<s>
In	O
computing	O
,	O
an	O
open	B-Application
platform	I-Application
describes	O
a	O
software	O
system	O
which	O
is	O
based	O
on	O
open	O
standards	O
,	O
such	O
as	O
published	O
and	O
fully	O
documented	O
external	O
application	B-Application
programming	I-Application
interfaces	I-Application
(	O
API	B-Application
)	O
that	O
allow	O
using	O
the	O
software	O
to	O
function	O
in	O
other	O
ways	O
than	O
the	O
original	O
programmer	O
intended	O
,	O
without	O
requiring	O
modification	O
of	O
the	O
source	O
code	O
.	O
</s>
<s>
The	O
opposite	O
is	O
a	O
closed	B-Application
platform	I-Application
.	O
</s>
<s>
An	O
open	B-Application
platform	I-Application
does	O
not	O
mean	O
it	O
is	O
open	B-License
source	I-License
,	O
however	O
most	O
open	B-Application
platforms	I-Application
have	O
multiple	O
implementations	O
of	O
APIs	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
Common	B-Language
Gateway	I-Language
Interface	I-Language
(	O
CGI	O
)	O
is	O
implemented	O
by	O
open	B-License
source	I-License
web	B-Application
servers	I-Application
as	O
well	O
as	O
Microsoft	B-Application
Internet	I-Application
Information	I-Application
Server	I-Application
(	O
IIS	O
)	O
.	O
</s>
<s>
An	O
open	B-Application
platform	I-Application
can	O
consist	O
of	O
software	O
components	O
or	O
modules	O
that	O
are	O
either	O
proprietary	B-Application
or	O
open	B-License
source	I-License
or	O
both	O
.	O
</s>
<s>
It	O
can	O
also	O
exist	O
as	O
a	O
part	O
of	O
closed	B-Application
platform	I-Application
,	O
such	O
as	O
CGI	O
,	O
which	O
is	O
an	O
open	B-Application
platform	I-Application
,	O
while	O
many	O
servers	O
that	O
implement	O
CGI	O
also	O
have	O
other	O
proprietary	B-Application
parts	I-Application
that	O
are	O
not	O
part	O
of	O
the	O
open	B-Application
platform	I-Application
.	O
</s>
<s>
An	O
open	B-Application
platform	I-Application
implies	O
that	O
the	O
vendor	O
allows	O
,	O
and	O
perhaps	O
supports	O
,	O
the	O
ability	O
to	O
do	O
this	O
.	O
</s>
<s>
Using	O
an	O
open	B-Application
platform	I-Application
a	O
developer	O
could	O
add	O
features	O
or	O
functionality	O
that	O
the	O
platform	O
vendor	O
had	O
not	O
completed	O
or	O
had	O
not	O
conceived	O
of	O
.	O
</s>
<s>
An	O
open	B-Application
platform	I-Application
allows	O
the	O
developer	O
to	O
change	O
existing	O
functionality	O
,	O
as	O
the	O
specifications	O
are	O
publicly	O
available	O
open	O
standards	O
.	O
</s>
<s>
A	O
service-oriented	O
architecture	O
allows	O
applications	O
,	O
running	O
as	O
services	O
,	O
to	O
be	O
accessed	O
in	O
a	O
distributed	B-Architecture
computing	I-Architecture
environment	O
,	O
such	O
as	O
between	O
multiple	O
systems	O
or	O
across	O
the	O
Internet	O
.	O
</s>
