<s>
Web2py	B-Application
is	O
an	O
open-source	B-Application
web	B-Application
application	I-Application
framework	I-Application
written	O
in	O
the	O
Python	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
Web2py	B-Application
allows	O
web	B-Operating_System
developers	I-Operating_System
to	O
program	O
dynamic	O
web	O
content	O
using	O
Python	B-Language
.	O
</s>
<s>
Web2py	B-Application
is	O
designed	O
to	O
help	O
reduce	O
tedious	O
web	O
development	O
tasks	O
,	O
such	O
as	O
developing	O
web	B-General_Concept
forms	I-General_Concept
from	O
scratch	O
,	O
although	O
a	O
web	B-Operating_System
developer	I-Operating_System
may	O
build	O
a	O
form	B-General_Concept
from	O
scratch	O
if	O
required	O
.	O
</s>
<s>
Web2py	B-Application
was	O
originally	O
designed	O
as	O
a	O
teaching	O
tool	O
with	O
emphasis	O
on	O
ease	O
of	O
use	O
and	O
deployment	B-Application
.	O
</s>
<s>
The	O
design	O
of	O
web2py	B-Application
was	O
inspired	O
by	O
the	O
Ruby	B-Application
on	I-Application
Rails	I-Application
and	O
Django	B-Language
frameworks	I-Language
.	O
</s>
<s>
Like	O
these	O
frameworks	O
,	O
web2py	B-Application
focuses	O
on	O
rapid	O
development	O
,	O
favors	O
convention	B-Application
over	I-Application
configuration	I-Application
approach	O
and	O
follows	O
a	O
model	O
–	O
view	O
–	O
controller	O
(	O
MVC	O
)	O
architectural	O
pattern	O
.	O
</s>
<s>
Web2py	B-Application
is	O
a	O
full-stack	O
framework	O
in	O
that	O
it	O
has	O
built-in	O
components	B-Architecture
for	O
all	O
major	O
functions	O
,	O
including	O
:	O
</s>
<s>
HTTP	B-Protocol
requests	I-Protocol
,	O
HTTP	B-Protocol
responses	O
,	O
cookies	B-Application
,	O
sessions	B-Protocol
;	O
</s>
<s>
multiple	O
protocols	O
HTML/XML	O
,	O
REST	B-Protocol
,	O
ATOM	B-Application
and	O
RSS	O
,	O
RTF	O
and	O
CSV	O
,	O
JSON	B-General_Concept
,	O
JSON-RPC	B-General_Concept
and	O
XML-RPC	B-Protocol
,	O
AMF-RPC	B-Protocol
(	O
Flash/Flex	O
)	O
,	O
and	O
SOAP	B-Application
;	O
</s>
<s>
CRUD	B-General_Concept
API	B-General_Concept
;	O
</s>
<s>
database	B-Application
abstraction	I-Application
layer	I-Application
(	O
DAL	B-Application
)	O
that	O
dynamically	O
generates	O
SQL	B-Language
and	O
runs	O
on	O
multiple	O
compatible	O
database	O
backends	O
;	O
</s>
<s>
RAM	B-Architecture
,	O
disk	B-Device
,	O
and	O
memcached-based	O
caching	B-General_Concept
for	O
scalability	B-Architecture
;	O
</s>
<s>
internationalization	B-General_Concept
support	O
;	O
</s>
<s>
jQuery	B-Language
for	O
Ajax	B-General_Concept
and	O
UI	B-Application
effects	O
;	O
</s>
<s>
self-submission	O
of	O
web	B-General_Concept
forms	I-General_Concept
;	O
</s>
<s>
server-side	B-Application
sessions	B-Protocol
;	O
</s>
<s>
Web2py	B-Application
uses	O
the	O
WSGI	B-Language
protocol	O
,	O
the	O
Python-oriented	O
protocol	O
for	O
communication	O
between	O
web	B-Application
server	I-Application
and	O
web	O
applications	O
.	O
</s>
<s>
It	O
also	O
provides	O
handlers	O
for	O
CGI	B-Language
and	O
the	O
FastCGI	O
protocols	O
,	O
and	O
it	O
includes	O
the	O
multi-threaded	B-Operating_System
,	O
SSL-enabled	O
Rocket	O
wsgiserver	O
.	O
</s>
<s>
All	O
development	O
,	O
debugging	O
,	O
testing	O
,	O
maintenance	O
and	O
remote	O
database	O
administration	O
can	O
(	O
optionally	O
)	O
be	O
performed	O
without	O
third-party	O
tools	O
,	O
via	O
a	O
web	O
interface	O
,	O
itself	O
a	O
web2py	B-Application
application	O
.	O
</s>
<s>
Internationalization	B-General_Concept
(	O
adding	O
languages	O
and	O
writing	O
translations	O
)	O
can	O
also	O
be	O
performed	O
from	O
this	O
IDE	B-Application
.	O
</s>
<s>
Each	O
application	O
has	O
an	O
automatically	O
generated	O
database	O
administrative	O
interface	O
,	O
similar	O
to	O
Django	B-Language
.	O
</s>
<s>
The	O
web	O
IDE	B-Application
also	O
includes	O
web-based	O
testing	O
.	O
</s>
<s>
Applications	O
can	O
also	O
be	O
created	O
from	O
the	O
command	B-Application
line	I-Application
or	O
developed	O
with	O
other	O
IDEs	O
.	O
</s>
<s>
Wing	B-Application
IDE	I-Application
allows	O
graphical	O
debugging	O
of	O
web2py	B-Application
applications	O
as	O
you	O
interact	O
with	O
it	O
from	O
your	O
web	O
browser	O
,	O
you	O
can	O
inspect	O
and	O
modify	O
variables	O
,	O
make	O
function	O
calls	O
etc	O
.	O
</s>
<s>
Eclipse/PyDev	O
—	O
Eclipse	B-Application
with	O
the	O
Aptana	O
PyDev	B-Language
plugin	O
—	O
supports	O
web2py	B-Application
as	O
well	O
.	O
</s>
<s>
The	O
extensible	O
pdb	O
debugger	O
is	O
a	O
module	O
of	O
Python	B-Language
's	O
standard	O
library	O
.	O
</s>
<s>
With	O
the	O
platform-independent	B-Operating_System
open-source	B-Application
Winpdb	O
debugger	O
,	O
one	O
can	O
perform	O
remote	O
debugging	O
over	O
TCP/IP	B-Protocol
,	O
through	O
encrypted	O
connection	O
.	O
</s>
<s>
The	O
Hello	O
World	O
program	O
with	O
web2py	B-Application
in	O
its	O
simplest	O
form	B-General_Concept
(	O
simple	O
web	O
page	O
with	O
no	O
template	O
)	O
looks	O
like	O
:	O
</s>
<s>
Web2py	B-Application
includes	O
pure	O
Python-based	O
template	B-Application
language	I-Application
,	O
with	O
no	O
indentation	O
requirements	O
and	O
a	O
server-side	B-Application
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
(	O
DOM	B-General_Concept
)	O
.	O
</s>
<s>
The	O
template	O
system	O
works	O
without	O
web2py	B-Application
.	O
</s>
<s>
Joomla	B-Protocol
1.x	O
templates	O
can	O
be	O
converted	O
to	O
web2py	B-Application
layouts	O
.	O
</s>
<s>
Web2py	B-Application
also	O
includes	O
two	O
markup	O
libraries	O
:	O
the	O
markdown2	O
text-to-HTML	O
filter	O
,	O
which	O
converts	O
Markdown	O
markup	O
to	O
HTML	B-Language
on	O
the	O
fly	O
;	O
and	O
markmin	O
which	O
is	O
inspired	O
by	O
markdown	O
but	O
supports	O
tables	O
,	O
html5	O
video/audio	O
and	O
oembed	O
protocol	O
.	O
</s>
<s>
A	O
controller	O
without	O
a	O
view	O
automatically	O
uses	O
a	O
generic	O
view	O
that	O
render	O
the	O
variables	O
returned	O
by	O
the	O
controller	O
,	O
enabling	O
the	O
development	O
of	O
an	O
application	O
's	O
business	O
logic	O
before	O
writing	O
HTML	B-Language
.	O
</s>
<s>
The	O
dict( )	O
output	O
of	O
an	O
action	O
is	O
automatically	O
rendered	O
in	O
HTML	B-Language
if	O
the	O
page	O
is	O
request	O
with	O
a	O
.html	B-Language
extension	O
,	O
in	O
JSON	B-General_Concept
if	O
the	O
page	O
is	O
requested	O
with	O
a	O
.json	B-General_Concept
extension	O
,	O
in	O
XML	B-Protocol
if	O
requested	O
with	O
.xml	B-Protocol
.	O
</s>
<s>
Each	O
web2py	B-Application
application	O
comes	O
with	O
a	O
ticketing	B-Application
system	I-Application
:	O
</s>
<s>
If	O
an	O
error	O
occurs	O
,	O
it	O
is	O
logged	O
and	O
a	O
ticket	B-Application
is	O
issued	O
to	O
the	O
user	O
.	O
</s>
<s>
Cron	B-General_Concept
is	O
a	O
mechanism	O
for	O
creating	O
and	O
running	O
recurrent	O
tasks	O
in	O
background	O
.	O
</s>
<s>
It	O
looks	O
for	O
an	O
application-specific	O
crontab	B-General_Concept
file	I-General_Concept
which	O
is	O
in	O
standard	O
crontab	B-General_Concept
format	I-General_Concept
.	O
</s>
<s>
Soft	O
cron	B-General_Concept
:	O
cron	B-General_Concept
routines	O
are	O
checked	O
after	O
web	O
page	O
content	O
has	O
been	O
served	O
,	O
does	O
not	O
guarantee	O
execution	O
precision	O
.	O
</s>
<s>
For	O
unprivileged	O
Apache	B-Application
CGI/WSGI	O
installs	O
.	O
</s>
<s>
Hard	O
cron	B-General_Concept
:	O
a	O
cron	B-General_Concept
thread	B-Operating_System
gets	O
started	O
on	O
web2py	B-Application
startup	O
.	O
</s>
<s>
For	O
Windows	B-Application
and	O
Rocket/standalone	O
web2py	B-Application
installs	O
.	O
</s>
<s>
System	O
cron	B-General_Concept
:	O
cron	B-General_Concept
functions	O
get	O
force-called	O
from	O
the	O
command	B-Application
line	I-Application
,	O
usually	O
from	O
the	O
system	O
crontab	B-General_Concept
.	O
</s>
<s>
For	O
Unix/Linux	O
systems	O
and	O
places	O
where	O
the	O
cron	B-General_Concept
triggers	O
need	O
to	O
be	O
executed	O
even	O
if	O
web2py	B-Application
is	O
not	O
running	O
at	O
the	O
moment	O
;	O
also	O
good	O
for	O
CGI/WSGI	O
installs	O
if	O
you	O
have	O
access	O
to	O
the	O
system	O
crontab	B-General_Concept
.	O
</s>
<s>
Since	O
version	O
2.3	O
the	O
use	O
of	O
cron	B-General_Concept
is	O
discouraged	O
since	O
web2py	B-Application
comes	O
with	O
a	O
master/worker	O
scheduler	O
.	O
</s>
<s>
The	O
schedule	O
is	O
better	O
than	O
cron	B-General_Concept
because	O
it	O
allows	O
to	O
specify	O
more	O
parameters	O
(	O
start	O
time	O
,	O
stop	O
time	O
,	O
number	O
of	O
repetitions	O
,	O
number	O
of	O
trials	O
in	O
case	O
of	O
error	O
)	O
and	O
do	O
a	O
better	O
job	O
at	O
running	O
within	O
constant	O
resource	O
utilization	O
.	O
</s>
<s>
Web2py	B-Application
can	O
compile	O
web	O
applications	O
for	O
distribution	O
in	O
bytecode	O
compiled	O
form	B-General_Concept
,	O
without	O
source	O
code	O
.	O
</s>
<s>
Unlike	O
frameworks	O
that	O
use	O
specialized	O
template	O
languages	O
for	O
their	O
views	O
,	O
Web2py	B-Application
can	O
also	O
compile	O
the	O
view	O
code	O
into	O
bytecode	O
,	O
since	O
it	O
is	O
pure	O
Python	B-Language
code	I-Language
.	O
</s>
<s>
Web2py	B-Application
is	O
unique	O
in	O
the	O
world	O
of	O
Python	B-Language
web	B-Application
frameworks	I-Application
because	O
models	O
and	O
controllers	O
are	O
executed	O
,	O
not	O
imported	O
.	O
</s>
<s>
They	O
are	O
executed	O
in	O
a	O
single	O
global	O
environment	O
which	O
is	O
initialized	O
at	O
each	O
HTTP	B-Protocol
request	O
.	O
</s>
<s>
Another	O
pro	O
is	O
that	O
all	O
the	O
objects	O
defined	O
within	O
this	O
environment	O
are	O
cleanly	O
reset	O
at	O
each	O
HTTP	B-Protocol
request	O
and	O
never	O
shared	O
across	O
requests	O
.	O
</s>
<s>
A	O
third	O
advantage	O
is	O
that	O
web2py	B-Application
allows	O
the	O
coexistence	O
of	O
multiple	O
applications	O
under	O
the	O
same	O
instance	O
without	O
conflicts	O
even	O
if	O
they	O
use	O
different	O
versions	O
of	O
the	O
same	O
modules	O
or	O
different	O
modules	O
with	O
the	O
same	O
name	O
.	O
</s>
<s>
Naming	O
conflict	O
is	O
more	O
likely	O
to	O
occur	O
than	O
in	O
normal	O
Python	B-Language
modules	O
.	O
</s>
<s>
Some	O
standard	O
Python	B-Language
development	O
tools	O
may	O
not	O
understand	O
objects	O
defined	O
in	O
models	O
and	O
controllers	O
.	O
</s>
<s>
Nothing	O
in	O
web2py	B-Application
prevents	O
developers	O
from	O
using	O
and	O
importing	O
normal	O
Python	B-Language
modules	O
(	O
model-less	O
approach	O
)	O
and	O
for	O
this	O
purpose	O
web2py	B-Application
provides	O
a	O
thread	B-Operating_System
local	O
object	O
(	O
current	O
)	O
to	O
facilitate	O
access	O
to	O
objects	O
associated	O
to	O
the	O
current	O
request	O
.	O
</s>
<s>
the	O
ApplicationController	O
in	O
Ruby	B-Application
on	I-Application
Rails	I-Application
)	O
means	O
that	O
common	O
controller	O
functionality	O
must	O
be	O
referenced	O
repeatedly	O
across	O
all	O
controller	O
files	O
.	O
</s>
<s>
web2py	B-Application
runs	O
on	O
Windows	B-Application
,	O
Windows	B-Operating_System
CE	I-Operating_System
phones	O
,	O
Mac	B-Device
,	O
Unix/Linux	O
,	O
Google	B-Application
App	I-Application
Engine	I-Application
,	O
Amazon	B-General_Concept
EC2	I-General_Concept
,	O
and	O
almost	O
any	O
web	O
hosting	O
via	O
Python	B-Language
2.7/3.5/3.6/pypy	O
.	O
</s>
<s>
The	O
current	O
binary	O
version	O
of	O
web2py	B-Application
(	O
for	O
Windows	B-Application
or	O
Mac	B-Device
)	O
includes	O
Python	B-Language
2.7	O
,	O
but	O
the	O
source	O
version	O
can	O
be	O
run	O
on	O
2.7	O
and	O
3.5	O
+	O
.	O
</s>
<s>
Support	O
for	O
Python	B-Language
2.6	O
has	O
been	O
dropped	O
on	O
2017	O
.	O
</s>
<s>
web2py	B-Application
since	O
v1.64.0	O
runs	O
unmodified	O
on	O
Java	B-Device
with	O
Jython	B-Language
2.5	O
,	O
without	O
any	O
known	O
limitation	O
.	O
</s>
<s>
web2py	B-Application
code	O
can	O
run	O
with	O
IronPython	B-Application
on	O
.NET	B-Application
.	O
</s>
<s>
no	O
third	O
party	O
database	O
drivers	O
(	O
not	O
even	O
SQLite	B-Language
,	O
so	O
no	O
databases	O
at	O
all	O
)	O
;	O
</s>
<s>
no	O
built-in	O
web	B-Application
server	I-Application
(	O
unless	O
you	O
cripple	O
it	O
by	O
removing	O
signals	O
and	O
logging	O
)	O
.	O
</s>
<s>
The	O
web2py	B-Application
binary	O
will	O
run	O
from	O
a	O
USB	O
drive	O
or	O
a	O
portable	O
hard	B-Device
drive	I-Device
without	O
dependencies	O
,	O
like	O
Portable	O
Python	B-Language
.	O
</s>
<s>
Web2py	B-Application
can	O
service	O
requests	O
via	O
HTTP	B-Protocol
and	O
HTTPS	B-Protocol
with	O
its	O
built-in	O
Rocket	O
server	O
,	O
with	O
Apache	B-Application
,	O
Lighttpd	B-Protocol
,	O
Cherokee	B-Language
,	O
Hiawatha	B-Application
,	O
Nginx	B-Operating_System
and	O
almost	O
any	O
other	O
web	B-Application
server	I-Application
through	O
CGI	B-Language
,	O
FastCGI	O
,	O
WSGI	B-Language
,	O
mod_proxy	O
,	O
and/or	O
mod_python	O
.	O
</s>
<s>
While	O
a	O
number	O
of	O
web2py	B-Application
developers	O
use	O
text	B-Application
editors	I-Application
such	O
as	O
Vim	B-Application
,	O
Emacs	B-Application
or	O
TextMate	B-Application
Web2py	B-Application
also	O
has	O
a	O
built-in	O
web-based	O
IDE	B-Application
.	O
</s>
<s>
Eric	B-Application
with	O
built-in	O
debugger	O
.	O
</s>
<s>
The	O
database	B-Application
abstraction	I-Application
layer	I-Application
(	O
DAL	B-Application
)	O
of	O
web2py	B-Application
dynamically	O
and	O
transparently	O
generates	O
SQL	B-Language
queries	O
and	O
runs	O
on	O
multiple	O
compatible	O
database	O
backend	O
without	O
the	O
need	O
for	O
database-specific	O
SQL	B-Language
commands	O
(	O
though	O
SQL	B-Language
commands	O
can	O
be	O
issued	O
explicitly	O
)	O
.	O
</s>
<s>
SQLite	B-Language
is	O
included	O
in	O
Python	B-Language
and	O
is	O
the	O
default	O
web2py	B-Application
database	O
.	O
</s>
<s>
A	O
connection	O
string	O
change	O
allows	O
connection	O
to	O
Firebird	B-Application
,	O
IBM	B-Application
Db2	I-Application
,	O
Informix	B-Application
,	O
Ingres	B-Application
,	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
,	O
MySQL	B-Application
,	O
Oracle	B-General_Concept
,	O
PostgreSQL	B-Application
,	O
and	O
Google	B-Application
App	I-Application
Engine	I-Application
(	O
GAE	O
)	O
with	O
some	O
caveats	O
.	O
</s>
<s>
Distributed	B-General_Concept
transactions	I-General_Concept
:	O
</s>
<s>
Since	O
web2py	B-Application
v1.17	O
with	O
PostgreSQL	B-Application
v8.2	O
and	O
later	O
,	O
because	O
it	O
provides	O
API	B-General_Concept
for	O
two-phase	B-General_Concept
commits	I-General_Concept
.	O
</s>
<s>
Since	O
web2py	B-Application
v1.70.1	O
with	O
Firebird	B-Application
and	O
MySQL	B-Application
(	O
experimental	O
)	O
.	O
</s>
<s>
GAE	O
is	O
not	O
a	O
relational	O
store	O
,	O
but	O
web2py	B-Application
emulates	O
certain	O
operations	O
.	O
</s>
<s>
The	O
DAL	B-Application
is	O
fast	O
,	O
at	O
least	O
comparable	O
with	O
SQLAlchemy	B-Application
and	O
Storm	B-Application
.	O
</s>
<s>
Web2py	B-Application
implements	O
a	O
DAL	B-Application
,	O
not	O
an	O
ORM	B-General_Concept
.	O
</s>
<s>
An	O
ORM	B-General_Concept
maps	O
database	O
tables	O
into	O
classes	O
representing	O
logical	O
abstractions	O
from	O
the	O
database	O
layer	O
(	O
e.g.	O
,	O
a	O
User	O
class	O
or	O
a	O
PurchaseOrder	O
class	O
)	O
,	O
and	O
maps	O
records	O
into	O
instances	O
of	O
those	O
classes	O
.	O
</s>
<s>
The	O
DAL	B-Application
instead	O
maps	O
database	O
tables	O
and	O
records	O
into	O
instances	O
of	O
classes	O
representing	O
sets	O
and	O
records	O
instead	O
of	O
higher-level	O
abstractions	O
.	O
</s>
<s>
It	O
has	O
very	O
similar	O
syntax	O
to	O
an	O
ORM	B-General_Concept
but	O
it	O
is	O
faster	O
,	O
and	O
can	O
map	B-General_Concept
almost	O
any	O
SQL	B-Language
expressions	O
into	O
DAL	B-Application
expressions	O
.	O
</s>
<s>
The	O
DAL	B-Application
can	O
be	O
used	O
independently	O
of	O
the	O
rest	B-Protocol
of	O
web2py	B-Application
.	O
</s>
<s>
Here	O
are	O
some	O
examples	O
of	O
DAL	B-Application
syntax	O
:	O
</s>
<s>
The	O
latest	O
version	O
of	O
the	O
DAL	B-Application
has	O
support	O
for	O
2D	O
GIS	O
functions	O
with	O
Spatialite	O
and	O
PostGIS	O
.	O
</s>
<s>
The	O
current	O
API	B-General_Concept
are	O
experimental	O
because	O
of	O
a	O
possible	O
move	O
to	O
3D	O
APIs	B-General_Concept
.	O
</s>
<s>
web2py	B-Application
supports	O
database	O
migrations	O
—	O
change	O
the	O
definition	O
of	O
a	O
table	O
and	O
web2py	B-Application
ALTERs	O
the	O
table	O
accordingly	O
.	O
</s>
<s>
Migrations	O
are	O
automatic	O
,	O
but	O
can	O
be	O
disabled	O
for	O
any	O
table	O
,	O
and	O
migration	B-General_Concept
is	O
typically	O
disabled	O
when	O
an	O
application	O
is	O
ready	O
for	O
live	O
distribution	O
.	O
</s>
<s>
Migrations	O
and	O
migration	B-General_Concept
attempts	O
are	O
logged	O
,	O
documenting	O
the	O
changes	O
.	O
</s>
<s>
SQLite	B-Language
cannot	O
alter	O
table	O
and	O
change	O
a	O
column	O
type	O
,	O
but	O
rather	O
simply	O
stores	O
new	O
values	O
according	O
to	O
the	O
new	O
type	O
.	O
</s>
<s>
Web2py	B-Application
code	O
is	O
released	O
under	O
GNU	B-Application
Lesser	I-Application
General	I-Application
Public	I-Application
License	I-Application
(	O
LGPL	B-Application
)	O
version	O
3	O
as	O
of	O
web2py	B-Application
version	O
1.91.1	O
.	O
</s>
<s>
Web2py	B-Application
code	O
before	O
version	O
1.91.1	O
was	O
released	O
under	O
GNU	O
GPL	O
v2.0	O
with	O
commercial	O
exception	O
.	O
</s>
<s>
Various	O
third-party	O
packages	O
distributed	O
with	O
web2py	B-Application
have	O
their	O
own	O
licenses	O
,	O
generally	O
public	O
domain	O
,	O
MIT	O
or	O
BSD-type	O
licenses	O
.	O
</s>
<s>
Applications	O
built	O
with	O
web2py	B-Application
are	O
not	O
covered	O
by	O
the	O
LGPL	B-Application
license	I-Application
.	O
</s>
<s>
Web2py	B-Application
is	O
copyrighted	O
by	O
Massimo	O
DiPierro	O
.	O
</s>
<s>
The	O
web2py	B-Application
trademark	O
is	O
owned	O
by	O
Massimo	O
DiPierro	O
.	O
</s>
<s>
In	O
2011	O
InfoWorld	O
ranked	O
web2py	B-Application
highest	O
among	O
the	O
top	O
six	O
Python	B-Language
web	B-Application
frameworks	I-Application
,	O
awarded	O
web2py	B-Application
the	O
Bossie	O
award	O
2011	O
for	O
best	O
open	O
source	O
application	O
development	O
software	O
.	O
</s>
<s>
In	O
2012	O
web2py	B-Application
won	O
the	O
InfoWorld	O
Technology	O
of	O
the	O
Year	O
award	O
.	O
</s>
