<s>
A	O
front-end	B-Application
processor	I-Application
(	O
FEP	O
)	O
,	O
or	O
a	O
communications	B-Application
processor	I-Application
,	O
is	O
a	O
small-sized	O
computer	O
which	O
interfaces	O
to	O
the	O
host	B-Device
computer	I-Device
a	O
number	O
of	O
networks	O
,	O
such	O
as	O
SNA	B-Architecture
,	O
or	O
a	O
number	O
of	O
peripheral	O
devices	O
,	O
such	O
as	O
terminals	B-General_Concept
,	O
disk	B-Device
units	I-Device
,	O
printers	O
and	O
tape	O
units	O
.	O
</s>
<s>
Data	O
is	O
transferred	O
between	O
the	O
host	B-Device
computer	I-Device
and	O
the	O
front-end	B-Application
processor	I-Application
using	O
a	O
high-speed	O
parallel	B-Device
interface	I-Device
.	O
</s>
<s>
The	O
front-end	B-Application
processor	I-Application
communicates	O
with	O
peripheral	O
devices	O
using	O
slower	O
serial	B-Protocol
interfaces	I-Protocol
,	O
usually	O
also	O
through	O
communication	O
networks	O
.	O
</s>
<s>
The	O
purpose	O
is	O
to	O
off-load	O
from	O
the	O
host	B-Device
computer	I-Device
the	O
work	O
of	O
managing	O
the	O
peripheral	O
devices	O
,	O
transmitting	O
and	O
receiving	O
messages	O
,	O
packet	O
assembly	O
and	O
disassembly	O
,	O
error	O
detection	O
,	O
and	O
error	O
correction	O
.	O
</s>
<s>
Two	O
examples	O
are	O
the	O
IBM	B-Device
3705	I-Device
Communications	I-Device
Controller	I-Device
and	O
the	O
Burroughs	O
Data	O
Communications	B-Application
Processor	I-Application
.	O
</s>
<s>
Sometimes	O
FEP	O
is	O
synonymous	O
with	O
a	O
communications	B-Application
controller	I-Application
,	O
although	O
the	O
latter	O
is	O
not	O
necessarily	O
as	O
flexible	O
.	O
</s>
<s>
Early	O
communications	B-Application
controllers	I-Application
such	O
as	O
the	O
IBM	B-Device
270x	I-Device
series	O
were	O
hard	O
wired	O
,	O
but	O
later	O
units	O
were	O
programmable	O
devices	O
.	O
</s>
<s>
Front-end	B-Application
processor	I-Application
is	O
also	O
used	O
in	O
a	O
more	O
general	O
sense	O
in	O
asymmetric	O
multi-processor	O
systems	O
.	O
</s>
<s>
Front-end	O
processes	O
relates	O
to	O
the	O
software	O
interface	O
between	O
the	O
user	O
(	O
client	B-Protocol
)	O
and	O
the	O
application	O
processes	O
(	O
server	B-Application
)	O
in	O
the	O
client/server	O
architecture	O
.	O
</s>
<s>
The	O
user	O
enters	O
input	O
(	O
data	O
)	O
into	O
the	O
front-end	O
process	O
where	O
it	O
is	O
collected	O
and	O
processed	O
in	O
such	O
a	O
way	O
that	O
it	O
conforms	O
to	O
what	O
the	O
receiving	O
application	O
(	O
back	O
end	O
)	O
on	O
the	O
server	B-Application
can	O
accept	O
and	O
process	O
.	O
</s>
<s>
As	O
an	O
example	O
,	O
the	O
user	O
enters	O
a	O
URL	O
into	O
a	O
GUI	B-Application
(	O
front-end	O
process	O
)	O
such	O
as	O
Microsoft	O
Internet	O
Explorer	O
.	O
</s>
<s>
The	O
GUI	B-Application
then	O
processes	O
the	O
URL	O
in	O
such	O
a	O
way	O
that	O
the	O
user	O
is	O
able	O
to	O
reach	O
or	O
access	O
the	O
intended	O
web	O
pages	O
on	O
the	O
web	O
server	B-Application
(	O
application	O
server	B-Application
known	O
as	O
the	O
“	O
back	O
end	O
”	O
process	O
)	O
.	O
</s>
<s>
Front-end	B-Application
processors	I-Application
or	O
communications	B-Application
processors	I-Application
relates	O
to	O
efficient	O
use	O
of	O
the	O
host	O
CPU	O
by	O
off-loading	O
processing	O
for	O
peripheral	O
control	O
,	O
as	O
an	O
example	O
,	O
to	O
another	O
device	O
or	O
controller	O
.	O
</s>
<s>
FEPs	O
are	O
responsible	O
for	O
linking	O
client	B-Protocol
applications	I-Protocol
and	O
their	O
associated	O
networks	O
to	O
host	B-Device
computer	I-Device
based	O
applications	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
the	O
Internet	O
and	O
of	O
IP	B-Protocol
as	O
a	O
universal	O
protocol	O
,	O
it	O
is	O
often	O
assumed	O
that	O
there	O
is	O
no	O
longer	O
any	O
need	O
for	O
FEPs	O
,	O
which	O
traditionally	O
handled	O
SNA	B-Architecture
traffic	O
.	O
</s>
<s>
This	O
may	O
be	O
true	O
where	O
FEPs	O
provide	O
only	O
straight	O
connectivity	O
(	O
and	O
assuming	O
IP	B-Protocol
address	O
never	O
changes	O
)	O
.	O
</s>
<s>
However	O
,	O
FEPs	O
also	O
perform	O
other	O
vital	O
functions	O
,	O
that	O
are	O
closely	O
linked	O
to	O
transaction	O
applications	O
,	O
including	O
message	O
and	O
transaction	O
switching	O
,	O
multiplexing	B-Architecture
,	O
transaction	O
security	O
,	O
quality	O
of	O
service	O
guarantors	O
,	O
and	O
end-to-end	O
transaction	O
management	O
and	O
reporting	O
.	O
</s>
<s>
Although	O
the	O
IBM	O
Corporation	O
withdrew	O
its	O
3745/3746	B-Device
Communications	O
Front	B-Application
End	I-Application
Processors	I-Application
from	O
marketing	O
in	O
2003	O
,	O
the	O
company	O
continues	O
to	O
maintain	O
the	O
estimated	O
20,000	O
installed	O
front-end	B-Application
processors	I-Application
.	O
</s>
