[Cosmic_announce] Change in BUFR file header

[Doug Hunt]

Sean:  We can hold off on the changes if you'd like.  I thought this was a 
small header change which would not affect users.  We'll start with the 
new files (say) next Tuesday.

I'll send you a sample file as soon as I'm sure I've got the right format.
Some time today.

--Doug

dhunt at ucar.edu
Software Engineer III
UCAR - COSMIC, Tel. (303) 497-2611

On Fri, 12 Jan 2007, Sean Healy wrote:

> Hi Doug,
>
> I am unclear whether this change will be made to the bufr files we currently 
> get via ftp from UCAR or are they changes to a new, parallel data stream?
>
> Do you really have to make the changes on a Friday? Could
> we not see a few sample files first, and then make the changes
> next week?
>
> Thanks
>
> Sean.
>
>
>
>
>
>
>
>
>
> Doug Hunt wrote:
>> Hi all:  In order to get cosmic BUFR files (bfrPrf) on the GTS, we need to 
>> make a small change to the header bytes at the beginning of the bfrPrf 
>> files.
>> 
>> Currently, the header of a "WMO message" is being sent, which starts with:
>> 
>> 00000000: 010d 0d0a 2d2d 2d0d 0d0a 4955 5446 3134  ....---...IUTF14
>> 00000010: 204b 5742 4320 3131 3030 3131 0d0d 0a42   KWBC 110011...B
>> 00000020: 5546 5200 2104 0300 0012 0000 3c00 0003  UFR.!.......<...
>> 
>> In order to get the NESDIS DDS system to accept these files,
>> they need to have the WMO starting line:
>> 
>> [SOH][cr][cr][lf]nnn  Where nnn is 0-999 sequence number
>> 
>> replaced by a 'Flag Field Separator':
>> 
>> ####018008476####[lf]
>> 
>> where 018 is the flag field separator length and 008476 is the BUFR message 
>> length.
>> 
>> So, the new files will start like this:
>> 
>> 00000000: 2323 2323 3031 3830 3038 3437 3623 2323  ####018008476###
>> 00000010: 230a 0d0d 0a49 5554 4a31 3420 4b57 4243  #....IUTJ14 KWBC
>> 00000020: 2031 3032 3335 390d 0d0a 4255 4652 0021   102359...BUFR.!
>> 
>> My understanding is that any good BUFR decoder will skip past
>> these initial bytes.
>> 
>> The new files will have a 0001.0006_bufr suffix.  They will start being 
>> produced tomorrow.
>> 
>> Regards,
>>
>>   Doug Hunt
>> 
>> dhunt at ucar.edu
>> Software Engineer III
>> UCAR - COSMIC, Tel. (303) 497-2611
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>