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The quote above describes pretty well why I love my profession. I may sound like a real control freak but my left-brain needs an environment where it can exercise its desire for logic and order without causing too many waves, and programming is it. In my job with Safety Insurance in Boston, I create software for use by our independent insurance agents throughout Massachusetts, who now have web access to our AS/400 database for their policies and claims. I have created this software in several formats: Windows (previously OS/2) client/server applications installed on each PC, Java applets that reside on the server and are run from a web browser, web-based (Perl driven) front ends connecting via XML to the AS/400 (RPG driven) back ends through WebSphere MQ message queues, and Perl applications that use SQL to get data from the AS/400 and Sequel servers. In September of 2000, this software, named PowerDesk, was part of a system that earned Safety Insurance First Place in the Beyond Computing Magazine Partnership Awards, honoring Safety for having successfully aligned our information technology operations with our primary missions. Using XML and Perl looks like the way we will continue to do development at Safety, and one of my first enjoyable tasks using the MQ was writing an XML parser for our claim entry application. I have been programming for a couple of decades in a variety of languages, depending on the job and platform. Professionally, I have mostly used RPG, which I have worked with in various forms since the 1980s, and currently I am developing web-based server applications in Perl. As you can see from my website, for personal use I also do a lot with HTML, JavaScript, Perl, and a bit of Java.

 Perl tips & examples

I thought an easy way to show some Perl how-to info was to display some scripts I have created. Click on the Title to run the application Click on the name.pl to view the source Create link (create_link.pl) – At times I have wanted to download a file that is embedded in the HTML of a webpage and I would have to create a little webpage with a link to the file so I could use the Save Target As option on the the right mouse button context menu. This script will allow you to just type in the URL and a web link is created automatically. Since creating it I have found it useful for other things, for instance, at work I wanted my initial Perl script in one application to show a button to go back to the previous webpage if the script is called from a link (using $ENV{'HTTP_REFERER'}), but not if the script was run from a shortcut or typed into the address bar of the browser. I used the Create link script to quickly create a link to call my script for the test. My iPod songs (playsongs.pl) – I am always telling people about songs I have on my iPod, so to share some of these songs with others I uploaded them to a folder on my web server and wrote this script to access that folder. This script creates clickable links of the songs and also creates M3Us of them dynamically for streaming. (My songs had to be removed from the server so the iPod songs page has been changed.) All the songs on my iPod are stored in a folder on my PC, and to show a list of those songs I wrote two scripts: listsongs.pl ··· builds a file of the songs which I then upload to the server viewsongs.pl ··· displays that uploaded file as a list of songs (display only, not playable) Mypics (showpics.pl) (show_thumbs.pl) – I got a new little digital camera, and to show some friends the photos I was taking with it I made a script to list them dynamically as links. When I present photographs on a webpage I usually create a thumbnail of the photo to click on to see an enlargement, so I wrote a Perl script (show_thumbs.pl) to create the thumbnails dynamically, specifying a width attribute on the <img> tag for the thumbnail which creates a height with the same aspect ratio as the original image. One consideration when using this technique is that all the image files have to download completely before the page is entirely formatted with the thumbnails, but most people I know have high-speed Internet connections now so that was not a problem. The Mypics webpage runs both of these using Ajax (that is one of the best methods to embed Perl in HTML pages). Reunion Photos (skip.pl) – My high school classmate Skip sent me 68 printed photos from a class reunion, which I had offered to scan in and put on my Class Reunion page. There were so many photos that rather than create thumbnails individually like I had done for all the rest of the photos on my Reunion page I decided to clone show_thumbs.pl above to create them, and I am using Ajax to put them on the reunion page. Perl/Ajax/HTML Ajax pages... Old Saybrook photos Florida vacations photos Dog walks First Night Big Dig photos Mypics Things that make you say, "AW Crap!!!" Truck cranes at work – One technique I like to use on my website is having a simple HTML template use Ajax to call perl to format the content. This is especially useful when you have a lot of items you wish to list or display and you don't want to tediously create all the HTML to present them. You can put them in a single folder and have perl read and list them. You can even dynamically create thumbnails for photos, which I do on these pages. Videos See videos... Amusing Humor Monty Python Political satire Music – I like to show videos on my website using perl scripts in popup windows (generated in a JavaScript function like showVideo below). play_flv.pl ··· I wrote this script to play Flash videos (flv files) on my server with this Flash Video Player. Example usage: <a href="cgi-bin/play_flv.pl?filename=somefile.flv&width=400&height=360&title=Window%20Title"> To see in action click Top 10 Favorites. show_video.pl ··· I wrote this script to play other video formats, including mpg, wmv, and avi. Example usage: <a href="cgi-bin/show_video.pl?filename=somefile.mpg&width=400&height=360&title=Window%20Title"> To see in action click Granny air bag. video_embed.pl ··· Most of the videos on my website are on my server, but sometimes I like to link to videos on a remote site like YouTube, showing them in my own popups. Some browsers don't like linking directly to the videos in JavaScript, so I wrote this script to play the videos using <object> and <embed> tags. Example usage: <a href="cgi-bin/video_embed.pl?video=http://www.youtube.com/swf/l.swf|video_id=6gmP4nk0EOE&width=400&height=360&title=Window%20Title"> You have to know the path to the video ("http://www.youtube.com/swf/l.swf?video_id=..."), which is often shown in the <embed> instructions on the remote video page. If the URLs to videos already have CGI characters (which would be confused with my usage), I replace ? with | and & with ` and they will be restored in video_embed.pl. To see in action click Monty Python. This JavaScript creates a popup containing the output from the Perl script that is specified in the 'ref' variable defined below. function showVideo(ref, width, height) { var parms = 'width=' + width + ',height=' + height + ',left=200,top=200,resizable=yes' var target = 'myvideo'; // using the same target name makes all videos use the same window object popupWindow=window.open(ref, target, parms); // make the window dimensions slightly larger than the video var wplus = 10; var hplus = 55; // increase height for IE7 to accomodate location toolbar var ie7 = ((document.all) && (navigator.appVersion.indexOf("MSIE 7.") != -1)); if (ie7) { hplus = 90; } var rwdth = width + wplus; var rhght = height + hplus; popupWindow.resizeTo(rwdth,rhght); popupWindow.focus(); } This HTML link calls the popup function above with the video to play. <a href="cgi-bin/play_flv.pl?filename=somefile.flv&width=500&height=375&title=Window%20Title" onClick="showVideo(this.href,520,385);return false;"> print_source.pl – This is the script I wrote to display the source code in the above applications here on my website (which I am using here to display its own source). The way it works is that it reads in the source-file and modifies some of the elements—for example, substituting entities for < and > brackets, <br> for newline, and spaces for tab—then displays it in the browser to look just like it does in the editor.

   More...

• Using cookies
  
  Cookies provide a great way to communicate between scripts or different instances of the same script, and you can even interact with another language that supports cookies like JavaScript.

  # Read a cookie
  use CGI;
  my $q = new CGI;
  my $cookie_value = $q->cookie('cookie_name');
  			

  # Write a cookie
  use CGI;
  my $q = new CGI;
  my $cookie = $q->cookie(-name=>'cookie_name',
                          -value=>'cookie_value',
                          -expires=>"+1d");
  print header(-cookie=>$cookie);

  I wrote one multi-screen Perl application that was going to be linked from an unknown webpage, and I wanted to have an Exit button on the first screen that would return to the referring webpage. The environment variable 'HTTP_REFERER' holds the URL of the previous webpage, but if you were returning from a screen within the application it would point to that page. To make sure this button would always exit the application I saved the original referer value in a cookie to be retrieved on returns to the first screen.
  
  Here is how I did this.

  use CGI;
  my $q = new CGI;
  my $header_printed = '';
  # Check for existing cookie containing referer URL
  my $exit_link = $q->cookie('application_name');
  if (!$exit_link) {
    # If first visit to page create cookie with no expiration date to expire at session end
    $exit_link = $ENV{'HTTP_REFERER'};
    my $cookie = $q->cookie(-name=>'application_name', -value=>$exit_link);
    print header(-cookie=>$cookie);
    $header_printed = 'y';
  }
  if (!$header_printed) {
    print $q->header();
  }
  # (this is an abbreviated version of the print method, without escaped quotes)
  print "<a href="$exit_link"><img src="images/btn_exit.gif" title="Exit" width="120" height="20" border="0"></a>";

  
  
• Build a list of all files in a directory
  
  In several of my Perl examples above I use this technique to make a list of files in a directory on the server. Once you have this list there are many things you can do with it, including getting specific information about each file.

  # Load an array with the names of the files
  my @dir_contents = '';
  my $work_dir = "directory-including-relative-path";
  opendir(DIR,$work_dir) || die("Cannot open directory $work_dir!\n");
  @dir_contents = sort readdir(DIR);
  closedir(DIR);
  
  # Make a list of the name of each file from the array
  my $files = '';
  foreach $filename (@dir_contents) {
    # Replace certain characters with entities for html display
    $display_name =~ s/&/&/g;
    $display_name =~ s/\//⁄/g;
    # Get the file size
    my @stats = stat($work_dir.'/'.$file);
    my $filesize = int($stats[7]/1000).'kb';
    # Add the file name and size to the list to be printed
    $files = "$files$display_name - $filesize<br>";
  }

  
  
• Validate a URL
  
  Here is how to check the accessibility of a file on a remote server.

  # Set up the user-agent
  use LWP::UserAgent;
  my $ua = LWP::UserAgent->new;
  
  # Check the link
  my $link_url = "http://www...";
  my $response = $ua->get($link_url);
  if $response->is_success { # Link is OK
    ...
  } else { # Check specific codes on bad link
    my $rc = substr($server_response,0,3);
    if ($rc eq '400') { # Bad Request
      ...
    } elseif ($rc eq '401') { # Unauthorized
      ...
    } elseif ($rc eq '403') { # Forbidden (love the sound of that)
      ...
    } elseif ($rc eq '404') { # Not Found
      ...
    }
  }

 VARPG programming tips

Changing the default action on a project's .ivg file I liked to put my VARPG projects on a Windows menu, and by selecting the menu option have the GUI designer open the project. By default, if you select a shortcut to a project, or if you double-click on the .ivg file in Explorer it will open up a folder showing you the project's files. You can change this action with a setting in the Windows registry. Start Regedit. Open HKEY_CLASSES_ROOT\ivgfile\shell. In the right panel, double-click on the entry that says (Default).   Value data: 'Open,Edit,EditP...' Switch the order of the items to have Edit first.   Value data: 'Edit,Open,EditP...'

Calling a Windows API When I first used VARPG it was OS/2 based, and since OS/2 didn't have a taskbar like Windows it had a slightly bigger viewable area of the screen. This is not an issue in most situations, but on the 14-inch monitors with 640x480 resolution that were common back then, I found it limiting. I had created one non-scrollable window that was so big and full of graphics and essential information that when I ported the application over to Windows 95, if the user had the Taskbar property set to be Always on top (my personal preference) the bottom of the window would be hidden behind the taskbar. I decided that rather than require every user of this software to turn off this taskbar setting, or make the taskbar Auto hide, I had to create an Always on top menu option for my window so it could overlay the taskbar (saving this setting for future returns to this screen of course). The way to do this is to call a Windows API to make the window first in the Z-order. I posted this tip on the news400.com website (which I believe is long gone). This code sets the Always-on-top mode of a window. * Prototype the Win32 API function * The values for the Z-Order parameter (hwndInsertAfter) are: * 1 = Bottom most position in the stack of child windows * -2 = Bottom position of all topmost windows, above all nontopmost windows * 0 = Top position in the stack of child windows. * -1 = Top position of all topmost windows. D SetWinPos PR 1B 0 ExtProc('SetWindowPos') D DLL('USER32') D Linkage(*StdCall) D 10U 0 Value Handle D 10U 0 Value Z-Order D 10I 0 Value x D 10I 0 Value y D 10I 0 Value cx D 10I 0 Value cy D 10I 0 Value flags D hWnd S 10U 0 D flags S 5U 0 Inz(3) D bRC S 1B 0 * Get the window handle. C eval hWnd=%getatr('WIN01':'WIN01':'Handle') * To set the Window to be topmost in the Z-order: C eval bRC=SetWinPos(hWnd:-1:0:0:0:0:flags) * To set the Window to NOT be topmost: C eval bRC=SetWinPos(hWnd:-2:0:0:0:0:flags) You can also call AS/400 API's, but after developing a nice GUI interface to allow users to maintain their AS/400 passwords I found out the hard way that you can run into authority problems in that area.

Blinking text Surprisingly, VARPG doesn't have a Blink attribute for any parts. To achieve a blinking affect you alternate the Visible attribute of a part between ON and OFF, using a timer part and the TICK event. This technique works for any kind of situation where you want to toggle a visual display. I have also used it to alternate images associated with a part to produce animation. To use it, create a timer part on the window with the Visible attribute set to OFF. Experiment with the Interval and Multiplier attributes to achieve the timing you want. Be aware that since VARPG is single-threaded, depending on what else is occurring in your application you may not always get a perfectly timed blinking effect. The timer can be used for other types of animation, for instance, you can alternate images or change the location (left, top, and bottom attributes) of a part on the window canvas. Uses the TICK event to blink the text. * Turn on the timer to start generating TICK events. C eval %setatr('WIN01':'TIMER1':'Timermode')=1 * Toggle the visible setting for the text. C timer1 begact tick win01 C 'TEXTPART' getatr 'Visible' vis 1 0 C if (vis = 1) C eval %setatr('WIN01':'TEXTPART':'Visible') = 0 C else C eval %setatr('WIN01':'TEXTPART':'Visible') = 1 C endif C endact

Create macros for the LPEX editor The LPEX editor used by VARPG and CODE is easily customizable with Rexx macros. I have added a menu called Custom that has options on it I want to use often, most having hot-key mnemonics. To use the menu macro, Custom.lxl, add the line 'macro custom.lxl' (include quotes) to the Profile.lx macro (to edit click on Options » Profiles » User preferences) so that it is loaded when you start the editor. The macros must be located somewhere on the LPATH (a registry setting*), which you can view by typing 'query lpath ' in the command dialogue (Actions » Issue edit command). I keep my own macros in 'C:\MyMacros', a different location from IBM's, so that they won't get clobbered by upgrades to VARPG. To add this folder to the LPATH, I typed 'extras on c:\mymacros' in the command dialogue.    * HKEY_LOCAL_MACHINE\SOFTWARE\IBM\ADTS Client Server for AS/400\Environment\CODELPATH4   Here are 3 of my macros. Custom.lxl – menu macro WinPos.lx – open editor window in preset size and location, cascade if second window PrevPos.lx – return to previous position in source Some of the options on my Custom menu call macros that come with VARPG, for instance, the option Match begin-end calls match.lx to identify a logic block. If you haven't discovered this IBM macro, you will be amazed how useful it is. Since the mnemonic Alt-m is set up when my menu is loaded, all I have to do is put the cursor on an IF or DO statement, press Alt-m, and the matching END (or ENDIF, ENDDO) will be located with the entire block highlighted. Conversely I can put the cursor on an END statement to locate the corresponding IF or DO. Custom.lxl also sets up some other useful RPG actions. If I double-click on a line of code the entire line is highlighted, making cutting & pasting RPG code very easy. Since RPG is a columnized language, pressing Enter to create a new line can cause a problem by breaking up your code if you do this when the cursor is not at the end of a line. I have solved this by creating options to insert a blank line Before (Alt-i) or After (Alt-a) the current line. And of course, I have also modeled on some SEU actions, Alt-b will go to the bottom of the source and Alt-t will go to the top, and Alt-d will duplicate the current line, making it unnecessary to copy & paste the current line to repeat the code. I have added a toolbar icon for Find next to repeat the most recent Find operation, so you can just click to repeat (like F16 in SEU). Look for it next to the little flashlight icon for Find.

VARPG related links

VisualAge RPG
     Windows Tips and Techniques
Programming with VisualAge for RPG – the Redbook
The Rexx Language
LPEX User's Guide and Reference

For years I had a Java page on my website (back when I was a Java programmer) that is no longer linked on my main page. Maybe some day I will just put all the content here.

Open Source Initiative (OSI) – an idea whose time has come
Richard Stallman's Personal Page – leader of the free software movement
GNU's Not Unix! – the GNU Project and the Free Software Foundation
Alternative Operating Systems – from Consumer Project on Technology (CPT)
The FreeBSD Project – an advanced free OS from UC Berkeley
Copyleft.net – Geek chic!
Slashdot – News for Nerds. Stuff that matters.
The Apache Software Foundation
Perl Mongers – the Perl advocacy people
The Mozilla Organization

Linux

Red Hat -- Linux, Embedded Linux and Open Source Solutions
IBM Linux Portal
     Linux links
Linux Online
     How to Pronounce "Linux" – audio clip of Linus Torvalds pronouncing the word "Linux"
Linux Journal
Linux Documentation Project
LinuxProgramming.com
Linux Center
Red Hat Linux User's FAQ
LinuxQuestions.org

OS/2

IBM OS/2 Warp
The OS/2 WWW Homepage – MIT site includes links to many other OS/2 sites
Yahoo! Computers and Internet > Software > Operating Systems > OS/2

Miscellaneous programming and computer links
(see more at Internet & Technology links)

IBM

iSeries and AS/400: e-servers from IBM, Integrated Application Servers
IBM Corporation
    IBM Search – search IBM's sites
WebSphere MQ (formerly MQSeries)
iSeries Network – iSeries forums (formerly News400.com)
AS/400 FAQ – uses Faq-O-Matic
MIDGRANGE.COM Mailing List Archive – years of searchable threads
search400.com – the iSeries-specific search engine
    Best iSeries websites
searchDomino.com – the Domino-specific search engine

Other

MQSeries.net
RocketAware – Programmer's Webliography and Index
Developer.com
Netscape Home Page
Microsoft Homepage

Newsgroups

I used to have all the related usenet groups listed here but they don't seem to function in browsers anymore, so I am just providing links to Google Groups, where they are offered in a web format.

Windows

comp.os.ms-windows.programmer.*

Linux

comp.os.linux.*

Perl

comp.lang.perl.*

Java

comp.lang.java.*

  There are more programming newsgroups on my pages for JavaScript, Windows, and Online Tips.