How to program an Application - Revision history

Greenfive: fixed typo

2026-04-04T10:38:53Z

fixed typo

← Older revision		Revision as of 12:38, 4 April 2026
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	=== Vim ===		=== Vim ===
	Vim is most often the editor of choice for seasoned Text-UI ~~affictionados~~. Since ''vim'' is able to open files on remote-locations via URL notation, you can perfectly use it for editing on the fly from any platform vim is available for. There are even extensions for [https://github.com/kaimoku/vim-syntax-for-i syntax-highlighting] of common code.<ref>No longer working with vim 8.</ref> Automation of login can be done via [http://www.mavetju.org/unix/netrc.php ''~/.netrc'' file]:		Vim is most often the editor of choice for seasoned Text-UI aficionados. Since ''vim'' is able to open files on remote-locations via URL notation, you can perfectly use it for editing on the fly from any platform vim is available for. There are even extensions for [https://github.com/kaimoku/vim-syntax-for-i syntax-highlighting] of common code.<ref>No longer working with vim 8.</ref> Automation of login can be done via [http://www.mavetju.org/unix/netrc.php ''~/.netrc'' file]:

	* Create/edit your ''~/.vimrc'' to switch to ASCII mode on start, add:		* Create/edit your ''~/.vimrc'' to switch to ASCII mode on start, add:

PoC: /* Vim */ More precise, thanks to Yvan.

2025-12-23T19:57:21Z

Vim: More precise, thanks to Yvan.

← Older revision		Revision as of 21:57, 23 December 2025
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	ascii		ascii

	Important: The file '''must''' end with a blank line~~! Do a~~ <code>chmod 600 ~/.netrc</code> ~~for some more security~~.		Important: The file '''must'''
			* end with a blank line,
			* set <code>chmod 600 ~/.netrc</code>, otherwise the ''ftp'' command refuses to use it.

	* Edit files giving vim the remote URL:		* Edit files giving vim the remote URL:

PoC: /* A Word on Editors */ more precise

2024-10-23T14:18:41Z

A Word on Editors: more precise

← Older revision		Revision as of 16:18, 23 October 2024
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	\|-		\|-
	\|valign="top"\|'''SEU on OS/400'''		\|valign="top"\|'''SEU on OS/400'''
	\|valign="top"\|Built-in contextual support for ~~many~~ file types and kind of lines with precise column requirements.<br />Editing is done in an implicit array of blanks in permanent overwrite mode for easier placement of characters in proper position.		\|valign="top"\|Built-in contextual support for certain file types and kind of lines with precise column requirements.<br />Editing is done in an implicit array of blanks in permanent overwrite mode for easier placement of characters in proper position.
	\|valign="top"\|Can display only a few lines of code, that reduces clarity and thus forces a lot of scrolling.<br />Uniform colouring of code is increasingly uncommon and makes it even more difficult to keep an overview.		\|valign="top"\|Can display only a few lines of code, that reduces clarity and thus forces a lot of scrolling.<br />Uniform colouring of code is increasingly uncommon and makes it even more difficult to keep an overview.
	\|-		\|-

Greenfive: fixed typos

2024-02-08T18:44:17Z

fixed typos

← Older revision		Revision as of 20:44, 8 February 2024
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	{{FIXME\|Finish article.}}		{{FIXME\|Finish article.}}
	Getting started on programming the AS/400 isn't hard. According to Frank Soltis, the most effective way to get a machine sold is to actually bring an AS/400 along to the future customer, and show an C''x''O in an one hour crash course how to code a simple ''business application''.<br />		Getting started on programming the AS/400 isn't hard. According to Frank Soltis, the most effective way to get a machine sold is to actually bring an AS/400 along to the future customer, and show an C''x''O in a one hour crash course how to code a simple ''business application''.<br />
	Well, something an arbitrary business buffoon can do, you can do, too. Since the usual [[wikipedia:"Hello, World!" program\|Hello World]] is just too lame, let's start with an actually usable example: A simple address book application.		Well, something an arbitrary business buffoon can do, you can do, too. Since the usual [[wikipedia:"Hello, World!" program\|Hello World]] is just too lame, let's start with an actually usable example: A simple address book application.

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	== Preparation ==		== Preparation ==
	As you probably know from your experience with common systems, it's considered bad habit to work with administrative rights all of the time. I recommend [[Creating an User Account]] for you to properly work without accidentally doing harm to the system. ''Sign in'' as this user now. This gives you a subset of menu items in the ''main'' menu and makes your own Library your ''current library''. For now, consider this almost the same thing as using the <code>cd</code> command of a shell to make a directory your current one.		As you probably know from your experience with common systems, it's considered bad habit to work with administrative rights all of the time. I recommend [[Creating a User Account]] for you to properly work without accidentally doing harm to the system. ''Sign in'' as this user now. This gives you a subset of menu items in the ''main'' menu and makes your own Library your ''current library''. For now, consider this almost the same thing as using the <code>cd</code> command of a shell to make a directory your current one.

	As outlined in [[Filesystems and Files on the AS/400#File Types\|File Types]], we'll need to create a file to hold source code. Let's do that and make the maximum line length a bit larger for more flexibility.<ref>IBM delivers ready made, empty source files in the QGPL-Library. Every class of file has it's own source file, such as QCLSRC for CL source code. I consider this confusing: Working on multiple files is more cumbersome than working on multiple members of one file. The files in a member could be marked as a given type of content. The only drawback is that one must use distinct names on members. The QSYS.LIB-Filesystem can hold files with the same ''name'' as long as they have distinct ''types''.</ref>		As outlined in [[Filesystems and Files on the AS/400#File Types\|File Types]], we'll need to create a file to hold source code. Let's do that and make the maximum line length a bit larger for more flexibility.<ref>IBM delivers ready made, empty source files in the QGPL-Library. Every class of file has it's own source file, such as QCLSRC for CL source code. I consider this confusing: Working on multiple files is more cumbersome than working on multiple members of one file. The files in a member could be marked as a given type of content. The only drawback is that one must use distinct names on members. The QSYS.LIB-Filesystem can hold files with the same ''name'' as long as they have distinct ''types''.</ref>

PoC: /* Vim */ +nowiki

2021-10-21T10:27:24Z

Vim: +nowiki

← Older revision		Revision as of 12:27, 21 October 2021
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	* Edit files giving vim the remote URL:		* Edit files giving vim the remote URL:
	vim ftp://my-machine-name/mylib/mysrcpf.mymember		vim <nowiki>ftp://my-machine-name/mylib/mysrcpf.mymember</nowiki>

	With this toolset, you can develop with a tall ''vim'' window on your desktop machine, klick on a 5250-session to compile and maybe have a second 5250 session open for running the program.		With this toolset, you can develop with a tall ''vim'' window on your desktop machine, klick on a 5250-session to compile and maybe have a second 5250 session open for running the program.

PoC: /* Vim */ Details how to do it

2021-10-21T10:27:05Z

Vim: Details how to do it

@@ Line 49: / Line 49: @@
 === Vim ===
-Vim is most often the editor of choice for seasoned Text-UI affictionados. Since ''vim'' is able to open files on remote-locations via URL notation, you can perfectly use it for editing on the fly from any platform vim is available for. There are even extensions for [https://github.com/kaimoku/vim-syntax-for-i syntax-highlighting] of common code. Automation of login can be done via [http://www.mavetju.org/unix/netrc.php ''~/.netrc'' file].
+Vim is most often the editor of choice for seasoned Text-UI affictionados. Since ''vim'' is able to open files on remote-locations via URL notation, you can perfectly use it for editing on the fly from any platform vim is available for. There are even extensions for [https://github.com/kaimoku/vim-syntax-for-i syntax-highlighting] of common code.<ref>No longer working with vim 8.</ref> Automation of login can be done via [http://www.mavetju.org/unix/netrc.php ''~/.netrc'' file]:
 With this toolset, you can develop with a tall ''vim'' window on your desktop machine, klick on a 5250-session to compile and maybe have a second 5250 session open for running the program.

PoC: /* Weblinks */ +link

2020-07-11T15:38:12Z

Weblinks: +link

← Older revision		Revision as of 17:38, 11 July 2020
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	== Weblinks ==		== Weblinks ==
	* [https://www.pocnet.net/computer/fallout/ Helper Programs] for the Fallout Role Playing Game Series		* [https://www.pocnet.net/computer/fallout/ Helper Programs] for the Fallout Role Playing Game Series
			* [https://github.com/PoC-dev/as400-sfltemplates Templates] for easy development of one-database-table maintenance programs

	== Footnotes ==		== Footnotes ==

PoC: De-whichified

2020-03-12T22:03:41Z

De-whichified

PoC: /* Vim */ Added pics

2020-03-09T22:08:50Z

Vim: Added pics

← Older revision		Revision as of 00:08, 10 March 2020
Line 52:		Line 52:

	With this toolset, you can develop with a tall ''vim'' window on your desktop machine, klick on a 5250-session to compile and maybe have a second 5250 session open for running the program.		With this toolset, you can develop with a tall ''vim'' window on your desktop machine, klick on a 5250-session to compile and maybe have a second 5250 session open for running the program.
			<gallery class="center">
			File:Vim-screen-dspf-dds.png\|Vim showing 91 lines of DDS
			File:Vim-screen-rpgle.png\|Vim showing 91 lines of RPG IV positional code
			</gallery>

	== Preparation ==		== Preparation ==

PoC: According to Mark W, too much credit to Frank

2020-03-08T13:53:52Z

According to Mark W, too much credit to Frank

← Older revision		Revision as of 15:53, 8 March 2020
Line 1:		Line 1:
	{{FIXME\|Finish article.}}		{{FIXME\|Finish article.}}
	Getting started on programming the AS/400 isn't hard. According to Frank Soltis, ~~<ref>The Inventor of most of the distinct features of the AS/400.</ref>~~ the most effective way to get a machine sold is to actually bring an AS/400 along to the future customer, and show an C''x''O in an one hour crash course how to code a simple ''business application''.<br />		Getting started on programming the AS/400 isn't hard. According to Frank Soltis, the most effective way to get a machine sold is to actually bring an AS/400 along to the future customer, and show an C''x''O in an one hour crash course how to code a simple ''business application''.<br />
	Well, something an arbitrary business buffoon can do, you can do, too. Since the usual [[wikipedia:"Hello, World!" program\|Hello World]] is just too lame, let's start with an actually usable example: A simple address book application.		Well, something an arbitrary business buffoon can do, you can do, too. Since the usual [[wikipedia:"Hello, World!" program\|Hello World]] is just too lame, let's start with an actually usable example: A simple address book application.

← Older revision		Revision as of 00:03, 13 March 2020
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	RPG and COBOL are available in two flavors: [[wikipedia:Integrated Language Environment\|ILE]] and [https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_73/ilec/opmdesc.htm OPM]. See linked explanations for details.		RPG and COBOL are available in two flavors: [[wikipedia:Integrated Language Environment\|ILE]] and [https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_73/ilec/opmdesc.htm OPM]. See linked explanations for details.

	It makes no sense to utilize OPM compilers for new projects. It's best you save space and deinstall these as well as the ''*PRV'' variants, ~~which~~ generate code for the immediately previous OS release. We'll solely focus on ILE since it has (amongst others) the advantage of linking (binding) compiled object code from different languages together to form a program.		It makes no sense to utilize OPM compilers for new projects. It's best you save space and deinstall these as well as the ''*PRV'' variants, that generate code for the immediately previous OS release. We'll solely focus on ILE since it has (amongst others) the advantage of linking (binding) compiled object code from different languages together to form a program.

	The IBM website features [https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_74/rzahg/rzahglanguages.htm extensive documentation] for each language.		The IBM website features [https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_74/rzahg/rzahglanguages.htm extensive documentation] for each language.
Line 39:		Line 39:
	\|valign="top"\|'''SEU on OS/400'''		\|valign="top"\|'''SEU on OS/400'''
	\|valign="top"\|Built-in contextual support for many file types and kind of lines with precise column requirements.<br />Editing is done in an implicit array of blanks in permanent overwrite mode for easier placement of characters in proper position.		\|valign="top"\|Built-in contextual support for many file types and kind of lines with precise column requirements.<br />Editing is done in an implicit array of blanks in permanent overwrite mode for easier placement of characters in proper position.
	\|valign="top"\|Can display only a few lines of code, ~~which~~ reduces clarity and thus forces a lot of scrolling.<br />Uniform colouring of code is increasingly uncommon and makes it even more difficult to keep an overview.		\|valign="top"\|Can display only a few lines of code, that reduces clarity and thus forces a lot of scrolling.<br />Uniform colouring of code is increasingly uncommon and makes it even more difficult to keep an overview.
	\|-		\|-
	\|valign="top"\|'''Other on other platforms'''		\|valign="top"\|'''Other on other platforms'''
	\|valign="top"\|Familiar operation and UI.<br />Easy content duplication with clearly visible text range selection, and copy-paste.<br />Possibility to create custom rules for syntax highlighting.		\|valign="top"\|Familiar operation and UI.<br />Easy content duplication with clearly visible text range selection, and copy-paste.<br />Possibility to create custom rules for syntax highlighting.
	\|valign="top"\|Cumbersome handling: After every change ~~which~~ should result in a compile run, changed files have to be transferred back in some way.		\|valign="top"\|Cumbersome handling: After every change that should result in a compile run, changed files have to be transferred back in some way.
	\|}		\|}

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	== Coding the Database Table ==		== Coding the Database Table ==
	We're going to code the description of a database file, ~~which~~ is the traditional way to create database files in OS/400.<ref>Database files can also be created with the interactive SQL facility, though. But one can't derive a textual description from a SQL created database file.</ref> The ''language'' for the statements is called ''DDS''<ref>Data Description Statements.</ref> ~~which~~ is not a line oriented description like HTML. The position of statements within one line are also important.<ref>This stems from old times when punch cards were used for programming stuff. Since compatibility is mandatory, IBM extended DDS from time to time with new keywords, but left the previous stuff alone.</ref>		We're going to code the description of a database file, that is the traditional way to create database files in OS/400.<ref>Database files can also be created with the interactive SQL facility, though. But one can't derive a textual description from a SQL created database file.</ref> The ''language'' for the statements is called ''DDS''<ref>Data Description Statements.</ref> that is not a line oriented description like HTML. The position of statements within one line are also important.<ref>This stems from old times when punch cards were used for programming stuff. Since compatibility is mandatory, IBM extended DDS from time to time with new keywords, but left the previous stuff alone.</ref>

	For an address book, let's assume the following fields are of primary interest:		For an address book, let's assume the following fields are of primary interest:
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	Physical Files must have exactly one record format.		Physical Files must have exactly one record format.

	The next few lines define the fields of the database file. I don't want getting unnecessary initial complexity, so I defined all fields as ch'''a'''racter with static 48 places.<ref>The AS/400 database knows about ''varchar'' field, but the handling in the code later would be really clumsy. So I refrain from that for now. Not used places are automatically filled with blanks.</ref> The ''Birthday''-field is the only exception, ~~which~~ is defined as a date field.		The next few lines define the fields of the database file. I don't want getting unnecessary initial complexity, so I defined all fields as ch'''a'''racter with static 48 places.<ref>The AS/400 database knows about ''varchar'' field, but the handling in the code later would be really clumsy. So I refrain from that for now. Not used places are automatically filled with blanks.</ref> The ''Birthday''-field is the only exception, that is defined as a date field.

	Some fields may be left empty. To save space, these may be NULL, ~~which~~ is not the same as ''empty''. Therefore they are defined with an additional parameter ''alwnull''.<br />		Some fields may be left empty. To save space, these may be NULL, that is not the same as ''empty''. Therefore they are defined with an additional parameter ''alwnull''.<br />
	NULL fields permit fields of records to utilize no space at all, but need special attention in the code. This isn't as clumsy as coping with ''varlen'' strings, though.		NULL fields permit fields of records to utilize no space at all, but need special attention in the code. This isn't as clumsy as coping with ''varlen'' strings, though.

	The last three lines denote ''key fields''. When reading records, they'll be retrieved in key order (ascending by default). According to the first line, entries must be ''unique'' over all key fields. So you may not have more than one entry named Fred Flintstone born on 1989-08-20. This is a somewhat crude way to prevent duplicates.<ref>If Fred has more than one place to live, the right way to handle that would be to create a second table ~~which~~ lists every possible street address for a given Tuple Name—First Name—Birthday. Of course we might introduce entry IDs to keep the address table small. As said, I want to keep complexity low.</ref>		The last three lines denote ''key fields''. When reading records, they'll be retrieved in key order (ascending by default). According to the first line, entries must be ''unique'' over all key fields. So you may not have more than one entry named Fred Flintstone born on 1989-08-20. This is a somewhat crude way to prevent duplicates.<ref>If Fred has more than one place to live, the right way to handle that would be to create a second table that lists every possible street address for a given Tuple Name—First Name—Birthday. Of course we might introduce entry IDs to keep the address table small. As said, I want to keep complexity low.</ref>

	After saving the member, one may type ''14'' into the field of the ''wrkmbrpdm'' members list to instruct it to compile the file with default values to the default location ~~which~~ is your current library.		After saving the member, one may type ''14'' into the field of the ''wrkmbrpdm'' members list to instruct it to compile the file with default values to the default location that is your current library.

	=== A Word about the Compilation of Objects ===		=== A Word about the Compilation of Objects ===
	Compilation per default takes place as background (batch) job ~~which~~ is more friendly to other tasks running in interactive mode but it's a bit clumsy to handle. One needs to look into the session's [[Messages and Message Queues\|message queue]] to see if the compilation succeeded or failed, to be followed by a look into the [[Spooled Files and Output Queues\|spooled file]], searching the verbose compiler output for possible culprits.<br />		Compilation per default takes place as background (batch) job that is more friendly to other tasks running in interactive mode but it's a bit clumsy to handle. One needs to look into the session's [[Messages and Message Queues\|message queue]] to see if the compilation succeeded or failed, to be followed by a look into the [[Spooled Files and Output Queues\|spooled file]], searching the verbose compiler output for possible culprits.<br />
	One may press <code>F18</code> in the ''wrkmbrpdm'' screen to access another screen with user based defaults. The third option must be set to ''N''.		One may press <code>F18</code> in the ''wrkmbrpdm'' screen to access another screen with user based defaults. The third option must be set to ''N''.