IBM REXX (Restructured Extended Executor) is a programming language that was developed in the 1970s for ease of use and portability. It is widely used for scripting, automation, and batch processing tasks, and it has been integrated into many IBM products such as OS/2, VM, and z/OS. REXX has a simple and clear syntax, making it accessible to both beginners and experienced programmers.

Module 1: Introduction to REXX

• Overview of REXX
  • History and evolution of REXX.
  • Features and capabilities.
  • Where REXX is used (IBM mainframe environments, automation, system administration).
• Setting Up the Environment
  • Installing and configuring a REXX interpreter.
  • Running simple REXX programs on mainframes and in local environments.

Module 2: Basic Syntax and Structure

• REXX Syntax Basics
  • The structure of a REXX program.
  • The role of statements, commands, and operators.
  • The EXIT and RETURN statements.
• Writing Your First REXX Program
  • Simple “Hello World” program.
  • Printing output using the SAY command.
  • Writing and executing basic REXX scripts.

Module 3: Variables, Constants, and Data Types

• Variables
  • Defining and assigning values to variables.
  • Understanding variable types (string, numeric, etc.).
• Data Types
  • String handling: concatenation, length, trimming, substrings.
  • Working with numbers and lists.
  • Lists and arrays in REXX.
• Constants and Symbols
  • Defining constants in REXX.
  • Symbol tables and variable scope (local vs. global).

Module 4: Control Flow Statements

• Conditional Statements
  • IF, THEN, ELSE, ELSEIF, SELECT.
  • Using WHEN and OTHERWISE for case-based decisions.
• Loops and Iteration
  • DO loops: ITERATE, LEAVE, and END.
  • DO WHILE and DO UNTIL loops.
  • Iterating through lists and arrays.
• Exit from Loops
  • Using EXIT to terminate loops and functions early.

Module 5: Functions and Procedures

• Built-in Functions
  • String functions (e.g., SUBSTR, LENGTH, STRIP, INDEX).
  • Numeric functions (e.g., ABS, ROUND, INT).
  • List handling functions (e.g., PUSH, POP, LENGTH).
• User-Defined Functions
  • Defining and calling functions.
  • Passing parameters to functions.
  • Returning values from functions.
  • Creating recursive functions.

Module 6: File I/O and System Integration

• File Handling
  • Opening, reading, and writing to files.
  • Redirecting output and input from files.
  • Using OPEN, CLOSE, READ, and WRITE commands.
• Interfacing with the System
  • Invoking external programs and shell commands from REXX.
  • System calls and process control.
  • Handling standard input and output.

Module 7: Error Handling and Debugging

• Error Handling Techniques
  • Using SIGNAL to handle exceptions and errors.
  • Raising custom errors with EXIT.
  • Handling invalid operations gracefully.
• Debugging Tools
  • Enabling and using REXX trace mode.
  • Using TRACE and SAY for debugging.
  • Viewing variable values at runtime.

Module 8: Advanced Topics

• Working with Complex Data Structures
  • Using multi-dimensional arrays (lists of lists).
  • Building and manipulating complex data structures.
• Performance Optimization
  • Improving performance in large REXX programs.
  • Efficient data manipulation techniques.
• Interfacing with IBM Mainframe Applications
  • Using REXX with IBM CICS, DB2, and z/OS.
  • Integrating REXX with batch jobs and job scheduling tools.

Module 9: REXX in Automation and Scripting

• Automating System Tasks
  • Writing REXX scripts to automate routine tasks.
  • Scheduling and executing batch jobs using REXX.
  • Integration with job scheduling systems on z/OS.