Tue, May
3 New Articles

TechTip: Automatically Refresh Web Pages

Web Languages
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

Most of you have been in airports or train stations and seen the big screens that inform you that a plane or train is boarding, late, or cancelled. This information has to come from somewhere, and it has to be controlled by some kind of timer. This tip will show you a technique to do that sort of thing.

I've seen my share of dull examples showing item masters or customer sales. But everybody has a favorite song, so I'll use "top hits" for my example. You can vote and even learn something useful too!

To give you an overview, here is what you get:

  1. A "top hits" program, which also lets you cast a vote
  2. A setup program from which you can dynamically change the look of the hit list
  3. A way to prompt for colors
  4. Some JavaScript knowledge you might not be aware of

So the tone is set. Let's roll.

How to Refresh a Web Page

There are two ways (that I am aware of) you can refresh a Web page.
You can use a meta tag, which is placed in the section of the HTML document, or you can use JavaScript.

The meta tag looks like this:

This tells the browser that it should reload the page every 10 seconds by calling program form010.

(Note: In IE 7.0, you can disable the meta refresh, so if you have done that and also disabled JavaScript, this won't work.)

I have always used the meta tag method, but some clever people do things a better way. On GrizzlyWeb.com, I found a very good and useful JavaScript Refresh example that also taught me something about JavaScript that I never knew.

When you use JavaScript in an HTML document, you can write

Press F5 to re-display Pop-up

You can test it here.

To refresh the page, use one of three methods:

  • window.location.href (for JavaScript below 1.1)
  • window.location.replace (for JavaScript 1.1)
  • window.location.reload (for JavaScript 1.2)

Basically, they do the same thing; the difference is in the cache and history controlling. If you want to dig into it, check out the JavaScript Refresh example. Otherwise, just accept what your browser is doing.

Now, you need to control the refreshing, so let's look at how to get some data to refresh. I have created two sample files: WWWHITLIST holds the information about the songs in the "top hits" list, and WWWSETUP holds information about the way the list will look, the number of entries to show, refresh time, and more.

The RPG CGI program FORM010 is pretty straightforward. The flow is like this:

  1. Read input from HTML form/Query string (if any).
  2. Read setup data (I have only one record in WWWSETUP). If no data is found in setup file, a default record is created.
  3. Read HTML skeleton file from the IFS (thanks to Scott Klement for the API wrapper).
  4. Create HTML reply/read hit list data.
  5. Wait for next refresh.

The default hit list looks like this:


Figure 1: RPG CGI program FORM010 creates the default hit list with a refresh time of 10 seconds. (Click images to enlarge.)

Cast a Vote

For viewers to cast a vote, RPG CGI program FORM010 must be called with a parameter called "votemode" and must be set to Y (in uppercase). When this is done, the refresh is suspended, and the list looks like this:

Figure 2: The program is ready to accept votes.

Every time someone votes, the list will refresh. If you open another browser and load the list in refresh mode, you will of course see it change every time the refresh time is reached.

Set Up the List

I have created RPG CGI program FORM011 to change the look and feel of the list. When loaded, the program looks like this:

Figure 3: RPG CGI program FORM011 changes the look and feel of the list.

You can clearly see what you can change, and the program works the same way as any other update program except that the input is coming from an HTML form.

I found the "color prompter" at >free-color-picker.com. In my opinion, it's very clever and also easy to implement. So, for example, if you want to change the background header color, click the button. You'll see the following:

Figure 4: Prompt for a color.

When you click on a color, the color value will be transferred back to the HTML form and the pop-up will close.

Downloading and Installing

  1. Create a directory in your root directory called /root/mcpressonline by entering the following command: md '/root/mcpressonline/'
  2. Create a dir called autorefresh inside mcpressonline. Enter the following: md '/root/mcpressonline/autorefresh'
    Note: If you place it somewhere else, you must change the following files to reflect your placement: javascript file 302pop.js and variable IFSpath in FORM010 and FORM010.
  3. Download refresh.zip. Unzip and upload everything to '/root/mcpressonline/autorefresh'. It should look like this:

  4. Compile >WWWHITLIST, WWWHITLISL, and WWWSETUP or restore save file wwwhitlist.savf to your i5 (saved with TGTRLS(V5R1M0)).
  5. Save copy book for BUFIO_H to your i5.
  6. Download and save the source to FORM010 and FORM011 on your i5.

Before compiling...

  • Change the "your-data-lib" in the RPG sources to where you placed the data files.
  • Change "root-dir" in constant IFSpath to your actual root dir.
  • In FORM010, change "your-server" to your Web server name in variable reloadURL.

When you have installed everything and compiled the RPG programs (compile instructions can be found in the header description), you can test the list.

Load the list: http://your-server-name/cgi-bin/form010

Cast a vote: http://your-server-name/cgi-bin/form010?votemode=Y

Set up the list: http://your-server-name/cgi-bin/form011

When you want to add new songs to the list, enter data into WWWHITLIST using DFU or your favorite database editor.

Happy New Year

Once again, I hope this tip has proved how a little JavaScript, some good old RPG, and a few creative thoughts can help you build applications that serve data in ways you might not have thought of before.

Jan Jorgensen is a programmer at Electrolux Laundry Systems Denmark. He works with RPG, HTML, JavaScript, and Perl. You can reach him at This email address is being protected from spambots. You need JavaScript enabled to view it..

Jan Jorgensen

Jan Jorgensen is one of the owners of www.reeft.dk, which specializes in mobile and i5 solutions. He works with RPG, HTML, JavaScript, Perl, and PHP. You can reach him at This email address is being protected from spambots. You need JavaScript enabled to view it.




Support MC Press Online

$0.00 Raised:

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: