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Discussions > FAST Protocol > Identify Frame lenght in FAST UDP packet

Identify Frame lenght in FAST UDP packet

Complete message thread from old site

Himanshu K
807 days ago,(2012/02/07)

Hi

I am receiving UDP packet in following manner

|frame size(1)|msg(1)|frame size2|msg(2)|...|frame size(i)|msg(i)|
=================================================================
UDP PACKET N

How to identify frame length so that I can find size of msg(1)...consequently of msg(2)......msg(3)....

Frame size usually the first byte but it can be up to 4 bytes of uncompressed data received.How to identify when it's more than 1 byte?

Thanks

Himanshu

FIX Trading Community
806 days ago,(2012/02/08)

[ original email was from janaka Sooriyaarachchi - janakas@millenniumit.com ]

frame size also a integer value, So you can use integer encoding/ decoding method to resolve the value and you can identify the field termination by stop bit.

> Hi
>
> I am receiving UDP packet in following manner
>
> |frame size(1)|msg(1)|frame size2|msg(2)|...|frame size(i)|msg(i)|
> =================================================================
> UDP PACKET N
>
> How to identify frame length so that I can find size of msg(1)...consequently of msg(2)......msg(3)....
>
> Frame size usually the first byte but it can be up to 4 bytes of uncompressed data received.How to identify when it's more than 1 byte?
>
> Thanks
>
> Himanshu

Himanshu K
806 days ago,(2012/02/08)

Hi Janaka

Binary feeds received have following value in first four bytes.
What will be stop bit here to find message length here ?

case 1.

Uncompressed binary data received

F1 DE 00 83
11110001 11011110 00000000 10000011

Removing first bit and converting to integer value

1110001 11011110 - 0000011

Integer Value

113 94 3

************************************************************************

Case 2

Uncompressed binary data received

01 8B DE 00
00000001 10001011 11011110 00000000

Removing first bit and converting to integer value

- 0001011 1011110 -

Integer Value

- 11 94 -

> frame size also a integer value, So you can use integer encoding/ decoding method to resolve the value and you can identify the field termination by stop bit.
>
>
> > Hi
> >
> > I am receiving UDP packet in following manner
> >
> > |frame size(1)|msg(1)|frame size2|msg(2)|...|frame size(i)|msg(i)|
> > =================================================================
> > UDP PACKET N
> >
> > How to identify frame length so that I can find size of msg(1)...consequently of msg(2)......msg(3)....
> >
> > Frame size usually the first byte but it can be up to 4 bytes of uncompressed data received.How to identify when it's more than 1 byte?
> >
> > Thanks
> >
> > Himanshu

FIX Trading Community
805 days ago,(2012/02/09)

[ original email was from janaka Sooriyaarachchi - janakas@millenniumit.com ]
Hi,

In the Case 1,
Very first bit also have a stop bit.
So your message length is 113. That contains in a single byte

But in case 2,
you need to take 2 bytes,

00000001 10001011

After removing stop bits,
0000001 0001011

Then convert that value to decimal
00000010001011 = 139

now your message length is 139.

> Hi Janaka
>
> Binary feeds received have following value in first four bytes.
> What will be stop bit here to find message length here ?
>
> case 1.
>
> Uncompressed binary data received
>
> F1 DE 00 83
> 11110001 11011110 00000000 10000011
>
>
>
> Removing first bit and converting to integer value
>
> 1110001 11011110 - 0000011
>
> Integer Value
>
> 113 94 3
>
> ************************************************************************
>
>
> Case 2
>
> Uncompressed binary data received
>
>
> 01 8B DE 00
> 00000001 10001011 11011110 00000000
>
>
> Removing first bit and converting to integer value
>
> - 0001011 1011110 -
>
> Integer Value
>
> - 11 94 -
>
>
>
>
>
>
>
>
>
>
>
>
> > frame size also a integer value, So you can use integer encoding/ decoding method to resolve the value and you can identify the field termination by stop bit.
> >
> >
> > > Hi
> > >
> > > I am receiving UDP packet in following manner
> > >
> > > |frame size(1)|msg(1)|frame size2|msg(2)|...|frame size(i)|msg(i)|
> > > =================================================================
> > > UDP PACKET N
> > >
> > > How to identify frame length so that I can find size of msg(1)...consequently of msg(2)......msg(3)....
> > >
> > > Frame size usually the first byte but it can be up to 4 bytes of uncompressed data received.How to identify when it's more than 1 byte?
> > >
> > > Thanks
> > >
> > > Himanshu

Himanshu K
805 days ago,(2012/02/09)

It's working now...

Thanks Janaka for valuable help..:)

> Hi,
>
> In the Case 1,
> Very first bit also have a stop bit.
> So your message length is 113. That contains in a single byte
>
> But in case 2,
> you need to take 2 bytes,
>
> 00000001 10001011
>
> After removing stop bits,
> 0000001 0001011
>
> Then convert that value to decimal
> 00000010001011 = 139
>
> now your message length is 139.
>
>
>
>
> > Hi Janaka
> >
> > Binary feeds received have following value in first four bytes.
> > What will be stop bit here to find message length here ?
> >
> > case 1.
> >
> > Uncompressed binary data received
> >
> > F1 DE 00 83
> > 11110001 11011110 00000000 10000011
> >
> >
> >
> > Removing first bit and converting to integer value
> >
> > 1110001 11011110 - 0000011
> >
> > Integer Value
> >
> > 113 94 3
> >
> > ************************************************************************
> >
> >
> > Case 2
> >
> > Uncompressed binary data received
> >
> >
> > 01 8B DE 00
> > 00000001 10001011 11011110 00000000
> >
> >
> > Removing first bit and converting to integer value
> >
> > - 0001011 1011110 -
> >
> > Integer Value
> >
> > - 11 94 -
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > frame size also a integer value, So you can use integer encoding/ decoding method to resolve the value and you can identify the field termination by stop bit.
> > >
> > >
> > > > Hi
> > > >
> > > > I am receiving UDP packet in following manner
> > > >
> > > > |frame size(1)|msg(1)|frame size2|msg(2)|...|frame size(i)|msg(i)|
> > > > =================================================================
> > > > UDP PACKET N
> > > >
> > > > How to identify frame length so that I can find size of msg(1)...consequently of msg(2)......msg(3)....
> > > >
> > > > Frame size usually the first byte but it can be up to 4 bytes of uncompressed data received.How to identify when it's more than 1 byte?
> > > >
> > > > Thanks
> > > >
> > > > Himanshu