<s>
Google	B-Application
App	I-Application
Engine	I-Application
(	O
often	O
referred	O
to	O
as	O
GAE	O
or	O
simply	O
App	B-Application
Engine	I-Application
)	O
is	O
a	O
cloud	B-Architecture
computing	I-Architecture
platform	I-Architecture
as	O
a	O
service	O
for	O
developing	O
and	O
hosting	O
web	B-Application
applications	I-Application
in	O
Google-managed	O
data	B-Operating_System
centers	I-Operating_System
.	O
</s>
<s>
App	B-Application
Engine	I-Application
offers	O
automatic	O
scaling	O
for	O
web	B-Application
applications	I-Application
—	O
as	O
the	O
number	O
of	O
requests	O
increases	O
for	O
an	O
application	O
,	O
App	B-Application
Engine	I-Application
automatically	O
allocates	O
more	O
resources	O
for	O
the	O
web	B-Application
application	I-Application
to	O
handle	O
the	O
additional	O
demand	O
.	O
</s>
<s>
Google	B-Application
App	I-Application
Engine	I-Application
primarily	O
supports	O
Go	B-Application
,	O
PHP	B-Application
,	O
Java	B-Language
,	O
Python	B-Language
,	O
Node.js	B-Language
,	O
.NET	B-Application
,	O
and	O
Ruby	B-Language
applications	O
,	O
although	O
it	O
can	O
also	O
support	O
other	O
languages	O
via	O
"	O
custom	O
runtimes	O
"	O
.	O
</s>
<s>
Google	B-Application
App	I-Application
Engine	I-Application
primarily	O
supports	O
Go	B-Application
,	O
PHP	B-Application
,	O
Java	B-Language
,	O
Python	B-Language
,	O
Node.js	B-Language
,	O
.NET	B-Application
,	O
and	O
Ruby	B-Language
applications	O
,	O
although	O
it	O
can	O
also	O
support	O
other	O
languages	O
via	O
"	O
custom	O
runtimes	O
"	O
.	O
</s>
<s>
Python	B-Language
web	O
frameworks	O
that	O
run	O
on	O
Google	B-Application
App	I-Application
Engine	I-Application
include	O
Django	B-Language
,	O
CherryPy	B-Application
,	O
Pyramid	O
,	O
Flask	B-Language
,	O
web2py	B-Application
and	O
webapp2	O
,	O
as	O
well	O
as	O
a	O
custom	O
Google-written	O
webapp	B-Application
framework	O
and	O
several	O
others	O
designed	O
specifically	O
for	O
the	O
platform	O
that	O
emerged	O
since	O
the	O
release	O
.	O
</s>
<s>
Any	O
Python	B-Language
framework	O
that	O
supports	O
the	O
WSGI	B-Language
using	O
the	O
CGI	O
adapter	O
can	O
be	O
used	O
to	O
create	O
an	O
application	O
;	O
the	O
framework	O
can	O
be	O
uploaded	O
with	O
the	O
developed	O
application	O
.	O
</s>
<s>
Third-party	O
libraries	O
written	O
in	O
pure	O
Python	B-Language
may	O
also	O
be	O
uploaded	O
.	O
</s>
<s>
Google	B-Application
App	I-Application
Engine	I-Application
supports	O
many	O
Java	B-Language
standards	O
and	O
frameworks	O
.	O
</s>
<s>
Core	O
to	O
this	O
is	O
the	O
servlet	B-Application
2.5	I-Application
technology	I-Application
using	O
the	O
open-source	O
Jetty	B-Language
Web	I-Language
Server	I-Language
,	O
along	O
with	O
accompanying	O
technologies	O
such	O
as	O
JSP	B-Language
.	O
</s>
<s>
JavaServer	B-Language
Faces	I-Language
operates	O
with	O
some	O
workarounds	O
.	O
</s>
<s>
A	O
newer	O
release	O
of	O
App	B-Application
Engine	I-Application
Standard	O
Java	B-Language
in	O
Beta	O
supports	O
Java8	O
,	O
Servlet	B-Application
3.1	O
and	O
Jetty9	O
.	O
</s>
<s>
Though	O
the	O
integrated	O
database	O
,	O
Google	B-Application
Cloud	O
Datastore	O
,	O
may	O
be	O
unfamiliar	O
to	O
programmers	O
,	O
it	O
is	O
accessed	O
and	O
supported	O
with	O
JPA	B-Language
,	O
JDO	B-Language
,	O
and	O
by	O
the	O
simple	O
low-level	O
API	O
.	O
</s>
<s>
There	O
are	O
several	O
alternative	O
libraries	O
and	O
frameworks	O
you	O
can	O
use	O
to	O
model	O
and	O
map	O
the	O
data	O
to	O
the	O
database	O
such	O
as	O
Objectify	O
,	O
Slim3	O
and	O
Jello	B-Language
framework	I-Language
.	O
</s>
<s>
The	B-Application
Spring	I-Application
Framework	I-Application
works	O
with	O
GAE	O
.	O
</s>
<s>
Apache	B-Language
Struts	I-Language
1	O
is	O
supported	O
,	O
and	O
Struts	B-Language
2	I-Language
runs	O
with	O
workarounds	O
.	O
</s>
<s>
The	O
Django	B-Language
web	I-Language
framework	I-Language
and	O
applications	O
running	O
on	O
it	O
can	O
be	O
used	O
on	O
App	B-Application
Engine	I-Application
with	O
modification	O
.	O
</s>
<s>
Django-nonrel	O
aims	O
to	O
allow	O
Django	B-Language
to	O
work	O
with	O
non-relational	O
databases	O
and	O
the	O
project	O
includes	O
support	O
for	O
App	B-Application
Engine	I-Application
.	O
</s>
<s>
All	O
billed	O
App	B-Application
Engine	I-Application
applications	O
have	O
a	O
99.95	O
%	O
uptime	O
SLA	O
.	O
</s>
<s>
App	B-Application
Engine	I-Application
is	O
designed	O
in	O
such	O
a	O
way	O
that	O
it	O
can	O
sustain	O
multiple	O
datacenter	B-Operating_System
outages	O
without	O
any	O
downtime	O
.	O
</s>
<s>
Paid	O
support	O
from	O
Google	B-Application
engineers	O
is	O
offered	O
as	O
part	O
of	O
Premier	O
Accounts	O
.	O
</s>
<s>
SDK	O
version	O
1.2.2	O
adds	O
support	O
for	O
bulk	O
downloads	O
of	O
data	O
using	O
Python	B-Language
.	O
</s>
<s>
The	O
open	O
source	O
Python	B-Language
projects	O
gaebar	O
,	O
approcket	O
,	O
and	O
gawsh	O
also	O
allow	O
users	O
to	O
download	O
and	O
back	O
up	O
App	B-Application
Engine	I-Application
data	O
.	O
</s>
<s>
No	O
method	O
for	O
bulk	O
downloading	O
data	O
from	O
GAE	O
using	O
Java	B-Language
currently	O
exists	O
.	O
</s>
<s>
Developers	O
have	O
read	O
only	O
access	O
to	O
the	O
filesystem	O
on	O
App	B-Application
Engine	I-Application
.	O
</s>
<s>
App	B-Application
Engine	I-Application
can	O
only	O
execute	O
code	O
called	O
from	O
an	O
HTTP	O
request	O
(	O
scheduled	O
background	O
tasks	O
allow	O
for	O
self	O
calling	O
HTTP	O
requests	O
)	O
.	O
</s>
<s>
Users	O
may	O
upload	O
arbitrary	O
Python	B-Language
modules	O
,	O
but	O
only	O
if	O
they	O
are	O
pure-Python	O
;	O
C	B-Language
and	O
Pyrex	B-Application
modules	O
are	O
not	O
supported	O
.	O
</s>
<s>
Java	B-Language
applications	O
may	O
only	O
use	O
a	O
subset	O
(	O
The	O
JRE	O
Class	O
White	O
List	O
)	O
of	O
the	O
classes	O
from	O
the	O
JRE	O
standard	O
edition	O
.	O
</s>
<s>
This	O
restriction	O
does	O
not	O
exist	O
with	O
the	O
App	B-Application
Engine	I-Application
Standard	O
Java8	O
runtime	O
.	O
</s>
<s>
Compared	O
to	O
other	O
scalable	O
hosting	O
services	O
such	O
as	O
Amazon	B-General_Concept
EC2	I-General_Concept
,	O
App	B-Application
Engine	I-Application
provides	O
more	O
infrastructure	O
to	O
make	O
it	O
easy	O
to	O
write	O
scalable	O
applications	O
,	O
but	O
can	O
only	O
run	O
a	O
limited	O
range	O
of	O
applications	O
designed	O
for	O
that	O
infrastructure	O
.	O
</s>
<s>
App	B-Application
Engine	I-Application
's	O
infrastructure	O
removes	O
many	O
of	O
the	O
system	O
administration	O
and	O
development	O
challenges	O
of	O
building	O
applications	O
to	O
scale	O
to	O
hundreds	O
of	O
requests	O
per	O
second	O
and	O
beyond	O
.	O
</s>
<s>
Google	B-Application
handles	O
deploying	O
code	O
to	O
a	O
cluster	O
,	O
monitoring	O
,	O
failover	O
,	O
and	O
launching	O
application	O
instances	O
as	O
necessary	O
.	O
</s>
<s>
While	O
other	O
services	O
let	O
users	O
install	O
and	O
configure	O
nearly	O
any	O
*	O
NIX	O
compatible	O
software	O
,	O
App	B-Application
Engine	I-Application
requires	O
developers	O
to	O
use	O
only	O
its	O
supported	O
languages	O
,	O
APIs	O
,	O
and	O
frameworks	O
.	O
</s>
<s>
Current	O
APIs	O
allow	O
storing	O
and	O
retrieving	O
data	O
from	O
the	O
document-oriented	O
Google	B-Application
Cloud	O
Datastore	O
database	O
;	O
making	O
HTTP	O
requests	O
;	O
sending	O
e-mail	O
;	O
manipulating	O
images	O
;	O
and	O
caching	O
.	O
</s>
<s>
Google	B-Application
Cloud	O
SQL	B-Language
can	O
be	O
used	O
for	O
App	B-Application
Engine	I-Application
applications	O
requiring	O
a	O
relational	O
MySQL	B-Application
compatible	O
database	O
backend	O
.	O
</s>
<s>
Google	B-Application
App	I-Application
Engine	I-Application
's	O
integrated	O
Google	B-Application
Cloud	O
Datastore	O
database	O
has	O
a	O
SQL-like	O
syntax	O
called	O
"	O
GQL	O
"	O
(	O
Google	B-Application
Query	B-Language
Language	O
)	O
.	O
</s>
<s>
GQL	O
does	O
not	O
support	O
the	O
Join	B-Language
statement	I-Language
.	O
</s>
<s>
is	O
the	O
successor	O
to	O
Google	B-Application
Cloud	O
Datastore	O
and	O
replaces	O
GQL	O
with	O
a	O
document-based	O
query	B-Language
method	O
that	O
treats	O
stored	O
objects	O
as	O
.	O
</s>
<s>
Developers	O
worry	O
that	O
the	O
applications	O
will	O
not	O
be	O
portable	O
from	O
App	B-Application
Engine	I-Application
and	O
fear	O
being	O
locked	O
into	O
the	O
technology	O
.	O
</s>
<s>
In	O
response	O
,	O
there	O
are	O
a	O
number	O
of	O
projects	O
to	O
create	O
open-source	O
back-ends	O
for	O
the	O
various	O
proprietary/closed	O
APIs	O
of	O
app	B-Application
engine	I-Application
,	O
especially	O
the	O
datastore	O
.	O
</s>
<s>
AppScale	B-Application
,	O
CapeDwarf	O
and	O
TyphoonAE	O
are	O
a	O
few	O
of	O
the	O
open	O
source	O
efforts	O
.	O
</s>
<s>
AppScale	B-Application
automatically	O
deploys	O
and	O
scales	O
unmodified	O
Google	B-Application
App	I-Application
Engine	I-Application
applications	O
over	O
popular	O
public	O
and	O
private	O
cloud	O
systems	O
and	O
on-premises	O
clusters	O
.	O
</s>
<s>
AppScale	B-Application
can	O
run	O
Python	B-Language
,	O
Java	B-Language
,	O
PHP	B-Application
,	O
and	O
Go	B-Application
applications	O
on	O
EC2	O
,	O
Google	B-Application
Compute	O
Engine	O
,	O
Softlayer	O
,	O
Azure	O
and	O
other	O
cloud	B-Architecture
vendors	I-Architecture
.	O
</s>
<s>
TyphoonAE	O
can	O
run	O
Python	B-Language
App	B-Application
Engine	I-Application
applications	O
on	O
any	O
cloud	O
that	O
support	O
linux	O
machines	O
.	O
</s>
<s>
Web2py	B-Application
web	O
framework	O
offers	O
migration	O
between	O
SQL	B-Language
Databases	I-Language
and	O
Google	B-Application
App	I-Application
Engine	I-Application
,	O
however	O
it	O
does	O
n't	O
support	O
several	O
App	O
Engine-specific	O
features	O
such	O
as	O
transactions	O
and	O
namespaces	O
.	O
</s>
<s>
Kubernetes	B-General_Concept
is	O
an	O
open-source	O
job	O
control	O
system	O
invented	O
by	O
Google	B-Application
to	O
abstract	O
away	O
the	O
infrastructure	O
so	O
that	O
open-source	O
(	O
e.g.	O
</s>
<s>
Docker	O
)	O
containerized	O
applications	O
can	O
run	O
on	O
many	O
types	O
of	O
infrastructure	O
,	O
such	O
as	O
Amazon	B-Application
Web	I-Application
Services	I-Application
,	O
Microsoft	B-Application
Azure	I-Application
,	O
and	O
others	O
.	O
</s>
<s>
This	O
is	O
one	O
of	O
Google	B-Application
's	I-Application
answers	O
to	O
the	O
portability	O
concern	O
.	O
</s>
<s>
In	O
Google	B-Application
I/O	I-Application
2011	O
,	O
Google	B-Application
announced	O
App	B-Application
Engine	I-Application
Backends	O
,	O
which	O
are	O
allowed	O
to	O
run	O
continuously	O
,	O
and	O
consume	O
more	O
memory	O
.	O
</s>
<s>
In	O
Oct	O
2011	O
,	O
Google	B-Application
previewed	O
a	O
zero	O
maintenance	O
SQL	B-Language
database	I-Language
,	O
which	O
supports	O
JDBC	O
and	O
DB-API	O
.	O
</s>
<s>
This	O
service	O
allows	O
creating	O
,	O
configuring	O
,	O
and	O
using	O
relational	O
databases	O
with	O
App	B-Application
Engine	I-Application
applications	O
.	O
</s>
<s>
Google	B-Application
Cloud	O
SQL	B-Language
supports	O
MySQL	B-Application
8.0	O
,	O
5.7	O
and	O
5.6	O
.	O
</s>
<s>
Google	B-Application
App	I-Application
Engine	I-Application
requires	O
a	O
Google	B-Application
account	O
to	O
get	O
started	O
,	O
and	O
an	O
account	O
may	O
allow	O
the	O
developer	O
to	O
register	O
up	O
to	O
25	O
free	O
applications	O
and	O
an	O
unlimited	O
number	O
of	O
paid	O
applications	O
.	O
</s>
<s>
Google	B-Application
App	I-Application
Engine	I-Application
defines	O
usage	O
quotas	O
for	O
free	O
applications	O
.	O
</s>
