<s>
The	O
Financial	B-Protocol
Information	I-Protocol
eXchange	I-Protocol
(	O
FIX	O
)	O
protocol	O
is	O
an	O
electronic	O
communications	O
protocol	O
initiated	O
in	O
1992	O
for	O
international	O
real-time	O
exchange	O
of	O
information	O
related	O
to	O
securities	O
transactions	O
and	O
markets	O
.	O
</s>
<s>
Managing	O
the	O
delivery	O
of	O
trading	O
applications	O
and	O
keeping	O
latency	O
low	O
increasingly	O
requires	O
an	O
understanding	O
of	O
the	O
FIX	B-Protocol
protocol	I-Protocol
.	O
</s>
<s>
The	O
FIX	B-Protocol
protocol	I-Protocol
specification	O
was	O
originally	O
authored	O
in	O
1992	O
by	O
Robert	O
"	O
Bob	O
"	O
Lamoureux	O
and	O
Chris	O
Morstatt	O
to	O
enable	O
electronic	O
communication	O
of	O
equity	O
trading	O
data	O
between	O
Fidelity	O
Investments	O
and	O
Salomon	O
Brothers	O
.	O
</s>
<s>
It	O
wanted	O
such	O
communications	O
to	O
be	O
replaced	O
with	O
machine-readable	B-General_Concept
data	I-General_Concept
which	O
could	O
then	O
be	O
shared	O
among	O
traders	O
,	O
analyzed	O
,	O
acted	O
on	O
and	O
stored	O
.	O
</s>
<s>
The	O
is	O
a	O
non-profit	O
,	O
industry-driven	O
standards	O
body	O
with	O
a	O
mission	O
to	O
address	O
the	O
business	O
and	O
regulatory	O
issues	O
impacting	O
multi-asset	O
trading	O
across	O
the	O
global	O
financial	O
markets	O
through	O
the	O
increased	O
use	O
of	O
standards	O
,	O
including	O
the	O
FIX	B-Protocol
Protocol	I-Protocol
messaging	O
language	O
,	O
delivering	O
operational	O
efficiency	O
,	O
increased	O
transparency	O
,	O
and	O
reduced	O
costs	O
and	O
risk	O
for	O
all	O
market	O
participants	O
.	O
</s>
<s>
One	O
could	O
say	O
that	O
whereas	O
SWIFT	B-Language
is	O
the	O
standard	O
for	O
back	O
office	O
messaging	O
,	O
FIX	O
is	O
the	O
standard	O
for	O
front	O
office	O
messaging	O
.	O
</s>
<s>
However	O
,	O
today	O
,	O
the	O
membership	O
of	O
FIX	B-Protocol
Protocol	I-Protocol
Ltd	O
.	O
is	O
extending	O
FIX	O
into	O
block	O
trade	O
allocation	O
and	O
other	O
phases	O
of	O
the	O
trading	O
process	O
,	O
in	O
every	O
market	O
,	O
for	O
virtually	O
every	O
asset	O
class	O
.	O
</s>
<s>
Message	O
encoding	O
,	O
called	O
Presentation	B-Application
Layer	I-Application
in	O
the	O
Open	O
Systems	O
Interconnection	O
model	O
(	O
OSI	O
model	O
)	O
,	O
is	O
responsible	O
for	O
the	O
wire	O
format	O
of	O
messages	O
.	O
</s>
<s>
Tagvalue	O
encoding	O
is	O
character-based	O
,	O
using	O
ASCII	B-Protocol
codes	I-Protocol
.	O
</s>
<s>
The	O
message	O
fields	O
are	O
delimited	O
using	O
the	O
ASCII	B-Protocol
01	O
<start of header>	O
character	O
.	O
</s>
<s>
From	O
FIXT.1.1	O
/	O
FIX.5.0	O
,	O
the	O
header	O
contains	O
five	O
mandatory	O
fields	O
and	O
one	O
optional	O
field	O
:	O
8	O
(	O
BeginString	O
)	O
,	O
9	O
(	O
BodyLength	O
)	O
,	O
35	O
(	O
MsgType	O
)	O
,	O
49	O
(	O
SenderCompID	O
)	O
,	O
56	O
(	O
TargetCompID	O
)	O
and	O
1128	O
(	O
ApplVerID	O
-	O
if	O
present	O
must	O
be	O
in	O
6th	O
position	O
)	O
.	O
</s>
<s>
The	O
last	O
field	O
of	O
the	O
message	O
is	O
tag	O
10	O
,	O
FIX	O
Message	O
Checksum	B-Algorithm
.	O
</s>
<s>
In	O
the	O
above	O
FIXMessage	O
Body	O
length	O
9	O
is	O
correct	O
and	O
checksum	B-Algorithm
10	O
was	O
checked	O
out	O
by	O
using	O
the	O
source	O
available	O
from	O
QuickFIX	B-Operating_System
,	O
an	O
open-source	O
FIX	O
implementation	O
.	O
</s>
<s>
The	O
FIX	B-Protocol
protocol	I-Protocol
defines	O
meanings	O
for	O
most	O
tags	O
,	O
but	O
leaves	O
a	O
range	O
of	O
tags	O
reserved	O
for	O
private	O
use	O
between	O
consenting	O
parties	O
.	O
</s>
<s>
The	O
FIX	B-Protocol
protocol	I-Protocol
also	O
defines	O
sets	O
of	O
fields	O
that	O
make	O
a	O
particular	O
message	O
;	O
within	O
the	O
set	O
of	O
fields	O
,	O
some	O
will	O
be	O
mandatory	O
and	O
others	O
optional	O
.	O
</s>
<s>
The	O
final	O
field	O
in	O
any	O
FIX	O
message	O
is	O
tag	O
10	O
(	O
checksum	B-Algorithm
)	O
.	O
</s>
<s>
The	O
checksum	B-Algorithm
of	O
a	O
FIX	O
message	O
is	O
always	O
the	O
last	O
field	O
in	O
the	O
message	O
.	O
</s>
<s>
It	O
is	O
given	O
by	O
summing	O
the	O
ASCII	B-Protocol
value	I-Protocol
of	O
all	O
characters	O
in	O
the	O
message	O
,	O
except	O
for	O
those	O
of	O
the	O
checksum	B-Algorithm
field	O
itself	O
,	O
and	O
performing	O
modulo	O
256	O
over	O
the	O
resulting	O
summation	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
message	O
above	O
,	O
the	O
summation	O
of	O
all	O
ASCII	B-Protocol
values	I-Protocol
(	O
including	O
the	O
SOH	O
character	O
,	O
which	O
has	O
a	O
value	O
of	O
1	O
in	O
the	O
ASCII	B-Protocol
table	O
)	O
results	O
in	O
4158	O
.	O
</s>
<s>
Since	O
the	O
checksum	B-Algorithm
is	O
composed	O
of	O
three	O
characters	O
,	O
062	O
is	O
used	O
.	O
</s>
<s>
FIXML	B-Protocol
is	O
an	O
XML	O
schema	O
for	O
FIX	O
messages	O
.	O
</s>
<s>
FIXML	B-Protocol
is	O
commonly	O
used	O
for	O
back-office	O
and	O
clearing	O
applications	O
rather	O
than	O
trading	O
.	O
</s>
<s>
Unlike	O
tagvalue	O
and	O
FIXML	B-Protocol
,	O
an	O
SBE	O
message	O
is	O
not	O
self-describing	O
.	O
</s>
<s>
However	O
,	O
starting	O
with	O
FIX	O
version	O
5.0	O
,	O
the	O
session	O
layer	O
was	O
split	O
off	O
as	O
an	O
independent	O
specification	O
with	O
the	O
introduction	O
of	O
FIXT	B-Protocol
.	O
</s>
<s>
FIXT	B-Protocol
was	O
largely	O
the	O
same	O
as	O
the	O
original	O
unnamed	O
session	O
layer	O
in	O
version	O
4.x	O
,	O
but	O
it	O
offered	O
one	O
significant	O
innovation--it	O
provided	O
a	O
mechanism	O
to	O
mix	O
FIX	O
application	O
layer	O
versions	O
over	O
a	O
common	O
session	O
version	O
.	O
</s>
<s>
The	O
current	O
FIXT	B-Protocol
version	O
is	O
1.1	O
.	O
</s>
<s>
Theoretically	O
,	O
FIXT	B-Protocol
is	O
transport	O
independent	O
.	O
</s>
<s>
However	O
,	O
it	O
is	O
usually	O
employed	O
over	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
TCP	O
)	O
.	O
</s>
<s>
FIXT	B-Protocol
is	O
a	O
point-to-point	O
protocol	O
.	O
</s>
<s>
Messages	O
sent	O
in	O
each	O
direction	O
carry	O
a	O
message	O
sequence	B-Protocol
number	I-Protocol
in	O
the	O
message	O
header	O
.	O
</s>
<s>
To	O
implement	O
session	O
establishment	O
and	O
guaranteed	O
delivery	O
,	O
FIXT	B-Protocol
and	O
classic	O
FIX	O
4.x	O
define	O
these	O
session	O
message	O
types	O
:	O
</s>
<s>
In	O
fast	B-Protocol
moving	O
markets	O
,	O
the	O
delay	O
inherent	O
in	O
retransmission	O
is	O
often	O
undesirable	O
,	O
resulting	O
in	O
missed	O
opportunities	O
or	O
bad	O
trades	O
.	O
</s>
<s>
The	O
latest	O
version	O
of	O
FIX	B-Protocol
Protocol	I-Protocol
implements	O
"	O
Transport	O
Independence	O
"	O
by	O
permitting	O
multiple	O
versions	O
of	O
application	O
messages	O
to	O
be	O
carried	O
over	O
a	O
single	O
version	O
of	O
Transport	O
Independent	O
FIX	O
Session	O
(	O
FIXT.1.1	O
and	O
higher	O
)	O
.	O
</s>
<s>
Transport	O
Independence	O
also	O
paves	O
the	O
way	O
for	O
transport	O
protocols	O
such	O
as	O
message	B-Operating_System
queues	I-Operating_System
and	O
web	O
services	O
to	O
be	O
used	O
instead	O
of	O
traditional	O
FIX	O
over	O
TCP	O
.	O
</s>
<s>
FIX	O
now	O
supports	O
algorithmic	O
trading	O
by	O
the	O
use	O
of	O
FIX	B-Algorithm
Algorithmic	I-Algorithm
Trading	I-Algorithm
Definition	I-Algorithm
Language	I-Algorithm
FIXatdl	B-Algorithm
.	O
</s>
<s>
In	O
2005	O
,	O
the	O
FIX	O
Trading	O
Community	O
released	O
FAST	B-Protocol
protocol	I-Protocol
which	O
stands	O
for	O
FIX	O
Adapted	O
for	O
Streaming	O
.	O
</s>
<s>
FAST	B-Protocol
is	O
a	O
binary	O
protocol	O
and	O
is	O
used	O
mostly	O
for	O
sending	O
Multicast	O
market	O
data	O
via	O
UDP	O
connections	O
.	O
</s>
<s>
Further	O
,	O
in	O
2020	O
,	O
the	O
FIX	O
Trading	O
Community	O
a	O
new	O
FIX	O
binary	O
encoding	O
,	O
based	O
on	O
Simple	O
Binary	O
Encoding	O
(	O
SBE	O
)	O
,	O
meant	O
to	O
complement	O
the	O
existing	O
FAST	B-Protocol
encoding	O
.	O
</s>
