FTP client API messages and replies

Messages are information statements that are provided by the FTP client. Replies are the responses to commands that are returned from the FTP server to the client. Replies are described in FTPD reply codes in z/OS Communications Server: IP and SNA Codes.

Messages are composed of a message ID followed by message text. FTP client messages are described in z/OS Communications Server: IP Messages Volume 1 (EZA) and z/OS Communications Server: IP Messages Volume 4 (EZZ, SNM). You can use the message ID to look up the message in these volumes. However, the message IDs are not written to output unless the client is executing in verbose mode.

Following is an example that uses the verbose subcommand in an interactive environment. The FTP client API processes the subcommand on an SCMD request as previously described. Note that the verbose subcommand acts as a toggle.

verbose
EZA2859I Message IDs are displayed when running in z/OS UNIX
EZA1460I Command:
verbose
Message IDs are not displayed when running in z/OS UNIX
Command:

EZA2859I and EZA1460I (the first token that is displayed when executing in verbose mode) are message IDs. The phrases that follow the message ID are message text. Notice that after the verbose command is executed the second time to toggle verbose off, the message texts appear with no message ID. See the Verbose subcommand information in z/OS Communications Server: IP User's Guide and Commands for more information about entering and exiting verbose mode.

The FTP client API does not use the EZA1460I Command: message. Instead, it uses a new message with additional status information about the subcommand that completed. The syntax is:

EZA2121I Command (ee-ss-cccc-rrr):

where:

ee is the 2-digit decimal client error code for the subcommand (00 if no error)
ss is the 2-digit decimal subcommand code (the field is blank on INIT when an implicit OPEN was not performed)
cccc is the final 4-character FTP command sent to the server by the subcommand (all blanks if no command was sent)
rrr is the last 3-character server reply to the final FTP command (all blanks if no reply was received)

Replies are composed of a 3-digit numeric reply code followed by text. The significance of the reply prefix is described in RFC 959, File Transfer Protocol (see Related protocol specifications for information about accessing RFCs); replies used by the z/OS® FTP server are described in FTPD reply codes in z/OS Communications Server: IP and SNA Codes. Unlike message numbers, reply codes are never suppressed. Your program can usually disregard the text and inspect the reply code to determine whether the server processed the FTP command successfully. The one exception is when an FTP client sends the SITE command to a z/OS FTP server. The z/OS FTP server SITE reply is always 200 (implying success), even when one or more errors occurred when processing the SITE command, as in the following example:

site bogus
>>> SITE bogus
200-Unrecognized parameter 'bogus' on SITE command.
200 SITE command was accepted
Command(00-34-SITE-200):

The following sample output from the CD subcommand shows messages EZA1701I and EZA2121I from the FTP client and the reply 250 from the FTP server. Note that the CD subcommand causes the client to send the CWD command to the server.

CD  /u/user33/
EZA1701I >>> CWD /u/user33/
250 HFS directory /u/user33/ is the current working directory
EZA2121I Command(00-07-CWD -250):
verbose
Message IDs are not displayed when running in z/OS UNIX
Command(00-71-    -   ):
CD  /u/user33/
>>> CWD /u/user33/
250 HFS directory /u/user33/ is the current working directory
Command(00-07-CWD -250):