<s>
In	O
computer	B-Architecture
and	O
telecommunications	O
networks	O
,	O
presence	B-Protocol
information	I-Protocol
is	O
a	O
status	O
indicator	O
that	O
conveys	O
ability	O
and	O
willingness	O
of	O
a	O
potential	O
communication	O
partner	O
—	O
for	O
example	O
a	O
user	O
—	O
to	O
communicate	O
.	O
</s>
<s>
A	O
user	O
's	O
client	B-Protocol
provides	O
presence	B-Protocol
information	I-Protocol
(	O
presence	O
state	O
)	O
via	O
a	O
network	O
connection	O
to	O
a	O
presence	B-Protocol
service	I-Protocol
,	O
which	O
is	O
stored	O
in	O
what	O
constitutes	O
his	O
personal	O
availability	O
record	O
(	O
called	O
a	O
presentity	B-Protocol
)	O
and	O
can	O
be	O
made	O
available	O
for	O
distribution	O
to	O
other	O
users	O
(	O
called	O
watchers	O
)	O
to	O
convey	O
their	O
availability	O
for	O
communication	O
.	O
</s>
<s>
Presence	B-Protocol
information	I-Protocol
has	O
wide	O
application	O
in	O
many	O
communication	O
services	O
and	O
is	O
one	O
of	O
the	O
innovations	O
driving	O
the	O
popularity	O
of	O
instant	B-Application
messaging	I-Application
or	O
recent	O
implementations	O
of	O
voice	B-Application
over	I-Application
IP	I-Application
clients	O
.	O
</s>
<s>
A	O
user	O
client	B-Protocol
may	O
publish	O
a	O
presence	O
state	O
to	O
indicate	O
its	O
current	O
communication	O
status	O
.	O
</s>
<s>
The	O
most	O
common	O
use	O
of	O
presence	O
today	O
is	O
to	O
display	O
an	O
indicator	O
icon	O
on	O
instant	B-Application
messaging	I-Application
clients	O
,	O
typically	O
from	O
a	O
choice	O
of	O
graphic	O
symbols	O
with	O
easy-to-convey	O
meanings	O
,	O
and	O
a	O
list	O
of	O
corresponding	O
text	O
descriptions	O
of	O
each	O
of	O
the	O
states	O
.	O
</s>
<s>
Such	O
states	O
exist	O
in	O
many	O
variations	O
across	O
different	O
modern	O
instant	B-Application
messaging	I-Application
clients	O
.	O
</s>
<s>
Current	O
standards	O
support	O
a	O
rich	O
choice	O
of	O
additional	O
presence	O
attributes	O
that	O
can	O
be	O
used	O
for	O
presence	B-Protocol
information	I-Protocol
,	O
such	O
as	O
user	O
mood	O
,	O
location	O
,	O
or	O
free	O
text	O
status	O
.	O
</s>
<s>
This	O
idea	O
is	O
already	O
familiar	O
to	O
instant	B-Application
messaging	I-Application
users	O
who	O
have	O
their	O
status	O
set	O
to	O
"	O
Away	O
"	O
(	O
or	O
equivalent	O
)	O
if	O
their	O
computer	B-Architecture
keyboard	O
is	O
inactive	O
for	O
some	O
time	O
.	O
</s>
<s>
Extension	O
to	O
other	O
devices	O
could	O
include	O
whether	O
the	O
user	O
's	O
cell	O
phone	O
is	O
on	O
,	O
whether	O
they	O
are	O
logged	O
into	O
their	O
computer	B-Architecture
,	O
or	O
perhaps	O
checking	O
their	O
electronic	O
calendar	O
to	O
see	O
if	O
they	O
are	O
in	O
a	O
meeting	O
or	O
on	O
vacation	O
.	O
</s>
<s>
XMPP	B-Protocol
,	O
discussed	O
below	O
,	O
allows	O
for	O
MPOP	O
by	O
assigning	O
each	O
client	B-Protocol
a	O
"	O
resource	O
"	O
(	O
a	O
specific	O
identifier	O
)	O
and	O
a	O
priority	O
number	O
for	O
each	O
resource	O
.	O
</s>
<s>
Presence	O
is	O
highly	O
sensitive	O
information	O
and	O
in	O
non-trivial	O
systems	O
a	O
presentity	B-Protocol
may	O
define	O
limits	O
to	O
which	O
its	O
presence	B-Protocol
information	I-Protocol
may	O
be	O
revealed	O
to	O
different	O
watchers	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
worker	O
may	O
only	O
want	O
colleagues	O
to	O
see	O
detailed	O
presence	B-Protocol
information	I-Protocol
during	O
office	O
hours	O
.	O
</s>
<s>
Basic	O
versions	O
of	O
this	O
idea	O
are	O
already	O
common	O
in	O
instant	B-Application
messaging	I-Application
clients	O
as	O
a	O
"	O
Blocking	O
"	O
facility	O
,	O
where	O
users	O
can	O
appear	O
as	O
unavailable	O
to	O
selected	O
watchers	O
.	O
</s>
<s>
Presence	O
,	O
particularly	O
MPOP	O
,	O
requires	O
collaboration	O
between	O
a	O
number	O
of	O
electronic	O
devices	O
(	O
for	O
example	O
IM	B-Application
client	B-Protocol
,	O
home	O
phone	O
,	O
cell	O
phone	O
,	O
and	O
electronic	O
calendar	O
)	O
and	O
the	O
presence	B-Protocol
services	I-Protocol
each	O
of	O
them	O
are	O
connected	O
with	O
.	O
</s>
<s>
For	O
presence	O
to	O
universally	O
work	O
with	O
MPOP	O
support	O
,	O
multiple	O
devices	O
must	O
be	O
able	O
to	O
not	O
only	O
intercommunicate	O
among	O
each	O
other	O
,	O
the	O
status	O
information	O
must	O
also	O
be	O
appropriately	O
handled	O
by	O
all	O
other	O
interoperable	O
,	O
connected	O
presence	B-Protocol
services	I-Protocol
and	O
the	O
MPOP	O
scheme	O
for	O
their	O
clients	O
.	O
</s>
<s>
2.5G	O
and	O
,	O
even	O
more	O
so	O
,	O
3G	B-Architecture
cell	O
phone	O
networks	O
can	O
support	O
management	O
and	O
access	O
of	O
presence	B-Protocol
information	I-Protocol
services	O
for	O
mobile	O
users	O
cell	O
phone	O
handsets	O
.	O
</s>
<s>
Presence	B-Protocol
information	I-Protocol
is	O
a	O
growing	O
tool	O
towards	O
more	O
effective	O
and	O
efficient	O
communication	O
within	O
a	O
business	O
setting	O
.	O
</s>
<s>
Presence	B-Protocol
information	I-Protocol
allows	O
you	O
to	O
instantly	O
see	O
who	O
is	O
available	O
in	O
your	O
corporate	O
network	O
,	O
giving	O
more	O
flexibility	O
to	O
set	O
up	O
short-term	O
meetings	O
and	O
conference	O
calls	O
.	O
</s>
<s>
An	O
example	O
of	O
the	O
time-saving	O
aspect	O
of	O
presence	B-Protocol
information	I-Protocol
is	O
a	O
driver	O
with	O
a	O
GPS	O
;	O
he/she	O
can	O
be	O
tracked	O
and	O
sent	O
messages	O
on	O
upcoming	O
traffic	O
patterns	O
that	O
,	O
in	O
return	O
,	O
save	O
time	O
and	O
money	O
.	O
</s>
<s>
According	O
to	O
IDC	O
surveys	O
,	O
employees	O
"	O
often	O
feel	O
that	O
IM	B-Application
gives	O
their	O
workdays	O
the	O
kind	O
of	O
'	O
flow	O
 '	O
that	O
they	O
feel	O
when	O
sitting	O
directly	O
among	O
their	O
colleagues	O
,	O
being	O
able	O
to	O
ask	O
questions	O
of	O
them	O
,	O
and	O
getting	O
the	O
kind	O
of	O
quick	O
responses	O
that	O
allow	O
them	O
to	O
drive	O
on	O
to	O
the	O
next	O
task	O
"	O
.	O
</s>
<s>
With	O
presence	B-Protocol
information	I-Protocol
,	O
privacy	O
of	O
the	O
users	O
can	O
become	O
an	O
issue	O
.	O
</s>
<s>
Therefore	O
,	O
a	O
concern	O
of	O
presence	B-Protocol
information	I-Protocol
is	O
to	O
determine	O
how	O
far	O
the	O
companies	O
want	O
to	O
go	O
with	O
staying	O
connected	O
.	O
</s>
<s>
In	O
1999	O
,	O
a	O
group	O
called	O
the	O
Instant	B-Application
Message	I-Application
and	O
Presence	O
Protocol	O
(	O
IMPP	O
)	O
working	O
group	O
(	O
WG	O
)	O
,	O
was	O
formed	O
within	O
the	O
Internet	O
Engineering	O
Task	O
Force	O
organization	O
(	O
IETF	O
)	O
in	O
order	O
to	O
develop	O
protocols	O
and	O
data	O
formats	O
for	O
simple	O
presence	O
and	O
instant	B-Application
messaging	I-Application
services	O
.	O
</s>
<s>
Instead	O
it	O
issued	O
a	O
common	O
profile	O
for	O
presence	O
and	O
instant	B-Application
messaging	I-Application
(	O
CPP	O
)	O
which	O
defined	O
semantics	O
for	O
common	O
services	O
of	O
presence	O
to	O
facilitate	O
the	O
creation	O
of	O
gateways	O
between	O
presence	B-Protocol
services	I-Protocol
.	O
</s>
<s>
In	O
2001	O
,	O
the	O
SIMPLE	O
working	O
group	O
was	O
formed	O
within	O
IETF	O
to	O
develop	O
a	O
suite	O
of	O
CPP-compliant	O
standards	O
for	O
presence	O
and	O
instant	B-Application
messaging	I-Application
applications	O
over	O
the	O
Session	B-Application
Initiation	I-Application
Protocol	I-Application
(	O
SIP	B-Application
)	O
.	O
</s>
<s>
The	O
SIMPLE	O
activity	O
specifies	O
extensions	O
to	O
the	O
SIP	B-Application
protocol	O
which	O
deal	O
with	O
a	O
publish	O
and	O
subscribe	O
mechanism	O
for	O
presence	B-Protocol
information	I-Protocol
and	O
sending	O
instant	B-Application
messages	I-Application
.	O
</s>
<s>
This	O
is	O
in	O
addition	O
to	O
the	O
complexity	O
of	O
the	O
SIP	B-Application
protocol	O
stack	O
on	O
which	O
SIMPLE	O
is	O
based	O
.	O
</s>
<s>
At	O
the	O
end	O
of	O
2001	O
,	O
Nokia	O
,	O
Motorola	O
,	O
and	O
Ericsson	O
formed	O
the	O
Wireless	O
Village	O
(	O
WV	O
)	O
initiative	O
to	O
define	O
a	O
set	O
of	O
universal	O
specifications	O
for	O
mobile	O
Instant	B-Application
Messaging	I-Application
and	O
Presence	B-Protocol
Services	I-Protocol
(	O
IMPS	O
)	O
and	O
presence	B-Protocol
services	I-Protocol
for	O
wireless	O
networks	O
.	O
</s>
<s>
the	O
XML-based	O
OMA	O
Instant	B-Application
Messaging	I-Application
and	O
Presence	B-Protocol
Service	I-Protocol
(	O
IMPS	O
)	O
.	O
</s>
<s>
IMPS	O
defines	O
a	O
system	O
architecture	O
,	O
syntax	O
,	O
and	O
semantics	O
for	O
representation	O
of	O
presence	B-Protocol
information	I-Protocol
and	O
a	O
set	O
of	O
protocols	O
for	O
the	O
four	O
primary	O
features	O
:	O
presence	O
,	O
IM	B-Application
,	O
groups	O
,	O
and	O
shared	O
content	O
.	O
</s>
<s>
The	O
XML-based	O
XMPP	B-Protocol
or	O
Extensible	B-Protocol
Messaging	I-Protocol
and	I-Protocol
Presence	I-Protocol
Protocol	I-Protocol
was	O
designed	O
and	O
is	O
currently	O
maintained	O
by	O
the	O
XMPP	B-Protocol
Standards	I-Protocol
Foundation	I-Protocol
.	O
</s>
<s>
This	O
IM	B-Application
protocol	O
,	O
which	O
is	O
a	O
robust	O
and	O
widely	O
extended	O
protocol	O
,	O
is	O
also	O
the	O
protocol	O
used	O
in	O
the	O
commercial	O
implementation	O
of	O
Google	B-Application
Talk	I-Application
and	O
Facebook	B-Protocol
Chat	I-Protocol
.	O
</s>
<s>
In	O
October	O
2004	O
,	O
the	O
XMPP	B-Protocol
working	O
group	O
at	O
IETF	O
published	O
the	O
documents	O
RFC	O
3920	O
,	O
RFC	O
3921	O
,	O
RFC	O
3922	O
and	O
RFC	O
3923	O
,	O
to	O
standardize	O
the	O
core	O
XMPP	B-Protocol
protocol	I-Protocol
.	O
</s>
