<s>
A	O
gateway	B-Application
is	O
a	O
piece	O
of	O
networking	B-Device
hardware	I-Device
or	O
software	O
used	O
in	O
telecommunications	O
networks	O
that	O
allows	O
data	O
to	O
flow	O
from	O
one	O
discrete	O
network	O
to	O
another	O
.	O
</s>
<s>
Gateways	B-Application
are	O
distinct	O
from	O
routers	B-Protocol
or	O
switches	B-Protocol
in	O
that	O
they	O
communicate	O
using	O
more	O
than	O
one	O
protocol	O
to	O
connect	O
multiple	O
networks	O
and	O
can	O
operate	O
at	O
any	O
of	O
the	O
seven	O
layers	O
of	O
the	O
open	O
systems	O
interconnection	O
model	O
(	O
OSI	O
)	O
.	O
</s>
<s>
The	O
term	O
gateway	B-Application
can	O
also	O
loosely	O
refer	O
to	O
a	O
computer	O
or	O
computer	O
program	O
configured	O
to	O
perform	O
the	O
tasks	O
of	O
a	O
gateway	B-Application
,	O
such	O
as	O
a	O
default	B-Protocol
gateway	I-Protocol
or	O
router	B-Protocol
,	O
and	O
in	O
the	O
case	O
of	O
HTTP	B-Protocol
,	O
gateway	B-Application
is	O
also	O
often	O
used	O
as	O
a	O
synonym	O
for	O
reverse	B-General_Concept
proxy	I-General_Concept
.	O
</s>
<s>
A	O
network	B-Application
gateway	I-Application
provides	O
a	O
connection	O
between	O
networks	O
and	O
contains	O
devices	O
,	O
such	O
as	O
protocol	O
translators	O
,	O
impedance	O
matchers	O
,	O
rate	O
converters	O
,	O
fault	B-General_Concept
isolators	O
,	O
or	O
signal	O
translators	O
.	O
</s>
<s>
A	O
network	B-Application
gateway	I-Application
requires	O
the	O
establishment	O
of	O
mutually	O
acceptable	O
administrative	O
procedures	O
between	O
the	O
networks	O
using	O
the	O
gateway	B-Application
.	O
</s>
<s>
Network	B-Application
gateways	I-Application
,	O
known	O
as	O
protocol	O
translation	O
gateways	B-Application
or	O
mapping	O
gateways	B-Application
,	O
can	O
perform	O
protocol	O
conversions	O
to	O
connect	O
networks	O
with	O
different	O
network	O
protocol	O
technologies	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
network	B-Application
gateway	I-Application
connects	O
an	O
office	O
or	O
home	O
intranet	B-General_Concept
to	O
the	O
Internet	O
.	O
</s>
<s>
If	O
an	O
office	O
or	O
home	O
computer	O
user	O
wants	O
to	O
load	O
a	O
web	O
page	O
,	O
at	O
least	O
two	O
network	B-Application
gateways	I-Application
are	O
accessed	O
—	O
one	O
to	O
get	O
from	O
the	O
office	O
or	O
home	O
network	O
to	O
the	O
Internet	O
and	O
one	O
to	O
get	O
from	O
the	O
Internet	O
to	O
the	O
computer	O
that	O
serves	O
the	O
web	O
page	O
.	O
</s>
<s>
On	O
an	O
Internet	B-Protocol
Protocol	I-Protocol
(	O
IP	O
)	O
network	O
,	O
IP	O
packets	O
with	O
a	O
destination	O
outside	O
a	O
given	O
subnet	B-Protocol
mask	I-Protocol
are	O
sent	O
to	O
the	O
network	B-Application
gateway	I-Application
.	O
</s>
<s>
is	O
sent	O
to	O
the	O
network	B-Application
gateway	I-Application
.	O
</s>
<s>
IPv6	B-Protocol
networks	O
work	O
in	O
a	O
similar	O
way	O
.	O
</s>
<s>
While	O
forwarding	O
an	O
IP	O
packet	O
to	O
another	O
network	O
,	O
the	O
gateway	B-Application
may	O
perform	O
network	B-Protocol
address	I-Protocol
translation	I-Protocol
.	O
</s>
<s>
In	O
enterprise	B-General_Concept
networks	I-General_Concept
,	O
a	O
network	B-Application
gateway	I-Application
usually	O
also	O
acts	O
as	O
a	O
proxy	B-Application
server	I-Application
and	O
a	O
firewall	B-Application
.	O
</s>
<s>
On	O
Microsoft	O
Windows	O
,	O
the	O
Internet	B-Protocol
Connection	I-Protocol
Sharing	I-Protocol
feature	O
allows	O
a	O
computer	O
to	O
act	O
as	O
a	O
gateway	B-Application
by	O
offering	O
a	O
connection	O
between	O
the	O
Internet	O
and	O
an	O
internal	B-General_Concept
network	I-General_Concept
.	O
</s>
<s>
An	O
Internet-to-orbit	O
gateway	B-Application
(	O
I2O	O
)	O
connects	O
computers	O
or	O
devices	O
on	O
the	O
Internet	O
to	O
computer	O
systems	O
orbiting	O
Earth	O
,	O
such	O
as	O
satellites	O
or	O
crewed	O
spacecraft	O
.	O
</s>
<s>
Project	O
HERMES	O
,	O
run	O
by	O
the	O
Ecuadorian	O
Civilian	O
Space	O
Agency	O
,	O
was	O
first	O
to	O
implement	O
this	O
kind	O
of	O
gateway	B-Application
on	O
June	O
6	O
,	O
2009	O
.	O
</s>
<s>
The	O
Global	O
Educational	O
Network	O
for	O
Satellite	O
Operations	O
(	O
GENSO	O
)	O
is	O
another	O
type	O
of	O
I2O	O
gateway	B-Application
.	O
</s>
<s>
A	O
cloud	O
storage	O
gateway	B-Application
is	O
a	O
network	O
appliance	O
or	O
server	B-Application
which	O
translates	O
cloud	O
storage	O
APIs	B-Application
such	O
as	O
SOAP	B-Application
or	O
REST	B-Protocol
to	O
block-based	O
storage	O
protocols	O
such	O
as	O
iSCSI	B-Protocol
,	O
Fiber	B-Architecture
Channel	I-Architecture
or	O
file-based	O
interfaces	O
such	O
as	O
NFS	B-Protocol
or	O
CIFS	B-Operating_System
.	O
</s>
<s>
Cloud	O
storage	O
gateways	B-Application
enable	O
companies	O
to	O
integrate	O
private	O
cloud	O
storage	O
into	O
applications	O
without	O
moving	O
the	O
applications	O
into	O
a	O
public	O
cloud	O
,	O
thereby	O
simplifying	O
data	O
protection	O
.	O
</s>
<s>
An	B-Operating_System
Internet	I-Operating_System
of	I-Operating_System
things	I-Operating_System
(	O
IoT	B-Operating_System
)	O
gateway	B-Application
provides	O
the	O
bridge	O
(	O
protocol	O
converter	O
)	O
between	O
IoT	B-Operating_System
devices	O
in	O
the	O
field	O
,	O
the	O
cloud	O
,	O
and	O
user	O
equipment	O
such	O
as	O
smartphones	O
.	O
</s>
<s>
The	O
IoT	B-Operating_System
gateway	B-Application
provides	O
a	O
communication	O
link	O
between	O
the	O
field	O
and	O
the	O
cloud	O
,	O
and	O
may	O
provide	O
offline	O
services	O
and	O
real-time	O
control	O
of	O
devices	O
in	O
the	O
field	O
.	O
</s>
<s>
To	O
achieve	O
sustainable	O
interoperability	O
in	O
the	B-Operating_System
Internet	I-Operating_System
of	I-Operating_System
things	I-Operating_System
ecosystem	O
,	O
two	O
dominant	O
architectures	O
for	O
data	O
exchange	O
protocols	O
are	O
used	O
:	O
bus-based	O
(	O
DDS	B-Application
,	O
REST	B-Protocol
,	O
XMPP	B-Protocol
)	O
and	O
broker-based	O
(	O
AMQP	B-Operating_System
,	O
CoAP	B-Device
,	O
MQTT	B-Application
,	O
JMI	B-Language
)	O
.	O
</s>
<s>
Protocols	O
that	O
support	O
information	O
exchange	O
between	O
interoperable	O
domains	O
are	O
classified	O
as	O
message-centric	O
(	O
AMQP	B-Operating_System
,	O
MQTT	B-Application
,	O
JMS	B-Language
,	O
REST	B-Protocol
)	O
or	O
data-centric	O
(	O
DDS	B-Application
,	O
CoAP	B-Device
,	O
XMPP	B-Protocol
)	O
.	O
</s>
<s>
C	O
,	O
Java	O
,	O
Python	O
and	O
some	O
scripting	O
languages	O
are	O
the	O
preferred	O
choices	O
of	O
IoT	B-Operating_System
application	O
developers	O
.	O
</s>
<s>
IoT	B-Operating_System
nodes	O
use	O
separate	O
IoT	B-Operating_System
gateways	B-Application
to	O
handle	O
protocol	O
conversion	O
,	O
database	O
storage	O
or	O
decision	O
making	O
(	O
e.g.	O
</s>
