<s>
IPOP	B-Application
(	O
IP-Over-P2P	O
)	O
is	O
an	O
open-source	B-Application
user-centric	O
software	O
virtual	O
network	O
allowing	O
end	O
users	O
to	O
define	O
and	O
create	O
their	O
own	O
virtual	B-Application
private	I-Application
networks	I-Application
(	O
VPNs	B-Application
)	O
.	O
</s>
<s>
IPOP	B-Application
virtual	O
networks	O
provide	O
end-to-end	O
tunneling	O
of	O
IP	O
or	O
Ethernet	O
over	O
“	O
TinCan	O
”	O
links	O
setup	O
and	O
managed	O
through	O
a	O
control	O
API	B-Application
to	O
create	O
various	O
software-defined	O
VPN	B-Application
overlays	O
.	O
</s>
<s>
IPOP	B-Application
started	O
as	O
a	O
research	O
project	O
at	O
the	O
University	O
of	O
Florida	O
in	O
2006	O
.	O
</s>
<s>
In	O
its	O
first-generation	O
design	O
and	O
implementation	O
,	O
IPOP	B-Application
was	O
built	O
atop	O
structured	O
P2P	O
links	O
managed	O
by	O
the	O
C#	B-Application
library	O
.	O
</s>
<s>
In	O
its	O
first	O
design	O
,	O
IPOP	B-Application
relied	O
on	O
’	O
s	O
structured	O
P2P	O
overlay	O
network	O
for	O
peer-to-peer	O
messaging	O
,	O
notifications	O
,	O
NAT	B-Protocol
traversal	I-Protocol
,	O
and	O
IP	O
tunneling	O
.	O
</s>
<s>
The	O
-based	O
IPOP	B-Application
is	O
still	O
available	O
as	O
open-source	B-Application
code	O
;	O
however	O
,	O
IPOP	B-Application
’s	O
architecture	O
and	O
implementation	O
have	O
evolved	O
.	O
</s>
<s>
Starting	O
September	O
2013	O
,	O
the	O
project	O
has	O
been	O
funded	O
by	O
the	O
National	O
Science	O
Foundation	O
under	O
the	O
SI2	O
(	O
Software	O
Infrastructure	O
for	O
Sustained	O
Innovation	O
)	O
program	O
to	O
enable	O
it	O
as	O
open-source	B-Application
“	O
scientific	O
software	O
element	O
”	O
for	O
research	O
in	O
cloud	O
computing	O
.	O
</s>
<s>
The	O
second-generation	O
design	O
of	O
IPOP	B-Application
incorporates	O
standards	O
(	O
XMPP	O
,	O
STUN	O
,	O
TURN	O
)	O
and	O
libraries	O
(	O
libjingle	B-Protocol
)	O
that	O
have	O
evolved	O
since	O
the	O
project	O
’s	O
beginning	O
to	O
create	O
P2P	O
tunnels	O
–	O
which	O
we	O
refer	O
to	O
as	O
TinCan	O
links	O
.	O
</s>
<s>
The	O
current	O
TinCan-based	O
IPOP	B-Application
implementation	O
is	O
based	O
on	O
modules	O
written	O
in	O
C/C	O
++	O
that	O
leverage	O
libjingle	B-Protocol
to	O
create	O
TinCan	O
links	O
,	O
and	O
exposing	O
a	O
set	O
of	O
APIs	B-Application
to	O
controller	O
modules	O
that	O
manage	O
the	O
setup	O
,	O
creation	O
and	O
management	O
of	O
TinCan	O
links	O
.	O
</s>
<s>
For	O
enhanced	O
modularity	O
,	O
the	O
controller	O
module	O
runs	O
as	O
a	O
separate	O
process	O
from	O
the	O
C/C	O
++	O
module	O
that	O
implements	O
TinCan	O
links	O
and	O
communicate	O
through	O
a	O
JSON-based	O
RPC	O
system	O
;	O
thus	O
the	O
controller	O
can	O
be	O
written	O
in	O
other	O
languages	O
such	O
as	O
Python	B-Language
.	O
</s>
