A good philosophy is to use some program common to both sending and receiving systems that will compress and possibly encrypt the data, retaining the file's original record formatting as part of the new data file. Transfer that new data file and decrypt/expand it at the receiving site. XMIT can be used to simply reblock the data to retain record formatting, TERSE/DETERSE can be used to compress and reblock. PKZIP can also be used. If you have a mainframe based data encryption product, it might have its own compress&encrypt utility, if you can convince the receiving system to use the same product.
/Tom Kern On Wed, 9 Jan 2008 15:24:32 -0600, Bruce Baxter <[EMAIL PROTECTED]> wrote: >We've routinely exhanged files with business partners running on z/OS >machines using tape for years. > >We're now in the process of converting a number of these to electronic >means, using in part FTP. This is being done at the behest of one of our >business partners, who (IMHO) hasn't thought through all the issues that the >use of FTP introduces in this process. The central issue as I see it is that the >mainframes at either end of the pipeline are both EBCDIC and record oriented, >and the servers and ftp processes that lie between them to facilitate these >transfers do not have any inherent concept of record oriented files like the >mainframe. > >I'm going to treat FIXED BLOCK data separately from VARIABLE BLOCKED data >separately. > >The first files that we received were FIXED BLOCK, and had been translated >from EBCDIC to ASCII, most likely at the first transfer of the file from z/OS to >an ASCII based server platform (either Windows or AIX). When they arrived >on our z/OS system, we had issues of data corruption because the data >contained zoned decimal data. After some discussion, we agreed that we'd >transfer these files in BINARY mode at all steps along the way. Thus, all we >had to do was ensure that the LRECL used for the destination dataset on >z/OS was the same as the source dataset. This seems to be working OK. > >Most recently, we've been having problems with other files that are VARIABLE >BLOCKED. We received the first of these files last week, transmitted from end- >to-end in BINARY mode. What we got was not at all what we expected. >We've discovered that the initial FTP from z/OS to the server stripped off all >information regarding record length and thus record delineation. Because >there aren't any RDWs in front of every record, ftp doesn't know how long the >records are and just plunks the data into the destination dataset in chunks of >LRECL-4. I did a bunch of research on z/OS FTP and there doesn't appear to >be any way to make it convey record length/delineation information to and >ASCII platform other than to use ASCII mode. z/OS FTP appears to have >mechanisms for conveying this between two z/OS FTP systems, but that's not >possible here. For the present time, we've had the file shipped with the initiatl >movement translating the data from EBCDIC to ASCII and all subsequent >transfers until the last one back to z/OS in BINARY mode. However, I'm >concerned about the possibility of data corruption if the translate tables used >in the first step and the last step of this files travel aren't exact inversions of >each other. This would certainly be possible of the initial ASCII transfer were >done to a Windows Code Page 1252 system and the last transfer (having >CP1252 data) were translating between UTF-8 and CP037. > >I'm interested in other folks war stories and what they've implemented for best >practices. I've made clear to our developers and end-users that ftp is >certainly not a direct replacement for tape transfers. It would appear that we >need lots of information about all the systems and transformations done in >moving the file from one system to another. FTP doesn't convey this sort of >information in any way shape or form. > >What sort of options are there? > >- Transmit/Receive would certainly be one, but would add a lot of overhead to >the process. >- Removal of all non-display data from the files and subjecting them to ASCII >translation at every step would also be an option, but that would likely be >rejected by our business partner as too much work. >- Are there any options to z/OS FTP that would allow record formatting >information to be conveyed in the file, if we presume that we'd transfer it in >binary mode at every step. > >Has anyone come across any clear helpful best practice type information or >sites? I'd be interested in anything anyone has. > >Regards, >Bruce Baxter >Manager of DP Tech Services >NYS Dept of Tax and Finance. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
