<s>
Bidirectional-streams	B-Protocol
Over	I-Protocol
Synchronous	I-Protocol
HTTP	I-Protocol
(	O
BOSH	B-Protocol
)	O
is	O
a	O
transport	B-Architecture
protocol	I-Architecture
that	O
emulates	O
a	O
bidirectional	O
stream	O
between	O
two	O
entities	O
(	O
such	O
as	O
a	B-Operating_System
client	I-Operating_System
and	I-Operating_System
a	I-Operating_System
server	I-Operating_System
)	O
by	O
using	O
multiple	O
synchronous	O
HTTP	B-Protocol
request/response	O
pairs	O
without	O
requiring	O
the	O
use	O
of	O
polling	B-General_Concept
or	O
asynchronous	O
chunking	O
.	O
</s>
<s>
For	O
applications	O
that	O
require	O
both	O
"	O
push	O
"	O
and	O
"	O
pull	O
"	O
communications	O
,	O
BOSH	B-Protocol
is	O
significantly	O
more	O
bandwidth-efficient	O
and	O
responsive	O
than	O
most	O
other	O
bidirectional	O
HTTP-based	O
transport	B-Architecture
protocols	I-Architecture
and	O
AJAX	B-Device
.	O
</s>
<s>
BOSH	B-Protocol
achieves	O
this	O
by	O
avoiding	O
HTTP	B-Protocol
polling	B-General_Concept
,	O
yet	O
it	O
does	O
so	O
without	O
resorting	O
to	O
chunked	O
HTTP	B-Protocol
responses	O
as	O
is	O
done	O
in	O
the	O
technique	O
known	O
as	O
Comet	B-General_Concept
.	O
</s>
<s>
To	O
date	O
,	O
BOSH	B-Protocol
has	O
been	O
used	O
mainly	O
as	O
a	O
transport	O
for	O
traffic	O
exchanged	O
between	O
Jabber/XMPP	B-Protocol
clients	O
and	O
servers	O
(	O
e.g.	O
,	O
to	O
facilitate	O
connections	O
from	O
web	O
clients	O
and	O
from	O
mobile	O
clients	O
on	O
intermittent	O
networks	O
)	O
.	O
</s>
<s>
For	O
"	O
push	O
"	O
,	O
a	O
BOSH	B-Protocol
client	O
starts	O
an	O
HTTP	B-Protocol
request	O
,	O
but	O
the	O
server	O
postpones	O
sending	O
a	O
reply	O
until	O
it	O
has	O
data	O
to	O
send	O
.	O
</s>
<s>
After	O
receiving	O
a	O
reply	O
,	O
the	O
client	O
immediately	O
makes	O
another	O
request	O
on	O
the	O
same	O
HTTP	B-Protocol
connection	O
,	O
so	O
the	O
server	O
can	O
always	O
send	O
data	O
to	O
the	O
client	O
without	O
waiting	O
for	O
the	O
client	O
to	O
poll	O
.	O
</s>
<s>
If	O
,	O
while	O
waiting	O
for	O
a	O
reply	O
,	O
the	O
client	O
needs	O
to	O
send	O
data	O
to	O
the	O
server	O
,	O
it	O
opens	O
a	O
second	O
HTTP	B-Protocol
connection	O
.	O
</s>
<s>
There	O
are	O
at	O
most	O
two	O
HTTP	B-Protocol
connections	O
open	O
at	O
a	O
time	O
,	O
one	O
on	O
which	O
the	O
server	O
can	O
send	O
data	O
as	O
a	O
reply	O
and	O
one	O
on	O
which	O
the	O
client	O
can	O
send	O
data	O
as	O
a	O
POST	O
.	O
</s>
<s>
"	O
Bidirectional-streams	B-Protocol
Over	I-Protocol
Synchronous	I-Protocol
HTTP	I-Protocol
(	O
BOSH	B-Protocol
)	O
"	O
and	O
"	O
XMPP	B-Protocol
over	O
BOSH	B-Protocol
"	O
are	O
stable	O
standards	O
of	O
the	O
XMPP	B-Protocol
Standards	I-Protocol
Foundation	I-Protocol
.	O
</s>
<s>
The	O
second	O
related	O
standard	O
XMPP	B-Protocol
Over	O
BOSH	B-Protocol
(	O
XEP-0206	O
)	O
defines	O
how	O
BOSH	B-Protocol
may	O
be	O
used	O
to	O
transport	O
XMPP	B-Protocol
stanzas	O
.	O
</s>
<s>
The	O
result	O
is	O
an	O
HTTP	B-Protocol
binding	O
for	O
XMPP	B-Protocol
communications	O
that	O
is	O
intended	O
to	O
be	O
used	O
in	O
situations	O
where	O
a	O
device	O
or	O
client	O
is	O
unable	O
to	O
maintain	O
a	O
long-lived	O
TCP	B-Protocol
connection	I-Protocol
to	O
an	O
XMPP	B-Protocol
server	O
.	O
</s>
