<s>
Nimbus	B-General_Concept
is	O
a	O
toolkit	O
that	O
,	O
once	O
installed	O
on	O
a	O
cluster	B-Architecture
,	O
provides	O
an	O
infrastructure	B-General_Concept
as	I-General_Concept
a	I-General_Concept
service	I-General_Concept
cloud	B-Architecture
to	O
its	O
client	O
via	O
WSRF-based	O
or	O
Amazon	B-General_Concept
EC2	I-General_Concept
WSDL	O
web	O
service	O
APIs	B-Application
.	O
</s>
<s>
Nimbus	B-General_Concept
is	O
free	B-License
and	I-License
open-source	I-License
software	I-License
,	O
subject	O
to	O
the	O
requirements	O
of	O
the	O
Apache	B-Application
License	I-Application
,	O
version	O
2	O
.	O
</s>
<s>
Nimbus	B-General_Concept
supports	O
both	O
the	O
hypervisors	B-Operating_System
Xen	B-Operating_System
and	O
KVM	B-Application
and	O
virtual	O
machine	O
schedulers	O
Portable	B-Application
Batch	I-Application
System	I-Application
and	O
Oracle	B-Operating_System
Grid	I-Operating_System
Engine	I-Operating_System
.	O
</s>
