
distribution	O
.	O
</s>
<s>
It	O
was	O
originally	O
developed	O
by	O
the	O
EGEE	O
project	O
as	O
part	O
of	O
its	O
gLite	B-Operating_System
middleware	B-General_Concept
,	O
when	O
it	O
became	O
clear	O
that	O
many	O
Grid	B-Architecture
applications	O
needed	O
metadata	O
information	O
on	O
files	O
and	O
to	O
organize	O
a	O
work-flow	O
.	O
</s>
<s>
AMGA	O
is	O
now	O
developed	O
and	O
supported	O
by	O
the	O
European	B-Operating_System
Middleware	I-Operating_System
Initiative	I-Operating_System
.	O
</s>
<s>
AMGA	O
as	O
a	O
metadata	O
service	O
allows	O
users	O
to	O
attach	O
metadata	O
information	O
to	O
files	O
stored	O
on	O
the	O
Grid	B-Architecture
,	O
where	O
metadata	O
can	O
be	O
any	O
relationally	O
organized	O
data	O
typically	O
stored	O
in	O
a	O
relational	O
database	O
system	O
(	O
RDBMS	O
)	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
metadata	O
in	O
AMGA	O
can	O
also	O
be	O
stored	O
independently	O
of	O
any	O
associated	O
files	O
,	O
which	O
allows	O
AMGA	O
to	O
be	O
used	O
as	O
a	O
general	O
access	O
tool	O
to	O
relational	O
databases	O
on	O
the	O
Grid	B-Architecture
.	O
</s>
<s>
AMGA	O
features	O
a	O
simple	O
to	O
learn	O
metadata	O
access	O
language	O
,	O
which	O
has	O
been	O
very	O
useful	O
for	O
the	O
adoption	O
of	O
AMGA	O
in	O
smaller	O
Grid	B-Architecture
applications	O
,	O
as	O
it	O
considerably	O
lowers	O
the	O
technical	O
hurdle	O
to	O
make	O
use	O
of	O
relational	O
data	O
.	O
</s>
<s>
By	O
the	O
Health-e-child	O
project	O
)	O
,	O
but	O
also	O
to	O
increase	O
the	O
scalability	O
and	O
improve	O
the	O
access	O
times	O
on	O
a	O
globally	O
deployed	O
Grid	B-Architecture
(	O
as	O
done	O
by	O
the	O
Wisdom	O
project	O
)	O
.	O
</s>
<s>
Security	O
on	O
the	O
Grid	B-Architecture
is	O
a	O
major	O
concern	O
,	O
and	O
AMGA	O
features	O
different	O
authentication	O
methods	O
via	O
(	O
Grid-Proxy	O
-	O
)	O
Certificates	O
as	O
well	O
as	O
very	O
flexible	O
accesses	O
control	O
mechanisms	O
for	O
individual	O
data	O
items	O
based	O
on	O
ACLs	O
.	O
</s>
<s>
In	O
particular	O
these	O
security	O
features	O
have	O
made	O
AMGA	O
the	O
de	O
facto	O
standard	O
for	O
metadata	O
and	O
relational	O
database	O
access	O
on	O
the	O
Grid	B-Architecture
for	O
biomedical	O
applications	O
.	O
</s>
