AS/400 RPG Best Practices

Introduction

IBM i (AS/400) systems often use RPG (Report Program Generator) for enterprise applications. Adopting best practices ensures maintainability, performance, and security.

1. Use Free-Format RPG

Modern RPG (RPGLE) supports free-format coding, making the code more readable and maintainable.

    **Free
    DCL-S CustomerName CHAR(50);
    CustomerName = 'John Doe';
    DSPLY CustomerName;
    *INLR = *ON;
    

2. Leverage SQL for Database Operations

Use embedded SQL for efficient database interactions instead of native record-level access.

    **Free
    DCL-S CustName CHAR(50);
    EXEC SQL SELECT NAME INTO :CustName FROM CUSTOMERS WHERE ID = 1001;
    DSPLY CustName;
    *INLR = *ON;
    

3. Modularize Code with Procedures

Break complex programs into reusable procedures to improve maintainability.

    **Free
    DCL-PR GetCustomerName CHAR(50) EXTNAME('CUSTLIB');
       ID INT(10);
    END-PR;
    
    DCL-PI GetCustomerName CHAR(50);
       ID INT(10);
    END-PI;
    
    EXEC SQL SELECT NAME INTO :GetCustomerName FROM CUSTOMERS WHERE ID = :ID;
    RETURN GetCustomerName;
    

4. Use Display Files for User Interaction

Separate UI logic from business logic using DDS display files.

    A          R CUSTOMER
    A            CUSTID        5  0B  5  2
    A            CUSTNAME     20  B  7  2
    A            ENTERKEY      1  0B  9  2
    A          K  ENTERKEY
    

5. Optimize Performance

• Use appropriate indexes in DB2.
• Minimize I/O operations by retrieving only necessary data.
• Use commitment control for transactions.

6. Secure RPG Programs

Follow best security practices to protect sensitive data.

• Validate all user inputs.
• Use adopted authority instead of running programs as *ALLOBJ.
• Encrypt sensitive data before storage.

Conclusion

Following these RPG best practices ensures your applications are modern, maintainable, and secure.