ISeries and AS/400 RPG IV at Work Book

	Preface	xv
Chapter 1	Performance Starts with Program Design	1
	A Thousand-Mile Journey Begins with a Single Step	1
	I/O and Its Effect on AS/400 Performance	2
	The Path You Choose Might Be the Most Important Part of Your Journey	7
	Logical Files Are a Valuable Tool, but Don't Overuse Them	9
	Blocking Data to Make the Most of I/O Processing	9
	Using SETOBJACC to Reduce I/O and Maximize Memory Usage	11
	Too Much of a Good Thing Can Kill You	16
	Reusing Deleted Records	16
	The RGZPFM Command	17
	The RGZPFFLTR Command	19
	Performance and the Dynamic Program Call	19
	ILE Performance Issues	22
	Reducing the Size of Your Programs	25
	Reducing Screen I/O in Your Interactive Programs	26
	Service Programs Can Affect Performance	27
	Do not Overlook the Obvious	28
	The Blame Game	29
	Performance, Performance, Performance	29
Chapter 2	Subfiles Belong in Every Programmer's Toolbox	31
	The Basics	32
	The Subfile Record Format (SFL) DDS	33
	The Subfile Control Record Format (SFLCTL) DDS	34
	Loading the Subfile	38
	The Relationship Between Subfile Size (SFLSIZ) and Subfile Page (SFLPAG)	39
	The Page Keys and Their Relationship to the Subfile	40
	Controlling Which Page of the Subfile You see First	41
	The Subfile End (SFLEND) Keyword	43
	Coding the "Customer Subfile" Display File	45
	Coding the "Customer Subfile" RPG Program	48
	Coding the State Lookup Window Subfile Display File	53
	Coding the State Lookup Window Subfile RPG Program	54
	Error Handling with a Message Subfile	57
	Using Search Fields in the Subfile Control Record Format	60
	Hooray for Subfiles!	68
Chapter 3	We Do Windows (and Menu Bars, Too)!	69
	How to Enhance Your Green Screens	70
	Hardware and its Effect on Enhanced DDS Applications	71
	My Screen Still Doesn't look Right	72
	The Menu Bar	72
	DDS Keywords for Coding the Menu Bar	74
	Coding RPG for Menu Bars and Pull-Down Menus	79
	Single-Choice, Pull-Down Menus	81
	Radio Push Buttons	82
	Multiple-Choice, Pull-Down Menus	83
	Pull-Down Menu Shortcut Keys	85
	Pull-Down Menu Accelerator Keys	85
	Controlling the Attributes of Available/Unavailable Choices	86
	Setting Pull-Down Menu Defaults	87
	To Menu Bar or Not to Menu Bar	87
	We do Windows	87
	Who Needs Windows?	88
	The Window Keyword	89
	System Rules for Automatic Window Placement	91
	Window Border Keyword	91
	Window Title Keyword	92
	Remove Window Keyword	93
	User Restore Display Keyword	93
	Windows and Response Time	94
	The System Request Window Program	94
	Scroll Bars and Subfiles	99
	GUI This, and GUI That	99
Chapter 4	Information Data Structures and Error Handling	101
	File Information Data Structure	101
	Field Definitions	104
	Program Status Data Structure	116
	Implementing the *PSSR Subroutine	121
	Information is Power	127
Chapter 5	Tips and Techniques for the RPG/400 Programmer	129
	Removing Leading Blanks (Left Justify)	131
	Translate (XLATE) Performs Single-Character Substitution within Character Strings	131
	Using Biton/Bitoff Operation Codes	132
	Using RTNDTA in File Maintenance	133
	Processing Multiple Views of the Same Database File	135
	Pass the Parameter, if You Please	136
	Using a RTNCOD Parameter Between Programs	137
	Using the Indicator Array	138
	Using Indicators as Field Names	139
	Retrieving the Program Name	139
	Using Multiple Format Files	140
	Localized Indicators	141
	Display Attributes without Indicators	142
	Using the Clear Op Code	143
	Soft Coding Function Keys	144
	Header Specification Compile Options	146
	The Header Specification and Its Effect on Debug	146
	Who Pulled the Trigger?	147
	A Diverse Arsenal Is Your Best Defense	150
Chapter 6	The Power of Command Processing APIs	151
	The What, the Why, and the How of Command Execute (QCMDEXC)	152
	Running OPNQRYF to Sort a Database File from within an RPG Program	153
	Overriding Printer Parameters from within an RPG Program	155
	Submitting a Job to the Job Queue from within an RPG Program	158
	QCMDEXC: An API for All Seasons	162
	The Command Processing (QCAPCMD) API	162
	C Function: System	165
	Prototyping the Call to QCMDEXC	167
	Command Performance	167
Chapter 7	Array and String Handling	169
	What Is an Array?	169
	What Would You Use an Array for?	170
	Array Basics	170
	The Runtime Array	171
	Using Runtime Arrays to Store and Accumulate Totals	173
	Sequencing Runtime Arrays for Output Operations	175
	Using Runtime Arrays to Format Data for Output	179
	The %ELEM Built-in Function Prevents Array Index Errors	182
	Runtime Array Handling RPG Op Codes	183
	The Compile-Time Array	184
	Alternative Definition of Arrays	187
	Arrays Can Be Very Dynamic	189
	String Handling Isn't Just for People with Yo-Yos Anymore	189
	Everybody Wants to Be a Cat	193
	Check, Please	197
	CHECKR Validates Character Strings from Right to Left	198
	Using the %TRIM Built-in Function to Remove Leading and Trailing Blanks	198
	Using the %TRIML Built-in Function to Remove Leading Blanks	199
	Removing Trailing Blanks	200
	Journey to the Center of the Earth	201
	Seek and Ye Shall Find--with Scan	202
	Substring (SUBST) Ties the Whole String-Handling Thing Together	203
	Translate (XLATE) Performs Single-Character Substitution Within Character Strings	205
	Final Words About Array and String Handling	206
Chapter 8	Data Structures, Data Areas, and the Local Data Area	207
	The Data Structure	208
	Data Areas	220
	The Local Data Area	226
	Using Externally Described Data Structures to Define Program-Described Data Files	229
	Using Data Structures to Reduce Program Parameters	231
	Multiple-Occurrence Data Structures and the Two-Dimensional Array	232
	Your RPG Treasure Chest	237
Chapter 9	System APIs	239
	What Is an API?	240
	Retrieve APIs	242
	Putting the Power of Retrieve APIs to Use	242
	The Optional API Error Code Parameter	244
	Using APIs to Retrieve Object Descriptions	245
	Checking for Objects Using the Retrieve Object Description (QUSROBJD) API	248
	Message APIs	249
	User Spaces	256
	List APIs	259
	Display Access Path Command	262
	Spool File APIs	274
	Program APIs for ILE	286
	Display Module Programs (DSPMODPGM)	287
	Working with Service Programs	289
	Encryption APIs	291
	Don't Worry, Be API!	296
Chapter 10	Tracking Down Problems	297
	Finding Debug in De Program	297
	Debug 101	298
	Debug Header Specifications	299
	In De Beginning	300
	Adding De Breakpoint	301
	De Conditional Breakpoint	302
	Debugging Service Programs	303
	Running De Program	306
	Displaying De Variable	306
	Using Debug to Decipher I/O Problems	310
	De Small Print	310
	Debugging Batch Jobs	311
	Journaling as a Debug Tool	314
	Job Logs and Problem Determination	320
	Solutions Are Best Found by Those Who Know How to Look for Them	326
Chapter 11	Tools for the Toolbox	327
	The Display Path (DSPPTH) Command	328
	The Display Field (DSPFLD) Command	339
	The Reorganize Physical File Filter (RGZPFFLTR) Command	348
	The Find Displaced Logical File (FNDDSPLF) Command	355
	The Work with Object Reference (WRKOBJREF) Command	362
	The Service Program Usage (SERPGMUSAG) Command	377
	The Module Usage (MODUSAG) Command	384
	The Work with Fields (WRKFLD) Command	391
	The Display File Description (DSPFILDSC) Command	405
	Scan Joblog (SCNJOBLOG) Command	415
	Find Source (FNDSRC) Command	425
	Final Words about Tools in the Toolbox	435
Chapter 12	Working with Date and Time Data Types	437
	The Date and Time Data Types	437
	It's Elementary	438
	What You See is Not Always What You Get!	439
	Apples and Apples	440
	Deciding on a Format	440
	From Soup to Nuts	441
	A Rose by Any Other Name	443
	Readin, Ritin, and Rithmatic	445
	What Is the Downside?	445
	Date Arithmetic	449
	Date Formatting	451
	Using Data Types to Format Output	455
	Date Conversion	463
	Data Type Performance	469
	The Dating Game	472
Chapter 13	ILE Concepts	473
	Modules	474
	Exports	474
	Imports	475
	Programs	475
	Binding	476
	Service Programs	477
	Binder Language	478
	The Commands	478
	Servicing the Service Program	480
	Cascading References	481
	Tips for Good Service	481
	Lip Service	482
	Activition Groups	482
	Scoping	484
	ILE Be Good	485
Chapter 14	ILE Procedures	487
	Subprocedures vs. Main Procedures	488
	Parameter Keywords	491
	Compiling	502
	Binding Directory	503
	Activation Group Considerations	503
	Putting Header Specifications into Your Programs	504
	The Subprocedure Addiction	504
Appendix	About the CD-ROM	505
	Transferring the Source	509
	Compiling the Power Tools	510
	Compiling the Rest of the Source	510
	Index	513