FTP i-to-i part 2

Having gone through a lot of the basics of using FTP, File Transfer Protocol, on an IBM i in the post FTP i-to-i part 1, in this post I will describe how I can transfer physical files, using FTP, to another instance of IBM i, whether it be another partition or another server.

In this scenario I have a job on QSRV1 that generates physical files that need to be transferred to QSRV2 to be processed. If this was a real job I would automate the FTP transfer, I will explain how to do it in Part 3. But in this post I am going describe how I would do it manually, one FTP subcommand at a time.

The physical files I am going to transfer from QSRV1 all start with "FTP" followed by a unique sequence number, for example: FTP00129, and are found in the library FTPOUT. I will be copying these files to the library FTPIN on QSRV2, and I will be calling a program to process the on QSRV2.

As I could be transferring more than one file I am going to use two FTP subcommands that I did not mention in my previous post:

• mput - Mass copy of file(s) from the FTP client to the FTP host.
• mget - Mass copy of file(s) from the FTP host to the FTP client.

The first thing I need to do is start FTP on QSRV1 using the FTP command:

ftp qsrv2

When the FTP entry screen opens it looks like:

File Transfer Protocol Previous FTP subcommands and messages: Connecting to remote host 173.194.117.192 using port 21. 220-QTCP at qsrv2. 220 Connection will close if idle more than 5 minutes. Enter login ID (simonh): ===> _____________________________________________________ ___________________________________________________________ ___________________________________________________________ F3=Exit F6=Print F9=Retrieve F17=Top F18=Bottom F21=CL command line

I enter my login id, user profile on QSRV2, and password. I am not going to bother to show you the message for those as you have seen them in Part 1.

I use the lcd to change the default directory/library FTP will use on QSRV1.

lcd ftpout

Which produces the following in the message section of the screen:

> lcd ftpout Local working directory is FTPOUT

Then I change the default directory/library FTP will using on QSRV2 using cd.

cd ftpin

I can see if this was successful by viewing the message section of the screen:

> cd ftpin 250 "FTPIN" is current library.

Now comes the new FTP subcommand mput to copy the files from the FTP client, QSRV1, to the FTP host, QSRV2. The mput allows me to copy with a wildcard, therefore to copy all the files all I need to enter is:

mput ftp*

As the files are copied the message section is updated with each file copied:

227 Entering Passive Mode (173,194,117,192). 150 Sending file to member FTP00129 in file FTP00129 in library FTPOUT. 226 File transfer completed successfully. 37 bytes transferred in 0.053 seconds. Transfer rate 0.702 KB/sec. 227 Entering Passive Mode (173,194,117,192). 150 Sending file to member FTP00130 in file FTP00130 in library FTPOUT. 226 File transfer completed successfully. 82 bytes transferred in 0.020 seconds. Transfer rate 4.198 KB/sec. 227 Entering Passive Mode (173,194,117,192). 150 Sending file to member FTP00131 in file FTP00131 in library FTPOUT. 226 File transfer completed successfully. 1280 bytes transferred in 0.016 seconds. Transfer rate 81.920 KB/sec.

I can see that all three of the files were copied to QSRV2. This does not remove them from FTPOUT, from which they will need to be deleted so that they will not be copied again.

When the files are copied they become "flat files", files that do not contain the fields they did on the FTP client. For example, FTP0129 on QSRV1 looks like this when I use the RUNQRY to view its contents:

Line ....+....1....+....2....+.... First Second Third field field field 000001 1 1 one 000002 2 2 two 000003 3 3 three----> ****** ******** End of report ********

The copied version of the file on FTP host, QSRV2, does not have individual fields. This is the same file on QSRV2 when I use RUNQRY:>

Line ....+....1....+ FTP00129 000001 1 one 000002 2 000003 3 three----> ****** ******** End of report ********

This is easily solved by using the CPYF command to copy the "flat file" to another with the desired fields. The FMTOPT(*NCOCHK) means that the data in each record is copied from left to right into the to file regardless of field type. Therefore, the to file should be identical to the file that the data was copied from on QSRV1.

CPYF FROMFILE(FTPIN/FTP0129) TOFILE(MYLIB/FTPFILE1) + MBROPT(*ADD) FMTOPT(*NOCHK)

After going off on the tangent about the format of the copied file on QSRV2 let me return to the FTP. Having copied the files now I need to call the program to process them. This I can do using the quote FTP subcommand.

quote rcmd CALL MYLIB/PGM1

When the program finishes you will see the following in the message section:

> quote rcmd call mylib/pgm1 250 Command call mylib/pgm1 successful.

Personally I would not recommend calling a program, I would submit a job so that the FTP can be ended without having to wait for the called program to end.

In Part 3 I will discuss how to automate this.

 

Other posts in this series:

• FTP i-to-i part 1: Introduction and sending save files via FTP
• FTP i-to-i part 3: Creating a FTP program

 

You can learn more about this on IBM's website:

• FTP subcommands
• CPYF command FMTOPT parameter

 

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Addendum

Sorry guys I forgot the problem with FTP-ing files with packed fields. There is some combination of hexadecimal codes in packed fields that is misinterpreted by the FTP process as a CR (Carriage Return) or LF (Line Feed), which causes an additional record to appear. You know, 10 records in the file on QSRV1 and 11 in the file on QSRV2.

The way to prevent this is to code all numeric fields as signed numeric. What I have done in the past is either to change the packed fields in the file to be FTP-ed to signed, or I would a create a work file that is identical to the original file and used REF in the DDS to make the new work file identical to the original, apart from the packed field that I reassign as signed. The code below shows that:

A REF(FTP001P) A R FTP001WR A FLD001 R A FLD002 R S A FLD003 R A FLD004 R S A FLD005 R S A FLD006 R S A FLD007 R A FLD008 R

Fields FLD002, FLD004, FLD005, and FLD006 are all packed fields in the original file, FTP001P, and are redefined as signed in the work file, FTP001W.

The data from FTP001P can be copied using CPYF into FTP001W and the data in the packed fields will be converted to signed.

CPYF FROMFILE(FTP001P) TOFILE(FTP001W) MBROPT(*REPLACE) FMTOPT(*MAP)

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This article was written for IBM i 7.1.