An iSeries Network Publication           
http://www.iSeriesNetwork.com
Home of iSeries NEWS Magazine                    
Editor: Scott Klement
Issue 198                                               
March 10, 2005

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EDITOR'S NOTE:

I will be at COMMON in Chicago next week. If you'll be there and 
happen to see me, please come over and say "hi." It's always good to 
hear from my readers!

 -- Scott Klement, Club Tech iSeries Programming Tips Editor

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THIS WEEK: 
> Launch Commands Longer than 123 Characters on the PC
> Base64 Encode/Decode Utility
Pro and Pro VIP Edition Items: 
> Open Source SOAP with Axis
> Consistent Error Handling Part 2: Using a *PSSR in a Subprocedure

1. LAUNCH COMMANDS LONGER THAN 123 CHARACTERS ON THE PC
Q: STRPCCMD does a fine job of running programs on my PC from the iSeries. 
However, the command string can only be 123 characters long. That's not 
enough! How can I open a Word document that's located in a huge directory 
structure?

A: The venerable STRPCCMD command has been around for a long time. When it 
was first made available, 123 characters was usually long enough. Now, it's 
definitely not. Here are some suggestions for overcoming this limitation:

CREATE A BATCH FILE
You could create a batch file on the PC that contains the longer name and 
then execute that batch file with STRPCCMD. It's even possible to create the 
batch file on the fly.

For example, you can use STRPCCMD to create a batch file called MYFILE.BAT 
in the C:\DATA directory. You create it using the MS-DOS echo command to 
write data to a file on disk. The following sample code uses this technique 
to launch a long-named Word document:
STRPCCMD PCCMD('cmd /c ECHO SET MYDOC=c:\documents and settings> +
                C:\DATA\MYFILE.BAT')
STRPCCMD PCCMD('cmd /c ECHO SET MYDOC=%MYDOC%\alexander.acctdom\my +
                documents>> C:\DATA\MYFILE.BAT')
STRPCCMD PCCMD('cmd /c ECHO SET MYDOC=%MYDOC%\weekly\credit memos\acme +
                inc>> C:\DATA\MYFILE.BAT')
STRPCCMD PCCMD('cmd /c ECHO SET MYDOC=%MYDOC%\memo84612.doc>> +
                C:\DATA\MYFILE.BAT')
STRPCCMD PCCMD('cmd /c ECHO start "%MYDOC%">> C:\DATA\MYFILE.BAT')
STRPCCMD PCCMD('C:\DATA\MYFILE.BAT')

The idea for this technique came from a message posted to the iSeries 
Network forums by Herman Van der Staey. Thanks, Herman!

USE RUNRMTCMD INSTEAD
Another problem with STRPCCMD, aside from the length limitation, is 
that it relies on 5250 emulation from iSeries Access in order to 
determine which computer to connect to and which user to run the 
commands as. Not everyone uses iSeries Access. In fact, not everyone 
runs Windows!

Another IBM-supplied way to run commands on another computer is the 
RUNRMTCMD command. This allows up to 2000 characters to be specified 
for the command to run on the PC. When used over TCP/IP, it uses the 
RExec protocol that's widely used on other platforms as well. You're 
not limited to Windows!

To use this command, you first need to run an incoming remote command 
service on the PC. If you're running Windows, there's a free RExec 
service available in iSeries Access that you can install. Once 
installed, it needs to be enabled under "Services" in the control 
panel. It will be called "iSeries Incoming Remote Command" or 
something similar. If you want to do things like open Word documents 
or Web browsers, make certain that you go into the properties of the 
service and check the "Allow programs to interact with the desktop" 
checkbox.

If you don't have iSeries Access, or don't want to use it, search the 
Internet for an RExec server for Windows. There are several other 
vendors besides IBM who offer them.

If you're running a variant of Unix like FreeBSD or Linux, you can 
also enable an RExec server, usually called "rexecd." Check the 
documentation for your operating system for more information.

Unlike STRPCCMD, the RUNRMTCMD command does require that you specify 
the host to connect to as well as a userid and password for that host. 
Although this can be a little cumbersome, it does let you run remote 
commands rom batch jobs. That would be impossible with STRPCCMD!

When running it from within an interactive session, you can get some 
of the same functionality that STRPCCMD offers by writing a little CL 
program. In that program, you can retrieve the current userid using 
the RTVJOBA command, and you can retrieve the IP address of the PC 
that's connected to the 5250 session using the QDCRDEVD API. The 
following sample code demonstrates this technique:
PGM

    DCL VAR(&RCVVAR) TYPE(*CHAR) LEN(1000)
    DCL VAR(&RCVLEN) TYPE(*CHAR) LEN(4)
    DCL VAR(&DEVICE) TYPE(*CHAR) LEN(10)
    DCL VAR(&ERRCODE) TYPE(*CHAR) LEN(8)
    DCL VAR(&IPADDR)  TYPE(*CHAR) LEN(15)
    DCL VAR(&USERID) TYPE(*CHAR) LEN(10)
    DCL VAR(&PASSWD) TYPE(*CHAR) LEN(15) VALUE('mypasswrd')
    /* FIND OUT THE IP ADDRESS OF THE PC THAT IS +
       CONNECTED TO THIS JOB.                    */

    RTVJOBA JOB(&DEVICE) USER(&USERID)

    CHGVAR VAR(%BIN(&RCVLEN)) VALUE(1000)
    CHGVAR VAR(%BIN(&ERRCODE 1 4)) VALUE(0)

    CALL PGM(QDCRDEVD) PARM(&RCVVAR    +
                            &RCVLEN    +
                            'DEVD0600' +
                            &DEVICE    +
                            &ERRCODE   )

    CHGVAR VAR(&IPADDR) VALUE(%SST(&RCVVAR 878 15))
    /* RUN A COMMAND ON THAT PC -- TIMEOUT AFTER 5 SECS      +
       ANY MESSAGES FROM THE PC GO TO A QSYSPRT SPOOLED FILE */

    OVRPRTF FILE(QSYSPRT) HOLD(*YES)

    RUNRMTCMD  CMD('start "c:\documents and settings\alexander.acctdom+
                   \my documents\weekly\credit memos\acme inc+
                   \memo84612.doc"') +
               RMTLOCNAME(&IPADDR *IP) +
               RMTUSER(&USERID) +
               RMTPWD(&PASSWD) +
               WAITTIME(5)

    DLTOVR  FILE(QSYSPRT)
    /* SHOW THE PC'S MESSAGES TO THE USER, THEN DELETE IT */

    DSPSPLF FILE(QSYSPRT) JOB(*) SPLNBR(*LAST)
    DLTSPLF FILE(QSYSPRT) JOB(*) SPLNBR(*LAST)

ENDPGM

One of the unfortunate drawbacks to RUNRMTCMD is that any messages 
from the command running on the PC get written to a spooled file. This 
means that any errors that occur on the PC are difficult to detect.

That's why, in the sample code above, I've told it to display the 
spooled file that this command creates and then delete it. That way, 
you'll see any messages from the PC, and you won't end up filling your 
spool with responses from RUNRMTCMD.

USE THE REXEC COMMAND IN QSHELL
There's also an REXEC utility available in QShell. You could use this 
instead of RUNRMTCMD. It also uses the RExec protocol and interfaces 
with the same incoming remote command service on the PC. Its advantage 
over RUNRMTCMD is that you can control where any messages from the PC 
get sent to. You could even write a QShell script that processes these 
messages and handles errors accordingly.

You can learn more about this command by reading the following page in 
the Information Center:
http://iseries.pentontech.com/t?ctl=4C27:103C2

USE THE REXEC() API
Finally, perhaps the best way to run a remote command is from an RPG 
or C program using the rexec() API. It also uses the same RExec 
protocol as the RUNRMTCMD command, but like the QShell version, it 
gives you complete control over where any messages go.

I demonstrated the rexec() API in the June 17, 2004, issue of this 
newsletter. Professional members of the iSeries Network can read that 
article at the following link:
http://iseries.pentontech.com/t?ctl=4C23:103C2

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2. BASE64 ENCODE/DECODE UTILITY
Base64 is a popular scheme used to encode binary data so that it can be 
transferred over media that requires plain text. For example, when you want 
to send a picture through e-mail, your e-mail reader will encode the picture 
using base64, transmit the base64-encoded document, and then the recipient's 
e-mail software will decode it so that the recipient can view it.

This same encoding scheme is also commonly used when storing binary data in 
HTTP cookies.

I wrote some ILE RPG routines that will encode and decode base64 data so 
that I can use it in my programs. I've turned those routines into an open 
source service program and put it on my Web site so you can download it and 
use it in your programs as well.

This utility is located in the open source section of my Web site. If you're 
interested, you can download it from the following link:
http://iseries.pentontech.com/t?ctl=4C34:103C2

I demonstrated how to create an e-mail message with a base64-encoded 
attachment in a recent article that I wrote for iSeries NEWS magazine. If 
you're interested in that article, it's called "RPG and the IFS: Text Files 
in the World" and was published in the January 2005 issue. If you have a 
ProVIP account on the iSeries Network, you can read it at the following 
link:
http://iseries.pentontech.com/t?ctl=4C30:103C2

**********************************************************************

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