Re: New to ILE

Hello, Rob:

I don't know what other platform(s) you might have had exposure
to, but here is my attempt to "explain ILE in layman's terms"...

                            ILE = "It's a Linkage Editor!"

All ILE compilers compile from source code to create a *MODULE,
which is an "object module" or "object text" or ".obj" in MS-DOS
or an "a.out" file in Unix/Linux.  You then use some type of "linker"
or "binder" to combine one or more "object files" to create an
executable binary file (a .exe file in MS-DOS or Windows; any file
name can be marked "executable" under Unix or Linux.)  In OS/400,
we call these objects *PGMs.

Now, in Unix, they have something called a "shared library" which
is a "subroutine library" of "shared" routines. Usually, these may be
already loaded into virtual memory for you by the Unix OS.

In Windows, MS introduced the ".dll" or Dynamic Link Library,
where each .dll file contains one or more object modules that were
"linked" to create a single loadable .dll file that can be (dynamically)
loaded (on demand) into memory, if and when needed.

In OS/400, they call these a "service program" (*SRVPGM).

The CRTPGM command is used to combine one or more
*MODULEs into a *PGM, while CRTSRVPGM is used to
combine one or more *MODULEs into a *SRVPGM.  Both
of these commands, are part of the "binder" or linker of OS/400.

UPDPGM can be used to replace one or more *MODULEs
in a *PGM (perhaps with a newer, "fixed" version). Similarly,
UPDSRVPGM can replace *MODULEs in a *SRVPGM.

All of these functions were provided by a single utilty program
of IBM's venerable mainframe OS/360, OS/VS, MVS thru OS/390,
and it is called the "Linkage Editor".

So, CRTPGM, CRTSRVPGM, UPDPGM and UPDSRVPGM
are all a part of the ILE "binder" in OS/400.

ILE Languages and Compilers
=====================
Now, for the ILE languages, you have C, C++, RPG IV and COBOL. The commands
are:

    CRTCMOD
    CRTCPPMOD
    CRTCBLMOD
    CRTRPGMOD

to create a single *MODULE from a source member.

(You can get these by using option 15=Create module in PDM).

You could then use CRTPGM to "bind" that *MODULE into
a single *PGM, or CRTSRVPGM to create a *SRVPGM.

To make this "easier" (and more "familiar" to those of us who
were familiar with the older OPM compilers, CRTRPGPGM or
CRTCBLPGM, which created a *PGM in "one step"), IBM has
also created these new ILE commands:

    CRTBNDC,    CRTBNDCBL and CRTBNDRPG

(You get these from option 14=Compile in PDM, for member
types CBLLE and RPGLE.)

I hope that helps... the best thing I can suggest is that you try out
these various commands, and see what they do. As others have
suggested, if you already know RPG/400, you can use the IBM
provided CVTRPGSRC command to help you get started.

Good luck,

Mark S. Waterbury


----- Original Message -----
From: "Rob Phillips" <niceguy420l@yahoo.com>
To: <MIDRANGE-L@midrange.com>
Sent: Thursday, January 16, 2003 7:26 PM
Subject: New to ILE


>
> Hi
>
> I am reading about ILE and I cannot get a handle on it. Can someone please
explain in simplified terms, how does it work, how is it different, what are
service programs, bindings, etc... I am lost, and I may have to start coding
this way in one week.
>
> Thanks,
>
> Rob
>
>
>
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