17
Wed, Apr
5 New Articles

Catch of the day: RPG IV

RPG
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

The Display Module Usage (DSPMODUSG) command is an ILE tool that helps you to identify which programs were compiled referencing a particular module (modules were formerly known as programs in the Original Program Model). This easy-to-use utility is a must if you are going to use RPG IV.

If you work in an RPG II or RPG III shop and you have not already taken a serious look at RPG IV, it may be time to do so. The enhancements to RPG IV have been announced at a fast and furious pace in the last few years. The IBM development labs in Toronto have done a wonderful job of adding functionality and features to our RPG toolbox, with numerous enhancements still on the horizon. If you have not moved to RPG IV, you may be missing the boat.

The RPG source specifications have changed: There are new data types to use, and there are new op codes to explore. Lowercase source code is now allowed, and longer field names are supported. New control keywords have been added to our file specifications and the new definition specification. New free-form expression support has been added to improve string handling and mathematical formulas. IBM has even provided a conversion tool to take you from RPG III to RPG IV.

But we think IBM left out a couple of things that would be useful. In this article, we will address one of these shortcomings and offer a remedy for the problem. But before we get too carried away, let’s see if we can simply cover what is required in going to RPG IV.

Fish or Cut Bait

With all of the goodies that were added with RPG IV, you will also need to contend with the dreaded Integrated Language Environment (ILE). Frankly, we do not see what the fuss is about.

Like so many other things in life, ILE is what you make of it. If you want to approach the issue like a bull in a china closet, you can convert your code and begin to use all of the many ILE goodies that have been announced in the last several years. You can

explore service programs, activation groups, scoping, and so much more. But you can also take a little more subtle approach and kind of ease into it. You can take advantage of the many enhancements to RPG, without having to get into the more advanced ILE topics.

When we elected to move our shop from RPG III to RPG IV, ILE was the least of our worries. Oh sure, there were a few differences we knew we were going to have to contend with, but we elected to keep the changes pretty minimal.

The basic things you need to know when converting to RPG IV are as follows:
• The size of your RPG source file can no longer be 96. It now needs to be 112. The default name for the RPG IV source file is QRPGLESRC, but we prefer to put all of our source in a source file called SOURCE (pretty imaginative, huh?). Source files are created using the CRTSRCPF (Create Source Physical File) command.

• The CVTRPGSRC (Convert RPG Source) utility provided by IBM automatically converts your RPG III source to RPG IV. It is easy to use, and it provides you with a way to look at the “before” and “after” pictures. You will note that the source type before conversion was RPG, but the converted version is now RPGLE.

• The compile option (14) of PDM will compile an RPGLE source member with the CRTBNDRPG (Create Bound RPG) command, instead of the CRTRPGPGM (Create RPG Program) you are familiar with.

How about that? You now know everything you need to know to convert your code to RPG IV and begin using ILE. That was not so bad, was it?

Let’s talk about a few of the details so that you have a better understanding of the bigger ILE picture.

The source file needs to be a larger size because the specifications have changed. We are not going to get into the many advantages of RPG IV here, but numerous good books on this topic are readily available. When you run the conversion programs, you will see many of the changes take place in the before and after pictures of the source.

The most significant change you will deal with when you convert to RPG IV and ILE is that you compile individual source members into modules, instead of directly into programs. One or more modules are then bound together to make up a program. In the Original Program Model (OPM), we used to skip this step and compile the source members directly into programs. One thing you can do to minimize the trauma associated with going to ILE is to use the CRTBNDRPG command to create both the module and then the program, too. Fortunately, IBM made this the default PDM compile option for RPGLE source types.

Baiting the Hook

The original premise behind ILE was that the environment offered an opportunity to mix and match modules from different environments to create a single program. The idea was that the modules did not need to be from the same applications—or even coded in the same language. In effect, modules would become reusable code that could potentially show up in many different applications. And, for even more flexibility, ILE allows developers to decide when they want to bind modules into programs: either when the program is compiled or when it occurs at runtime (dynamically).

The idea of reusable code is one of the basic tenets of the object-oriented (OO) program model as well as one of the primary objectives of the San Francisco project (in which applications are purchased and then incorporated into other applications as components). But the idea of reusable code is not new (sorry, all of you OO devotees out there). The S/38 was one of the first “object-based” systems that allowed us to write a single program and then call that program from several different applications. The program

Fear Not…

was, for all practical purposes, reusable code. This technology was later brought to the AS/400 and then improved on.

The One That Got Away Was THIS BIG…

ILE was a wonderful way to create a multilanguage environment that can share many reusable modules. Since modules can be bound into programs, the overhead required by the dynamic program call can be eliminated. But there are some downsides too.

The biggest challenge for a software house like us was in the area of maintenance. Because we have hundreds of AS/400 systems to support and maintain, it is of vital importance that we have a clear understanding of how each module fits together when applying program maintenance. Without this critical knowledge, it is conceivable—no, make that likely—that we would not always send all of the required modules when applying program maintenance. You can imagine what a mess we would have if we bound updated modules to copies of old, improperly maintained modules.

This very challenge led us to create the tool we have included in this article. The Display Module Usage (DSPMODUSG) command allows you to see where each module is used in your system. The display output of the DSPMODUSG command may be seen in Figure 1. The output may also be printed, if so desired.

Caught a Whopper

The source code for the DSPMODUSG command is illustrated in Figure 2. The command is compiled so that it will run the MOD001RG program seen in Figure 3 on page 64. The display file for the MOD001RG program is named MOD001DF and is illustrated in Figure 4 on page 65.

The program uses the Create User Space (QUSCRTUS) API to create a user space that the Create Bound List Program (QBNLPGMI) API uses to hold a list of all programs that match the requested search criteria. It then “walks” through the user space, writing a subfile record for each entry found there. The subfile is then either printed or displayed, depending on the PrintorDsp parameter passed from the command.

Supper Time

If ILE has been a deterrent for converting your RPG III shop to an RPG IV shop, it should not continue to be. The entire effect of ILE can be minimized to such a degree that it is hardly even noticed. Your system will run faster (RPG IV programs run significantly faster than OPM programs), and you will have many more RPG tools at your disposal.

If you do elect to take advantage of the ILE , we hope that the tool provided in this article makes your job a little easier.

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

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: