<s>
Function	B-Application
as	I-Application
a	I-Application
service	I-Application
(	O
FaaS	B-Application
)	O
is	O
a	O
category	O
of	O
cloud	O
computing	O
services	O
that	O
provides	O
a	O
platform	B-Device
allowing	O
customers	O
to	O
develop	O
,	O
run	O
,	O
and	O
manage	O
application	O
functionalities	O
without	O
the	O
complexity	O
of	O
building	O
and	O
maintaining	O
the	O
infrastructure	O
typically	O
associated	O
with	O
developing	O
and	O
launching	O
an	O
app	O
.	O
</s>
<s>
Building	O
an	O
application	O
following	O
this	O
model	O
is	O
one	O
way	O
of	O
achieving	O
a	O
"	O
serverless	B-General_Concept
"	O
architecture	O
,	O
and	O
is	O
typically	O
used	O
when	O
building	O
microservices	O
applications	O
.	O
</s>
<s>
FaaS	B-Application
was	O
initially	O
offered	O
by	O
various	O
start-ups	O
circa	O
2010	O
,	O
such	O
as	O
PiCloud	O
.	O
</s>
<s>
AWS	B-Application
Lambda	I-Application
was	O
the	O
first	O
FaaS	B-Application
offering	O
by	O
a	O
large	O
public	O
cloud	O
vendor	O
,	O
followed	O
by	O
,	O
Microsoft	B-Application
Azure	I-Application
Functions	O
,	O
IBM/Apache	O
'	O
s	O
OpenWhisk	B-General_Concept
(	O
open	B-License
source	I-License
)	O
in	O
2016	O
and	O
Oracle	B-General_Concept
Cloud	I-General_Concept
Fn	O
(	O
open	B-License
source	I-License
)	O
in	O
2017	O
.	O
</s>
<s>
Use	O
cases	O
for	O
FaaS	B-Application
are	O
associated	O
with	O
"	O
on-demand	O
"	O
functionality	O
that	O
enables	O
the	O
supporting	O
infrastructure	O
to	O
be	O
powered	O
down	O
and	O
not	O
incur	O
charges	O
when	O
not	O
in	O
use	O
.	O
</s>
<s>
Examples	O
include	O
data	O
processing	O
(	O
e.g.	O
,	O
batch	B-General_Concept
processing	I-General_Concept
,	O
stream	B-Application
processing	I-Application
,	O
extract-transform-load	O
(	O
ETL	O
)	O
)	O
,	O
Internet	B-Operating_System
of	I-Operating_System
things	I-Operating_System
(	O
IoT	B-Operating_System
)	O
services	O
for	O
Internet-connected	O
devices	O
,	O
mobile	B-Application
applications	I-Application
,	O
and	O
web	B-Application
applications	I-Application
.	O
</s>
<s>
Another	O
real-world	O
use	O
case	O
can	O
be	O
creating	O
APIs	B-General_Concept
for	O
already	O
built	O
applications	O
without	O
breaking	O
down	O
or	O
modifying	O
the	O
current	O
or	O
existing	O
functionality	O
of	O
the	O
application	O
.	O
</s>
<s>
Platform	B-Application
as	I-Application
a	I-Application
service	I-Application
(	O
PaaS	B-Application
)	O
application	O
hosting	O
services	O
is	O
similar	O
to	O
FaaS	B-Application
in	O
that	O
they	O
also	O
hide	O
"	O
servers	O
"	O
from	O
developers	O
.	O
</s>
<s>
By	O
contrast	O
,	O
FaaS	B-Application
does	O
not	O
require	O
any	O
server	O
process	O
constantly	O
being	O
run	O
.	O
</s>
<s>
While	O
an	O
initial	O
request	O
may	O
take	O
longer	O
to	O
be	O
handled	O
than	O
an	O
application	O
hosting	O
platform	B-Device
(	O
up	O
to	O
several	O
seconds	O
)	O
,	O
caching	O
may	O
enable	O
subsequent	O
requests	O
to	O
be	O
handled	O
within	O
milliseconds	O
.	O
</s>
