<s>
AS2	B-Protocol
(	O
Applicability	B-Protocol
Statement	I-Protocol
2	I-Protocol
)	O
is	O
a	O
specification	B-Application
on	O
how	O
to	O
transport	O
structured	O
business-to-business	O
data	O
securely	O
and	O
reliably	O
over	O
the	O
Internet	O
.	O
</s>
<s>
AS2	B-Protocol
was	O
created	O
in	O
2002	O
by	O
the	O
IETF	O
to	O
replace	O
AS1	B-Protocol
,	O
which	O
they	O
created	O
in	O
the	O
early	O
1990s	O
.	O
</s>
<s>
The	O
adoption	O
of	O
AS2	B-Protocol
grew	O
rapidly	O
throughout	O
the	O
early	O
2000s	O
because	O
major	O
players	O
in	O
the	O
retail	O
and	O
fast-moving	O
consumer	O
goods	O
industries	O
championed	O
AS2	B-Protocol
.	O
</s>
<s>
Walmart	O
was	O
the	O
first	O
major	O
retailer	O
to	O
require	O
its	O
suppliers	O
to	O
use	O
the	O
AS2	B-Protocol
protocol	O
instead	O
of	O
relying	O
on	O
dial-up	O
modems	O
for	O
ordering	O
goods	O
.	O
</s>
<s>
Many	O
other	O
industries	O
use	O
the	O
AS2	B-Protocol
protocol	O
,	O
including	O
healthcare	O
,	O
as	O
AS2	B-Protocol
meets	O
legal	O
HIPAA	O
requirements	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
AS2	B-Protocol
is	O
a	O
way	O
to	O
bypass	O
expensive	O
value-added	O
networks	O
previously	O
used	O
for	O
data	O
interchange	O
.	O
</s>
<s>
AS2	B-Protocol
is	O
specified	O
in	O
RFC	O
4130	O
,	O
and	O
is	O
based	O
on	O
HTTP	B-Protocol
and	O
S/MIME	B-Protocol
.	O
</s>
<s>
It	O
was	O
the	O
second	O
AS	O
protocol	O
developed	O
and	O
uses	O
the	O
same	O
signing	O
,	O
encryption	O
and	O
MDN	O
(	O
as	O
defined	O
by	O
)	O
conventions	O
used	O
in	O
the	O
original	O
AS1	B-Protocol
protocol	O
introduced	O
in	O
the	O
late	O
1990s	O
by	O
IETF	O
.	O
</s>
<s>
Files	O
are	O
encoded	O
as	O
"	O
attachments	O
"	O
in	O
a	O
standardized	O
S/MIME	B-Protocol
message	O
(	O
an	O
AS2	B-Protocol
message	O
)	O
.	O
</s>
<s>
AS2	B-Protocol
does	O
not	O
specify	O
the	O
contents	O
of	O
the	O
files	O
.	O
</s>
<s>
Usually	O
,	O
the	O
file	O
contents	O
are	O
in	O
a	O
standardized	O
format	O
that	O
is	O
separately	O
agreed	O
upon	O
,	O
such	O
as	O
XML	B-Protocol
or	O
EDIFACT	O
.	O
</s>
<s>
AS2	B-Protocol
messages	O
are	O
always	O
sent	O
using	O
the	O
HTTP	B-Protocol
or	O
HTTPS	B-Protocol
protocol	O
(	O
Secure	B-Protocol
Sockets	I-Protocol
Layer	I-Protocol
—	O
also	O
known	O
as	O
SSL	O
—	O
is	O
implied	O
by	O
HTTPS	B-Protocol
)	O
and	O
usually	O
use	O
the	O
"	O
POST	O
"	O
method	O
(	O
use	O
of	O
"	O
GET	O
"	O
is	O
rare	O
)	O
.	O
</s>
<s>
If	O
the	O
original	O
AS2	B-Protocol
message	O
requested	O
an	O
MDN	O
:	O
</s>
<s>
This	O
MDN	O
is	O
typically	O
signed	O
but	O
never	O
encrypted	O
(	O
unless	O
temporarily	O
encrypted	O
in	O
transit	O
via	O
HTTPS	B-Protocol
)	O
.	O
</s>
<s>
Upon	O
the	O
receipt	O
and	O
successful	O
verification	O
of	O
the	O
signature	O
on	O
the	O
MDN	O
,	O
the	O
original	O
sender	O
will	O
"	O
know	O
"	O
that	O
the	O
recipient	O
got	O
their	O
message	O
(	O
this	O
provides	O
the	O
"	O
Non-repudiation	O
"	O
element	O
of	O
AS2	B-Protocol
)	O
.	O
</s>
<s>
If	O
there	O
are	O
any	O
problems	O
receiving	O
or	O
interpreting	O
the	O
original	O
AS2	B-Protocol
message	O
,	O
a	O
"	O
failed	O
"	O
MDN	O
may	O
be	O
sent	O
back	O
.	O
</s>
<s>
However	O
,	O
part	O
of	O
the	O
AS2	B-Protocol
protocol	O
states	O
that	O
the	O
client	O
must	O
treat	O
a	O
lack	O
of	O
an	O
MDN	O
as	O
a	O
failure	O
as	O
well	O
,	O
so	O
some	O
AS2	B-Protocol
receivers	O
will	O
not	O
return	O
an	O
MDN	O
in	O
this	O
case	O
.	O
</s>
<s>
Like	O
any	O
other	O
AS	O
file	O
transfer	O
,	O
AS2	B-Protocol
file	O
transfers	O
typically	O
require	O
both	O
sides	O
of	O
the	O
exchange	O
to	O
trade	O
X.509	O
certificates	O
and	O
specific	O
"	O
trading	O
partner	O
"	O
names	O
before	O
any	O
transfers	O
can	O
take	O
place	O
.	O
</s>
<s>
AS2	B-Protocol
trading	O
partner	O
names	O
can	O
usually	O
be	O
any	O
valid	O
phrase	O
.	O
</s>
<s>
Unlike	O
AS1	B-Protocol
or	O
AS3	B-Protocol
file	O
transfers	O
,	O
AS2	B-Protocol
file	O
transfers	O
offer	O
several	O
"	O
MDN	O
return	O
"	O
options	O
instead	O
of	O
the	O
traditional	O
options	O
of	O
"	O
yes	O
"	O
or	O
"	O
no	O
"	O
.	O
</s>
<s>
Return	O
Synchronous	O
MDN	O
via	O
HTTP(S )	O
(	O
"	O
AS2	B-Protocol
Sync	O
"	O
)	O
-	O
This	O
popular	O
option	O
allows	O
AS2	B-Protocol
MDNs	O
to	O
be	O
returned	O
to	O
AS2	B-Protocol
message	O
sender	O
clients	O
over	O
the	O
same	O
HTTP	B-Protocol
connection	O
they	O
used	O
to	O
send	O
the	O
original	O
message	O
.	O
</s>
<s>
This	O
"	O
MDN	O
while	O
you	O
wait	O
"	O
capability	O
makes	O
"	O
AS2	B-Protocol
Sync	O
"	O
transfers	O
the	O
fastest	O
of	O
any	O
type	O
of	O
AS	O
file	O
transfer	O
,	O
but	O
it	O
also	O
keeps	O
this	O
flavor	O
of	O
MDN	O
requests	O
from	O
being	O
used	O
with	O
large	O
files	O
(	O
which	O
may	O
time	O
out	O
in	O
low-bandwidth	O
situations	O
)	O
.	O
</s>
<s>
Return	O
Asynchronous	O
MDN	O
via	O
HTTP(S )	O
(	O
a.k.a.	O
</s>
<s>
"	O
AS2	B-Protocol
Async	O
"	O
)	O
-	O
This	O
popular	O
option	O
allows	O
AS2	B-Protocol
MDNs	O
to	O
be	O
returned	O
to	O
the	O
AS2	B-Protocol
message	O
sender	O
's	O
server	O
later	O
over	O
a	O
different	O
HTTP	B-Protocol
connection	O
.	O
</s>
<s>
This	O
flavor	O
of	O
MDN	O
request	O
is	O
usually	O
used	O
if	O
large	O
files	O
are	O
involved	O
or	O
if	O
your	O
trading	O
partner	O
's	O
AS2	B-Protocol
server	O
has	O
poor	O
Internet	O
service	O
.	O
</s>
<s>
Return	O
(	O
Asynchronous	O
)	O
MDN	O
via	O
Email	O
-	O
This	O
rarely	O
used	O
option	O
allows	O
AS2	B-Protocol
MDNs	O
to	O
be	O
returned	O
to	O
AS2	B-Protocol
message	O
senders	O
via	O
email	O
rather	O
than	O
HTTP	B-Protocol
.	I-Protocol
</s>
<s>
Otherwise	O
,	O
it	O
is	O
similar	O
to	O
"	O
AS2	B-Protocol
Async	O
(	O
HTTP	B-Protocol
)	O
"	O
.	O
</s>
<s>
Do	O
not	O
return	O
MDN	O
-	O
This	O
option	O
works	O
like	O
it	O
does	O
in	O
any	O
other	O
AS	O
protocol	O
:	O
the	O
receiver	O
of	O
an	O
AS2	B-Protocol
message	O
with	O
this	O
option	O
set	O
simply	O
does	O
not	O
try	O
to	O
return	O
an	O
MDN	O
to	O
the	O
AS2	B-Protocol
message	O
sender	O
.	O
</s>
<s>
AS2	B-Protocol
filename	O
preservation	O
feature	O
will	O
be	O
used	O
to	O
communicate	O
the	O
filename	O
to	O
the	O
trading	O
partner	O
.	O
</s>
<s>
AS2	B-Protocol
vendors	O
are	O
currently	O
certifying	O
that	O
implementation	O
of	O
filename	O
communication	O
conforms	O
to	O
the	O
standard	O
and	O
is	O
interoperable	O
.	O
</s>
<s>
There	O
are	O
two	O
profiles	O
for	O
filename	O
preservation	O
being	O
optionally	O
tested	O
under	O
AS2	B-Protocol
testing	O
:	O
</s>
<s>
For	O
many	O
businesses	O
,	O
the	O
use	O
of	O
AS2	B-Protocol
and	O
electronic	O
data	O
interchange	O
(	O
EDI	O
)	O
is	O
not	O
a	O
choice	O
so	O
much	O
as	O
it	O
is	O
a	O
requirement	O
of	O
doing	O
business	O
with	O
a	O
large	O
customer	O
or	O
partner	O
.	O
</s>
<s>
That	O
said	O
,	O
AS2	B-Protocol
is	O
a	O
universal	O
protocol	O
that	O
has	O
benefits	O
,	O
from	O
both	O
business	O
and	O
technology	O
vantage	O
points	O
.	O
</s>
<s>
Cut	O
costs	O
by	O
using	O
the	O
web	O
for	O
EDI	O
file	O
transfers	O
,	O
AS2	B-Protocol
reduces	O
the	O
cost	O
of	O
transactions	O
from	O
expensive	O
VANs	O
.	O
</s>
<s>
Extend	O
EDI	O
to	O
more	O
partners	O
;	O
with	O
lower	O
costs	O
and	O
universal	O
web	O
connectivity	O
,	O
AS2	B-Protocol
allows	O
organizations	O
to	O
implement	O
EDI	O
with	O
partners	O
worldwide	O
that	O
have	O
little	O
EDI	O
infrastructure	O
.	O
</s>
<s>
Universal	O
solution	O
—	O
AS2	B-Protocol
is	O
established	O
and	O
tested	O
,	O
so	O
no	O
one	O
has	O
to	O
re-invent	O
the	O
wheel	O
.	O
</s>
<s>
Leverage	O
the	O
web	O
:	O
if	O
an	O
organization	O
can	O
share	O
data	O
securely	O
via	O
the	O
web	O
,	O
they	O
already	O
have	O
much	O
of	O
the	O
infrastructure	O
for	O
AS2	B-Protocol
.	O
</s>
<s>
Unlimited	O
EDI	O
data	O
—	O
there	O
are	O
no	O
practical	O
limitations	O
on	O
transaction	O
sizes	O
via	O
the	O
web	O
,	O
and	O
AS2	B-Protocol
includes	O
features	O
for	O
managing	O
large	O
transfers	O
.	O
</s>
<s>
Payload	O
Agnostic	O
—	O
AS2	B-Protocol
can	O
be	O
used	O
to	O
transport	O
any	O
type	O
of	O
document	O
.	O
</s>
<s>
While	O
EDI	O
X12	O
,	O
EDIFACT	O
and	O
XML	B-Protocol
are	O
common	O
,	O
any	O
mutually	O
agreed-upon	O
format	O
may	O
be	O
transferred	O
.	O
</s>
