Just another tidbit, but when combining the record segments, while
the VBS architecture does not specify a maximum record length, you
can expect the full records to be up to 16,777,215 (16384K - 1) bytes
in length.
Realizing that the RDW is actually a SDW.
Michael
At 01:26 AM 5/16/2023, Michael Stein wrote:
On Tue, May 16, 2023 at 04:14:07AM +0000, Prashant Joshi wrote:
>> Did you specify binary mode on the python open call? --
> Yes. And I can read the data.
How are you reading the data. Assuming an open like:
myfile = open("filename", "rb")
You need to either read it all into memory:
alldata = myfile.read()
or read specific lengths which is messier as you need to read specific
lengths, first 4 bytes for the RDW and then the length of the record
in the RDW-4 (as you already read the RDW).
The 4 byte RDW includes the length of the record in the first 2 bytes
(bigendian order) and the spanning bits in the last 2 bytes.
Either way you need to walk your way through the binary data, any code
looking for CR or NL or space isn't correct.
A description of VBS records formats:
z/OS 2.4 DFSMS Using Data Sets SC23-6855-40
https://www-40.ibm.com/servers/resourcelink/svc00100.nsf/pages/zOSV2R4sc236855/$file/idad400_v2r4.pdf
pdf page 273 Variable-Length Record Formats
(near bottom of page and continues on to more pages)
> its just that I don't get proper end of reord. Hence every time I
> read record, I get random record length (multiple records/half records
> combined)
There aren't any "end of records" in a VBS file. At the begining of
the file you know you are at the start of a RDW (Well, BDW/RDW but I'm
assuming the FTP removed the BDWs).
You can find the next record by going the length specified in the RDW
into the file -- that is the start of the next RDW. Continue until
you've processed all the records.
More help will likely require you to show some code and/or data so
we can see what is going on...
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