<s>
Apple	B-Operating_System
Push	I-Operating_System
Notification	I-Operating_System
service	I-Operating_System
(	O
commonly	O
referred	O
to	O
as	O
Apple	O
Notification	B-General_Concept
Service	I-General_Concept
or	O
APNs	B-Operating_System
)	O
is	O
a	O
platform	O
notification	B-General_Concept
service	I-General_Concept
created	O
by	O
Apple	O
Inc	O
.	O
that	O
enables	O
third	O
party	O
application	O
developers	O
to	O
send	O
notification	O
data	O
to	O
applications	O
installed	O
on	O
Apple	O
devices	O
.	O
</s>
<s>
It	O
was	O
first	O
launched	O
with	O
iOS	B-Application
3	O
on	O
June	O
17	O
,	O
2009	O
.	O
</s>
<s>
APNs	B-Operating_System
support	O
for	O
local	O
applications	O
was	O
later	O
added	O
to	O
the	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
API	B-Application
beginning	O
with	O
the	O
release	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
10.7	I-Application
(	O
"	O
Lion	B-Application
"	O
)	O
.	O
</s>
<s>
Support	O
for	O
website	O
notifications	O
was	O
later	O
added	O
with	O
the	O
release	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.9	I-Operating_System
(	O
"	O
Mavericks	O
"	O
)	O
.	O
</s>
<s>
Apple	O
announced	O
the	O
service	O
on	O
June	O
9	O
,	O
2008	O
with	O
an	O
original	O
stated	O
release	O
for	O
that	O
September	O
;	O
however	O
,	O
as	O
stated	O
by	O
Scott	O
Forstall	O
at	O
the	O
iOS	B-Application
3.0	O
preview	O
event	O
on	O
March	O
17	O
,	O
2009	O
,	O
the	O
rollout	O
was	O
delayed	O
after	O
a	O
decision	O
to	O
restructure	O
the	O
APNs	B-Operating_System
for	O
scalability	O
purposes	O
due	O
to	O
the	O
allegedly	O
"	O
overwhelming	O
"	O
response	O
to	O
the	O
announcement	O
of	O
the	O
APNs	B-Operating_System
.	O
</s>
<s>
At	O
both	O
events	O
,	O
Forstall	O
stated	O
that	O
push	B-General_Concept
notifications	I-General_Concept
better	O
conserve	O
battery	O
than	O
background	B-Operating_System
processes	I-Operating_System
(	O
which	O
are	O
used	O
in	O
pull	O
technology	O
)	O
for	O
receiving	O
notifications	O
.	O
</s>
<s>
APNs	B-Operating_System
was	O
first	O
launched	O
together	O
with	O
iOS	B-Application
3.0	O
on	O
June	O
17	O
,	O
2009	O
.	O
</s>
<s>
The	O
release	O
of	O
iOS	B-Application
5.0	O
included	O
a	O
Notification	B-Operating_System
Center	I-Operating_System
,	O
adding	O
support	O
for	O
receiving	O
and	O
reading	O
local	O
notifications	O
in	O
a	O
single	O
place	O
.	O
</s>
<s>
APNs	B-Operating_System
was	O
also	O
added	O
as	O
an	O
API	B-Application
to	O
Mac	B-Application
OS	I-Application
X	I-Application
10.7	I-Application
(	O
"	O
Lion	B-Application
"	O
)	O
so	O
that	O
developers	O
could	O
begin	O
updating	O
their	O
third-party	O
applications	O
and	O
start	O
utilizing	O
the	O
service	O
.	O
</s>
<s>
Support	O
was	O
later	O
improved	O
in	O
OS	B-Operating_System
X	I-Operating_System
10.8	I-Operating_System
(	O
"	O
Mountain	O
Lion	B-Application
"	O
)	O
with	O
the	O
introduction	O
of	O
a	O
Notification	B-Operating_System
Center	I-Operating_System
.	O
</s>
<s>
As	O
with	O
iOS	B-Application
5.0	O
,	O
the	O
improvement	O
allowed	O
users	O
to	O
manage	O
and	O
read	O
their	O
received	O
notifications	O
in	O
a	O
single	O
location	O
.	O
</s>
<s>
The	O
release	O
of	O
OS	B-Operating_System
X	I-Operating_System
10.9	I-Operating_System
(	O
"	O
Mavericks	O
"	O
)	O
included	O
Safari	B-Application
7.0	O
,	O
which	O
added	O
support	O
for	O
accepting	O
and	O
receiving	O
APNs	B-Operating_System
notifications	O
from	O
websites	O
that	O
the	O
user	O
granted	O
permission	O
to	O
.	O
</s>
<s>
In	O
December	O
2015	O
,	O
a	O
new	O
HTTP/2	B-Protocol
provider	O
API	B-Application
was	O
released	O
by	O
Apple	O
,	O
effectively	O
replacing	O
the	O
now-legacy	O
binary	O
interface	O
.	O
</s>
<s>
The	O
maximum	O
notification	O
payload	O
size	O
allowed	O
using	O
the	O
HTTP/2	B-Protocol
API	B-Application
is	O
4	O
kilobytes	O
.	O
</s>
<s>
Apple	O
shut	O
down	O
the	O
legacy	O
binary	O
API	B-Application
at	O
the	O
end	O
of	O
March	O
2021	O
.	O
</s>
<s>
The	O
HTTP/2	B-Protocol
provider	O
for	O
APNs	B-Operating_System
uses	O
TCP	O
port	O
443	O
as	O
the	O
main	O
port	O
of	O
communication	O
,	O
but	O
developers	O
are	O
also	O
allowed	O
to	O
use	O
TCP	O
port	O
2197	O
if	O
outbound	O
access	O
to	O
port	O
443	O
is	O
blocked	O
by	O
firewalls	O
.	O
</s>
