<s>
User-Mode	B-Application
Driver	I-Application
Framework	I-Application
(	O
UMDF	B-Application
)	O
is	O
a	O
device-driver	O
development	O
platform	O
first	O
introduced	O
with	O
Microsoft	O
's	O
Windows	B-Application
Vista	I-Application
operating	I-Application
system	I-Application
,	O
and	O
is	O
also	O
available	O
for	O
Windows	B-Application
XP	I-Application
.	O
</s>
<s>
The	O
User-Mode	B-Application
Driver	I-Application
Framework	I-Application
insulates	O
the	O
kernel	O
from	O
the	O
problems	O
of	O
direct	O
driver	O
access	O
,	O
instead	O
providing	O
a	O
new	O
class	O
of	O
driver	O
with	O
a	O
dedicated	O
application	B-Application
programming	I-Application
interface	I-Application
at	O
the	O
user	O
level	O
of	O
interrupts	O
and	O
memory	O
management	O
.	O
</s>
<s>
This	O
is	O
particularly	O
useful	O
for	O
devices	O
that	O
are	O
intermittently	O
connected	O
to	O
the	O
system	O
or	O
support	O
hot	B-Device
swapping	I-Device
via	O
a	O
bus	O
technology	O
such	O
as	O
USB	B-Protocol
or	O
FireWire	B-Protocol
.	O
</s>
<s>
According	O
to	O
Microsoft	O
,	O
UMDF	B-Application
drivers	O
are	O
simpler	O
to	O
write	O
and	O
debug	O
than	O
kernel-mode	O
drivers	O
.	O
</s>
<s>
However	O
,	O
UMDF	B-Application
would	O
not	O
be	O
used	O
for	O
performance-intensive	O
or	O
highly	O
stateful	B-Application
devices	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
the	O
UMDF	B-Application
was	O
shipped	O
as	O
part	O
of	O
Windows	B-Device
Media	I-Device
Player	I-Device
version	O
10	O
on	O
2004-10-12	O
.	O
</s>
<s>
Code-named	O
"	O
Crescent	O
"	O
,	O
it	O
was	O
designed	O
to	O
support	O
the	O
Media	B-Protocol
Transfer	I-Protocol
Protocol	I-Protocol
driver	O
,	O
and	O
no	O
public	O
interfaces	O
or	O
documentation	O
were	O
provided	O
for	O
it	O
.	O
</s>
<s>
Later	O
,	O
Microsoft	O
decided	O
to	O
turn	O
UMDF	B-Application
into	O
a	O
device	O
driver	O
development	O
platform	O
.	O
</s>
<s>
User-Mode	B-Application
Driver	I-Application
Framework	I-Application
1.5-1.9	O
,	O
supports	O
Windows	B-Application
XP	I-Application
and	O
newer	O
.	O
</s>
<s>
User-Mode	B-Application
Driver	I-Application
Framework	I-Application
1.11	O
,	O
supports	O
Windows	B-Application
Vista	I-Application
and	O
later	O
,	O
and	O
Windows	B-Device
Server	I-Device
2008	I-Device
and	O
later	O
.	O
</s>
<s>
User-Mode	B-Application
Driver	I-Application
Framework	I-Application
2.0	O
,	O
which	O
supports	O
Windows	B-Device
8.1	I-Device
and	O
newer	O
.	O
</s>
<s>
A	O
UMDF	B-Application
Driver	O
is	O
a	O
DLL	O
based	O
on	O
Microsoft	O
's	O
Component	B-Application
Object	I-Application
Model	I-Application
(	O
COM	O
)	O
.	O
</s>
<s>
However	O
,	O
UMDF	B-Application
does	O
not	O
use	O
COM	O
for	O
loading	O
,	O
unloading	O
,	O
or	O
controlling	O
concurrency	B-Operating_System
;	O
it	O
only	O
uses	O
COM	O
as	O
a	O
programming	O
pattern	O
,	O
for	O
example	O
exploiting	O
COM	O
's	O
IUnknown	B-Application
interface	O
.	O
</s>
<s>
At	O
startup	O
,	O
UMDF	B-Application
calls	O
DllGetClassObject	O
to	O
get	O
a	O
pointer	O
to	O
an	O
IClassFactory	O
interface	O
in	O
the	O
driver	O
and	O
then	O
uses	O
the	O
CreateInstance	O
method	O
of	O
the	O
IClassFactory	O
interface	O
to	O
create	O
an	O
instance	O
of	O
the	O
driver	O
callback	O
object	O
.	O
</s>
