Sidebar

TechTip: Automatically Refresh Web Pages

Web Languages
Typography
  • 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:

http://www.mcpressonline.com/articles/images/2002/autorefreshV4--01190700.jpg

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:

http://www.mcpressonline.com/articles/images/2002/autorefreshV4--01190701.jpg
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:

http://www.mcpressonline.com/articles/images/2002/autorefreshV4--01190702.jpg
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:

http://www.mcpressonline.com/articles/images/2002/autorefreshV4--01190703.jpg
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:

    http://www.mcpressonline.com/articles/images/2002/autorefreshV4--01190704.jpg
  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 jj@reeft.dk

 

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

RESOURCE CENTER

  • WHITE PAPERS

  • WEBCAST

  • TRIAL SOFTWARE

  • White Paper: Node.js for Enterprise IBM i Modernization

    SB Profound WP 5539

    If your business is thinking about modernizing your legacy IBM i (also known as AS/400 or iSeries) applications, you will want to read this white paper first!

    Download this paper and learn how Node.js can ensure that you:
    - Modernize on-time and budget - no more lengthy, costly, disruptive app rewrites!
    - Retain your IBM i systems of record
    - Find and hire new development talent
    - Integrate new Node.js applications with your existing RPG, Java, .Net, and PHP apps
    - Extend your IBM i capabilties to include Watson API, Cloud, and Internet of Things


    Read Node.js for Enterprise IBM i Modernization Now!

     

  • Profound Logic Solution Guide

    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 companyare not aligned with the current IT environment.

    Get your copy of this important guide today!

     

  • 2022 IBM i Marketplace Survey Results

    Fortra2022 marks the eighth edition of the IBM i Marketplace Survey Results. Each year, Fortra captures data on how businesses use the IBM i platform and the IT and cybersecurity initiatives it supports.

    Over the years, this survey has become a true industry benchmark, revealing to readers the trends that are shaping and driving the market and providing insight into what the future may bring for this technology.

  • Brunswick bowls a perfect 300 with LANSA!

    FortraBrunswick is the leader in bowling products, services, and industry expertise for the development and renovation of new and existing bowling centers and mixed-use recreation facilities across the entertainment industry. However, the lifeblood of Brunswick’s capital equipment business was running on a 15-year-old software application written in Visual Basic 6 (VB6) with a SQL Server back-end. The application was at the end of its life and needed to be replaced.
    With the help of Visual LANSA, they found an easy-to-use, long-term platform that enabled their team to collaborate, innovate, and integrate with existing systems and databases within a single platform.
    Read the case study to learn how they achieved success and increased the speed of development by 30% with Visual LANSA.

     

  • Progressive Web Apps: Create a Universal Experience Across All Devices

    LANSAProgressive Web Apps allow you to reach anyone, anywhere, and on any device with a single unified codebase. This means that your applications—regardless of browser, device, or platform—instantly become more reliable and consistent. They are the present and future of application development, and more and more businesses are catching on.
    Download this whitepaper and learn:

    • How PWAs support fast application development and streamline DevOps
    • How to give your business a competitive edge using PWAs
    • What makes progressive web apps so versatile, both online and offline

     

     

  • The Power of Coding in a Low-Code Solution

    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:

    • Discover the benefits of Low-code's quick application creation
    • Understand the differences in model-based and language-based Low-Code platforms
    • Explore the strengths of LANSA's Low-Code Solution to Low-Code’s biggest drawbacks

     

     

  • Why Migrate When You Can Modernize?

    LANSABusiness 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.
    In this white paper, you’ll learn how to think of these issues as opportunities rather than problems. We’ll explore motivations to migrate or modernize, their risks and considerations you should be aware of before embarking on a (migration or modernization) project.
    Lastly, we’ll discuss how modernizing IBM i applications with optimized business workflows, integration with other technologies and new mobile and web user interfaces will enable IT – and the business – to experience time-added value and much more.

     

  • UPDATED: Developer Kit: Making a Business Case for Modernization and Beyond

    Profound Logic Software, Inc.Having trouble getting management approval for modernization projects? The problem may be you're not speaking enough "business" to them.

    This Developer Kit provides you study-backed data and a ready-to-use business case template to help get your very next development project approved!

  • What to Do When Your AS/400 Talent Retires

    FortraIT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators is small.

    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:

    • Why IBM i skills depletion is a top concern
    • How leading organizations are coping
    • Where automation will make the biggest impact

     

  • Node.js on IBM i Webinar Series Pt. 2: Setting Up Your Development Tools

    Profound Logic Software, Inc.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. In Part 2, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Attend this webinar to learn:

    • Different tools to develop Node.js applications on IBM i
    • Debugging Node.js
    • The basics of Git and tools to help those new to it
    • Using NodeRun.com as a pre-built development environment

     

     

  • Expert Tips for IBM i Security: Beyond the Basics

    SB PowerTech WC GenericIn this session, IBM i security expert Robin Tatam provides a quick recap of IBM i security basics and guides you through some advanced cybersecurity techniques that can help you take data protection to the next level. Robin will cover:

    • Reducing the risk posed by special authorities
    • Establishing object-level security
    • Overseeing user actions and data access

    Don't miss this chance to take your knowledge of IBM i security beyond the basics.

     

     

  • 5 IBM i Security Quick Wins

    SB PowerTech WC GenericIn today’s threat landscape, upper management is laser-focused on cybersecurity. You need to make progress in securing your systems—and make it fast.
    There’s no shortage of actions you could take, but what tactics will actually deliver the results you need? And how can you find a security strategy that fits your budget and time constraints?
    Join top IBM i security expert Robin Tatam as he outlines the five fastest and most impactful changes you can make to strengthen IBM i security this year.
    Your system didn’t become unsecure overnight and you won’t be able to turn it around overnight either. But quick wins are possible with IBM i security, and Robin Tatam will show you how to achieve them.

  • Security Bulletin: Malware Infection Discovered on IBM i Server!

    SB PowerTech WC GenericMalicious programs can bring entire businesses to their knees—and IBM i shops are not immune. It’s critical to grasp the true impact malware can have on IBM i and the network that connects to it. Attend this webinar to gain a thorough understanding of the relationships between:

    • Viruses, native objects, and the integrated file system (IFS)
    • Power Systems and Windows-based viruses and malware
    • PC-based anti-virus scanning versus native IBM i scanning

    There are a number of ways you can minimize your exposure to viruses. IBM i security expert Sandi Moore explains the facts, including how to ensure you're fully protected and compliant with regulations such as PCI.

     

     

  • Encryption on IBM i Simplified

    SB PowerTech WC GenericDB2 Field Procedures (FieldProcs) were introduced in IBM i 7.1 and have greatly simplified encryption, often without requiring any application changes. Now you can quickly encrypt sensitive data on the IBM i including PII, PCI, PHI data in your physical files and tables.
    Watch this webinar to learn how you can quickly implement encryption on the IBM i. During the webinar, security expert Robin Tatam will show you how to:

    • Use Field Procedures to automate encryption and decryption
    • Restrict and mask field level access by user or group
    • Meet compliance requirements with effective key management and audit trails

     

  • Lessons Learned from IBM i Cyber Attacks

    SB PowerTech WC GenericDespite the many options IBM has provided to protect your systems and data, many organizations still struggle to apply appropriate security controls.
    In this webinar, you'll get insight into how the criminals accessed these systems, the fallout from these attacks, and how the incidents could have been avoided by following security best practices.

    • Learn which security gaps cyber criminals love most
    • Find out how other IBM i organizations have fallen victim
    • Get the details on policies and processes you can implement to protect your organization, even when staff works from home

    You will learn the steps you can take to avoid the mistakes made in these examples, as well as other inadequate and misconfigured settings that put businesses at risk.

     

     

  • The Power of Coding in a Low-Code Solution

    SB PowerTech WC GenericWhen 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:

    • Discover the benefits of Low-code's quick application creation
    • Understand the differences in model-based and language-based Low-Code platforms
    • Explore the strengths of LANSA's Low-Code Solution to Low-Code’s biggest drawbacks

     

     

  • Node Webinar Series Pt. 1: The World of Node.js on IBM i

    SB Profound WC GenericHave 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.
    Part 1 will teach you what Node.js is, why it's a great option for IBM i shops, and how to take advantage of the ecosystem surrounding Node.
    In addition to background information, our Director of Product Development Scott Klement will demonstrate applications that take advantage of the Node Package Manager (npm).
    Watch Now.

  • The Biggest Mistakes in IBM i Security

    SB Profound WC Generic The Biggest Mistakes in IBM i Security
    Here’s the harsh reality: cybersecurity pros have to get their jobs right every single day, while an attacker only has to succeed once to do incredible damage.
    Whether that’s thousands of exposed records, millions of dollars in fines and legal fees, or diminished share value, it’s easy to judge organizations that fall victim. IBM i enjoys an enviable reputation for security, but no system is impervious to mistakes.
    Join this webinar to learn about the biggest errors made when securing a Power Systems server.
    This knowledge is critical for ensuring integrity of your application data and preventing you from becoming the next Equifax. It’s also essential for complying with all formal regulations, including SOX, PCI, GDPR, and HIPAA
    Watch Now.

  • Comply in 5! Well, actually UNDER 5 minutes!!

    SB CYBRA PPL 5382

    TRY 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.

    Request your trial now!

  • Backup and Recovery on IBM i: Your Strategy for the Unexpected

    FortraRobot automates the routine 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:
    - Simplified backup procedures
    - Easy data encryption
    - Save media management
    - Guided restoration
    - Seamless product integration
    Make sure your data survives when catastrophe hits. Try the Robot Backup and Recovery Solution FREE for 30 days.

  • Manage IBM i Messages by Exception with Robot

    SB HelpSystems SC 5413Managing messages on your IBM i can be more than a full-time job if you have to do it manually. 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:
    - Automated message management
    - Tailored notifications and automatic escalation
    - System-wide control of your IBM i partitions
    - Two-way system notifications from your mobile device
    - Seamless product integration
    Try the Robot Message Management Solution FREE for 30 days.

  • Easiest Way to Save Money? Stop Printing IBM i Reports

    FortraRobot 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:

    - Automated report distribution
    - View online without delay
    - Browser interface to make notes
    - Custom retention capabilities
    - Seamless product integration
    Rerun another report? Never again. Try the Robot Report Management Solution FREE for 30 days.

  • Hassle-Free IBM i Operations around the Clock

    SB HelpSystems SC 5413For over 30 years, Robot has been a leader in systems management for IBM i.
    Manage your job schedule with the Robot Job Scheduling Solution. Key features include:
    - Automated batch, interactive, and cross-platform scheduling
    - Event-driven dependency processing
    - Centralized monitoring and reporting
    - Audit log and ready-to-use reports
    - Seamless product integration
    Scale your software, not your staff. Try the Robot Job Scheduling Solution FREE for 30 days.