IBM Version 4 manual Using APIs-Benefits, Because, Saved Overhead Processing When You Call

CL

ProgramCommands

Application

High-Level

Languages

HLL

ProgramCalls

Application

ILE C for AS/400

orMI MI Application

Licensed Programs

OS/400

User

Exit

Application

Exits

Machine Interface

Licensed Internal Code

CL commands

Callable programs

Exit programs

Machine Interface Instructions

(accessible through ILE C for AS/400 or MI programming languages)

RV3W217-1

Figure 1-1. How APIs Fit into the AS/400 Business Computing System Structure

Using APIs—Benefits

Although some CL commands and some			OS/400 APIs	perform the same basic
functions, APIs often	can	provide	additional	performance improvements and
to functions. Benefits	for	using	APIs include	the following:

Ÿ APIs are slightly faster than the following:

–Using the equivalent command or calling a CL program to call the command.

– Coding a

call

to

a command

by

using

the

Process

Commands

(QCAPCMD)

API

because

the

API

is

saved

the overhead

of

processing

a co

When

you

call

an

API,

you

do

not

have

to go

through

the

command

lyzer.

–Using the system function in the ILE C language that processes c mands.

1-2System API Programming V4R1