RPG IV Overview

Chapter 1. Overview

of

the

RPG

IV

Programming

Language

 

 

This chapter

presents

a

high-level

review

of

the features of the R

ming language that distinguish RPG from other

programming

languages. You

should

be familiar

and

comfortable

with

all

of these

features befor

the RPG IV language. The features discussed here encompass the fo subjects:

¹Coding specifications

¹ The program cycle

¹Indicators

¹Operation codes

For more information on RPG IV,ILEseeRPG thefor AS/400 Reference.

RPG IV Specifications

RPG code is written on a variety of specification forms, each with functions. Many of the entries which make up a specification type a dependent. Each entry must start in a specific position depending on entry and the type of specification.

There are seven types of RPG IV specifications. Each specification Specifications must be entered into your source program in the order

Main source

section:

 

 

 

 

 

 

1.Control

specifications

provide

the

compiler

with information

about

gener

and running programs, such as the program name, date format,

and us

alternate

collating

sequence

or

file translation.

 

 

2.File description

specifications

describe all

the files that

your

program

3.Definition specifications describe the data used by the program.

4.Input

specifications

describe

the

input

records and

fields

used by

program.

 

 

 

 

 

 

 

 

 

 

 

 

5. Calculation

specifications

describe the calculations done on the data

order

of

the

calculations.

Calculation specifications

also

control

ce

and

output operations.

 

 

 

 

 

 

 

 

 

 

6. Output

specifications

describe

the

output

records

and

fields

used

b

program.

 

 

 

 

 

 

 

 

 

 

 

 

Subprocedure

section:

 

 

 

 

 

 

 

 

 

 

 

 

1.Procedure

specifications

mark the beginning and end of the subprocedur

indicate

the subprocedure

name, and

whether

it

is

exported.

 

2.Definition

specifications

describe the local data used by the subpro

3.Calculation

specifications

describe

the

calculations

done

on

both

the

 

and

local

data

and the order

of the

calculations.

 

 

 

 

Copyright IBM Corp. 1994, 1999

3

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IBM AS/400 manual RPG IV Specifications, RPG IV Overview, Control Specifications, Input Specifications

AS/400 specifications

The IBM AS/400, now known as the IBM iSeries, is a midrange computer system that has been a cornerstone of enterprise computing since its introduction in 1988. Designed to provide a robust platform for business applications, the AS/400 is celebrated for its reliability, scalability, and integrated database capabilities.

One of the key features of the AS/400 is its Integrated Operating Environment, which blends hardware and software resources seamlessly. This integration allows businesses to execute diverse workloads, ranging from traditional applications to modern web-based services, all on a single platform. The operating system, OS/400 (now IBM i), offers a rich set of APIs and tools for developers, simplifying application development and management.

Another standout characteristic of the AS/400 is its built-in database, DB2 for i. This powerful relational database management system allows for efficient data handling and provides advanced features such as support for SQL, XML, and JSON, making it easier for businesses to manage their data and integrate it with other systems. The database's tight integration with the operating system enables high performance and security.

In terms of scalability, the AS/400 can accommodate small businesses as well as large enterprises, with the ability to support hundreds of users simultaneously. Its architecture allows for easy upgrades in hardware, meaning that organizations can scale their systems without replacing the entire infrastructure.

Security is another critical attribute of the AS/400. With a sophisticated security model, it offers built-in user authentication, access control, encryption, and auditing capabilities to protect data and applications from unauthorized access.

The AS/400 also supports multiple programming languages, including RPG, COBOL, Java, and PHP, giving organizations the flexibility to choose the development tools that best fit their needs. This diversity helps maintain legacy applications while also developing new ones that leverage modern technologies.

Moreover, the platform supports both traditional green-screen interfaces and modern graphical user interfaces, allowing organizations to transition smoothly into contemporary user experience paradigms.

Overall, the IBM AS/400 stands out as a resilient, flexible, and secure computing platform that enables organizations to effectively manage their business operations, streamline processes, and adapt to changing market demands. Its unique combination of integrated features and capabilities ensures that it remains relevant in today's fast-paced technology landscape.