<s>
The	O
UAProf	B-General_Concept
(	O
User	O
Agent	O
Profile	O
)	O
specification	O
is	O
concerned	O
with	O
capturing	O
capability	O
and	O
preference	O
information	O
for	O
wireless	O
devices	O
.	O
</s>
<s>
UAProf	B-General_Concept
is	O
related	O
to	O
the	O
Composite	O
Capability/Preference	O
Profiles	O
Specification	O
created	O
by	O
the	O
World	O
Wide	O
Web	O
Consortium	O
.	O
</s>
<s>
UAProf	B-General_Concept
is	O
based	O
on	O
RDF	O
.	O
</s>
<s>
UAProf	B-General_Concept
files	O
typically	O
have	O
the	O
file	O
extensions	O
rdf	O
or	O
xml	B-Protocol
,	O
and	O
are	O
usually	O
served	O
with	O
mimetype	O
application/xml	O
.	O
</s>
<s>
They	O
are	O
an	O
XML-based	O
file	O
format	O
.	O
</s>
<s>
A	O
UAProf	B-General_Concept
file	O
describes	O
the	O
capabilities	O
of	O
a	O
mobile	O
handset	O
,	O
including	O
Vendor	O
,	O
Model	O
,	O
Screensize	O
,	O
Multimedia	O
Capabilities	O
,	O
Character	O
Set	O
support	O
,	O
and	O
more	O
.	O
</s>
<s>
A	O
mobile	O
handset	O
sends	O
a	O
header	O
within	O
an	O
http	O
request	O
,	O
containing	O
the	O
URL	O
to	O
its	O
UAProf	B-General_Concept
.	O
</s>
<s>
The	O
http	O
header	O
is	O
usually	O
X-WAP-Profile	O
:	O
,	O
but	O
sometimes	O
may	O
look	O
more	O
like	O
19-Profile	O
:	O
,	O
WAP-Profile	O
:	O
or	O
a	O
number	O
of	O
other	O
similar	O
headers	O
.	O
</s>
<s>
UAProf	B-General_Concept
production	O
for	O
a	O
device	O
is	O
voluntary	O
:	O
for	O
GSM	O
devices	O
,	O
the	O
UAProf	B-General_Concept
is	O
normally	O
produced	O
by	O
the	O
vendor	O
of	O
the	O
device	O
(	O
e.g.	O
</s>
<s>
Nokia	O
,	O
Samsung	B-Application
,	O
LG	O
)	O
whereas	O
for	O
CDMA	B-Protocol
/	O
BREW	B-Application
devices	O
it	O
's	O
more	O
common	O
for	O
the	O
UAProf	B-General_Concept
to	O
be	O
produced	O
by	O
the	O
telecommunications	O
company	O
.	O
</s>
<s>
A	O
content	O
delivery	O
system	O
(	O
such	O
as	O
a	O
WAP	B-Protocol
site	I-Protocol
)	O
can	O
use	O
UAProf	B-General_Concept
to	O
adapt	O
content	O
for	O
display	O
,	O
or	O
to	O
decide	O
what	O
items	O
to	O
offer	O
for	O
download	O
.	O
</s>
<s>
However	O
,	O
drawbacks	O
to	O
relying	O
solely	O
on	O
UAProf	B-General_Concept
are	O
(	O
See	O
also	O
)	O
:	O
</s>
<s>
Retrieving	O
and	O
parsing	O
UAProfs	B-General_Concept
in	O
real-time	O
is	O
slow	O
and	O
can	O
add	O
substantial	O
overhead	O
to	O
any	O
given	O
web	O
request	O
:	O
necessitating	O
the	O
creation	O
of	O
a	O
Device	O
Description	O
Repository	O
to	O
cache	O
the	O
UAProfs	B-General_Concept
in	O
,	O
and	O
a	O
workflow	O
to	O
refresh	O
UAProfs	B-General_Concept
to	O
check	O
for	O
deprecation	O
.	O
</s>
<s>
There	O
is	O
no	O
industry-wide	O
data	O
quality	O
standard	O
for	O
the	O
data	O
within	O
each	O
field	O
in	O
an	O
UAProf	B-General_Concept
.	O
</s>
<s>
The	O
UAProf	B-General_Concept
document	O
itself	O
does	O
not	O
contain	O
the	O
user	O
agents	O
of	O
the	O
devices	O
it	O
might	O
apply	O
to	O
in	O
the	O
schema	O
(	O
Nokia	O
put	O
it	O
in	O
the	O
comments	O
)	O
.	O
</s>
<s>
UAProf	B-General_Concept
headers	O
can	O
often	O
be	O
plain	O
wrong	O
.	O
</s>
<s>
UAProf	B-General_Concept
device	O
profiles	O
are	O
one	O
of	O
the	O
sources	O
of	O
device	O
capability	O
information	O
for	O
WURFL	B-Application
,	O
which	O
maps	O
the	O
UAProfile	O
schema	O
to	O
its	O
own	O
with	O
many	O
other	O
items	O
and	O
boolean	O
fields	O
relating	O
to	O
device	O
markup	O
,	O
multimedia	O
capabilities	O
and	O
more	O
.	O
</s>
<s>
This	O
XML	B-Protocol
data	O
is	O
keyed	O
on	O
the	O
User-Agent	O
:	O
header	O
in	O
a	O
web	O
request	O
.	O
</s>
<s>
Another	O
approach	O
to	O
the	O
problem	O
is	O
to	O
combine	O
real-time	O
derived	O
information	O
,	O
component	O
analysis	O
,	O
manual	O
data	O
and	O
UAProfiles	O
to	O
deal	O
with	O
the	O
actual	O
device	O
itself	O
rather	O
than	O
the	O
idealised	O
representation	O
of	O
"	O
offline	O
"	O
approaches	O
such	O
as	O
UAProf	B-General_Concept
or	O
WURFL	B-Application
.	O
</s>
<s>
This	O
approach	O
allows	O
detection	O
of	O
devices	O
modified	O
by	O
the	O
user	O
,	O
Windows	B-Operating_System
Mobile	I-Operating_System
devices	O
,	O
Legacy	O
devices	O
,	O
Spiders	B-Protocol
and	O
Bots	B-Protocol
,	O
and	O
is	O
evidenced	O
in	O
at	O
least	O
one	O
commercially	O
available	O
system	O
.	O
</s>
<s>
The	O
W3C	O
MWI	O
(	O
Mobile	O
Web	O
Initiative	O
)	O
and	O
the	O
associated	O
DDWG	O
(	O
Device	O
Description	O
Working	O
Group	O
)	O
,	O
recognising	O
the	O
difficulty	O
in	O
collecting	O
and	O
keeping	O
track	O
of	O
UAProfs	B-General_Concept
and	O
device	O
handset	O
information	O
,	O
and	O
the	O
practical	O
shortcomings	O
in	O
the	O
implementation	O
of	O
UAProf	B-General_Concept
across	O
the	O
industry	O
have	O
outlined	O
specifications	O
for	O
a	O
Device	O
Description	O
Repository	O
,	O
in	O
the	O
expectation	O
that	O
an	O
ecosystem	O
of	O
such	O
Repositories	O
will	O
eventually	O
eliminate	O
the	O
need	O
for	O
local	O
device	O
repositories	O
in	O
favour	O
of	O
a	O
web	O
service	O
ecosystem	O
.	O
</s>
