IBM AS/400 manual RPG Programming in ILE, or CRTSRVPGM, Program Creation in ILE

RPG Programming in ILE

Alternatively,	you may create	a	program using		separate		commands		for	comp
and binding. This two-step process allows you					to	reuse	a	module	or	upd
module without	recompiling the	other		modules in	a	program.		In addition,
you can combine modules from		any	ILE	language,	you can		create		and	main
mixed-language	programs.

In the two-step process, you create a module object using the Creat (CRTRPGMOD) command. This command compiles the source statements into a module object. A module is a nonrunnable object; it must be bound into object to be run. To bind one or more modules together, use the Cre (CRTPGM) command.

Service programs are a means of packaging the procedures in one or mo modules into a separately bound object. Other ILE programs can access dures in the service program, although there is only one copy of the program on the system. The use of service programs facilitates modular maintainability. You can use off-the-shelf service programs developed by parties or, conversely, package your own service programs for third-par service program is created using the Create Service Program (CRTSRVPGM) command.

You can create a binding directory to					contain the names of modules a
programs that your program or			service	program		may	need.	A	list of	bind
ries can be specified when you create					a	program on		the	CRTBNDRPG,
CRTSRVPGM, and CRTPGM commands. They can also					be	specified		on	the
CRTRPGMOD command;	however,	the	search	for	a binding directory is done
the module is	bound at	CRTPGM	or CRTSRVPGM		time. A		binding	directory		can

reduce program size because modules or service programs listed in a directory are used only if they are needed.

Figure 5 shows the two approaches to program creation.

RPG IV source specifications

Externally described files

Copy source text

ILE HLL Modules,	RPG Module
Service Programs	(CRTRPGMOD)

ILE Program

(CRTBNDRPG)

ILE Program (CRTPGM)

One-Step Process	Two-Step Process
Figure 5. Program Creation in ILE

Once a program is created you can update the program using the Upd (UPDPGM) or Update Service Program (UPDSRVPGM) commands. This is useful, because it means you only need to have the new or changed module ob able to update the program.

For	more	information on the one-step process,	see Chapter 6,	“Creating a
with	the	CRTBNDRPG Command” on page 57. For more	information on	the two-

18 ILE RPG for AS/400 Programmer's Guide