Acknowledgments...iii. Section 1: Introduction to /ILE... 1

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1 Contents Acknowledgments...iii Section 1: Introduction to /ILE... 1 Chapter 1: A High-Level Introduction to ILE... 3 The Organization of the Book... 4 What Is Was OPM?... 6 Problems with OPM... 6 What Makes ILE Different (and Special)... 9 Why Bother with ILE? Just Keep This in Mind What Makes a Program ILE? Now It s Your Turn What Ya Shoulda Learned Chapter 2: A Bit More ILE Procedures: The Basic Building Blocks Modules What Is a Program? And a Service Program? Creating an ILE Program: One Step or Two or Four What Ya Shoulda Learned Section 2: Introduction to /Free... 31

2 vi 21st Century RPG: /Free, ILE, and MVC Chapter 3: A First Dive into /Free RPG /Free What Is /Free? Why /Free? Who Can Use /Free? What s Not in /Free Setting Up a /Free Program Now It s Your Turn The /Free Delimiter Tags Now It s Your Turn What Ya Shoulda Learned Chapter 4: Diving Deeper into /Free Ending a /Free Program Now It s Your Turn Comments Now It s Your Turn EVAL Statement Stuff Now It s Your Turn EVAL Opcode Extenders Other EVAL Opcodes What Ya Shoulda Learned Chapter 5: /Free Control Statements IF Statement Stuff Now It s Your Turn More Complex IF Statements Comparison Operators Negative IF Statement Now It s Your Turn SELECT/WHEN... 60

3 Contents vii Now It s Your Turn DO Stuff Now It s Your Turn FOR Loop Now It s Your Turn Leaving a Loop CALLP Indent What Ya Shoulda Learned Chapter 6: /Free I/O Statements Working with Keys Another Way to Deal with Keys Now It s Your Turn Output Opcodes in /Free Workstation-Type I/O Statements Now It s Your Turn Error Checking Now It s Your Turn So, What About SQL? What Ya Shoulda Learned Section 3: Practical ILE Chapter 7: ILE Subroutines to Sub-Procedures Why Subroutines Cause Blindness Sub-Procedures Sub-Procedure Inside a Program Example Now It s Your Turn One More Thing: Debug What Ya Shoulda Learned... 94

4 viii 21st Century RPG: /Free, ILE, and MVC Chapter 8: ILE: Calling One Program from Another Calling Program: DWS The Called Program: DWS Now It s Your Turn What Ya Shoulda Learned Chapter 9: ILE Service Programs The Service Program Scenario The Service Program: DWS0260SRV Compiling the Service Program Now It s Your Turn Program That Calls a Service Program Compiling the Calling Program Now It s Your Turn Growing and Organizing Your Service Program Farm What Ya Shoulda Learned Chapter 10: A Summary of Your ILE Options Review of the Three Options And the Winner Is? A Few Thoughts Is ILE Too Complicated? What Ya Shoulda Learned Section 4: Advanced /Free Chapter 11: Function Calls and Return Values What Are These Things? Function Call/Return Values: The Details Calling Program Called Program Now It s Your Turn

5 Contents ix And One More Thing Does It Matter? What Ya Shoulda Learned Chapter 12: The Importance of BIFs BIF Essentials Numeric to Character Convert to Decimal Other Conversion BIFs Date and Time Stuff SCAN, REPLACE, XLATE Trim Now It s Your Turn Why Personal Responsibility Matters What Ya Shoulda Learned Chapter 13: H and F Position-less Specs /Free Delimiters H-specs Now It s Your Turn File Control Statements: Basic Format FCS: Details FCS: DEVICE Keyword FCS: KEYED Keyword FCS: USAGE Keyword Now It s Your Turn What Ya Shoulda Learned

6 x 21st Century RPG: /Free, ILE, and MVC Chapter 14: D and P Position-less Specs D-specs DCS: Named Constants DCS: Standalone Field DCS: Data Structures DCS: Overlay Now It s Your Turn PR and PI D-Specs Now It s Your Turn P-Specs Now It s Your Turn If/Then/Else in a Control Statement Now It s Your Turn Mixing File and Data Control Statements Now It s Your Turn What Ya Shoulda Learned Section 5: Advanced ILE Chapter 15: Prototyping Primer What Is Prototyping? Now It s Your Turn PR- and PI-specific Keywords: Top-Level Keywords PR and PI-specific Keywords: Subfield Keywords Options(*NOPASS) Skipping Parms: OPTIONS(*OMIT) Now It s Your Turn Oddball Keywords What Ya Shoulda Learned

7 Contents xi Chapter 16: More Prototyping Stuff CONST Now It s Your Turn Now It s Your Turn A Series of Facts About Parameter Size What Happens If the Field Sizes Do Not Match? Now It s Your Turn Options(*VARSIZE) and VARYING A Quick Review What Ya Shoulda Learned Chapter 17: ILE Activation Groups Basic Activation Group Facts Default Activation Group Parm (DFTACTGRP) Now It s Your Turn Activation Group Types What Happens When an Activation Group Closes? RCLACTGRP So, How Should Activation Groups Be Used? Now It s Your Turn What Ya Shoulda Learned Chapter 18: Service Program Compile Stuff Binding What Does This Have to Do with Service Programs? What Happens When You Call a Service Program? What Can Go Wrong What Ya Shoulda Learned

8 xii 21st Century RPG: /Free, ILE, and MVC Chapter 19: Binding Directories Binding Directories Binding Directory Commands To Binding Directory or Not What Ya Shoulda Learned Chapter 20: ILE Binding Language What Is Binding Language? What Is EXPORT? The Binding Language Commands RTVBNDSRC Command Triggering Binding Language Use What Binding Language Doesn t Do What Ya Shoulda Learned Chapter 21: Service Program Signatures Signatures Quick Review Signature Violations What Ya Shoulda Learned Chapter 22: ILE for CL Do You Need CLLE? Going to CLLE Calling an RPG Program from a CLLE Program Calling a CL Program from an RPG Program Now It s Your Turn Calling an RPG Sub-Procedure from a CL Now It s Your Turn What Ya Shoulda Learned Section 6: MVC

9 Contents xiii Chapter 23: Design Patterns A Few Basic Facts Design Patterns Characteristics of a Design Pattern There Is More Than One (Design Pattern) Anti-Patterns What Ya Shoulda Learned Chapter 24: MVC and Its Variants What Is MVC? Why MVC Is Important Everybody Loves MVC, but What Ya Shoulda Learned Chapter 25: MVC Example Data and Display Files Model View Controller What Ya Shoulda Learned Chapter 26: Turning Up the ILE in MVC In General Model View Controller Chapter 27: RPG and the Web RPG and Other Languages Calling RPG from Web Languages Calling Web Languages from RPG The Bottom Line

10 xiv 21st Century RPG: /Free, ILE, and MVC Chapter 28: What s Really Important The Bottom Line Write Modular Code Write Simple Code Code /Free Use ILE, Especially Sub-Procedures and Service Programs Embrace Design Patterns Keep Up to Date with What Is New Why? Index...333