21
Tue, May
3 New Articles

ILE Binding Language, Part 2

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

What Binding Language Doesn’t Do

Editor's Note: This article is excerpted from chapter 20 of 21st Century RPG: /Free, ILE, and MVC, by David Shirey.

Please see the previous articles here: Binding Directories and ILE Binding Language, Part 1

Not to start on a negative note, but I thought we would begin by looking at a couple of things that binding language doesn’t do.

Binding Language Is Not Needed for Export

I know I have seen articles that say that for certain types of exports you need to use binding language. Specifically, for cases where you are calling a service program sub-procedure from a program outside of the service program module.

But that’s not what my testing shows. Just for the record here, when I am using service programs I try to be good and follow all the rules. So I don’t spend my days doing weird things. Seems like a waste of time. But for this book I did try weird things to see how far the rules can be bent. I see no evidence that you have to use binding language for certain types of exports.

Binding Language Doesn’t Prevent the Wrong Sub-Procedure from Being Called

OK, this relates to what we said in chapter 19 about the fact that it is possible, in a service program, to call the wrong sub-procedure. And, again, I have seen articles that imply that using binding language prevents this from happening, and I think that is a bit of an overstatement. Now, this will take a few minutes, but stay with me.

Suppose you have a service program that has more than one sub-procedure. Let’s say it has two. And let’s say that they are Procedure1 and Procedure2, listed in the service program in that order. Feel free to follow along at home with this one using a service program you have written. By this time, it shouldn’t be any big deal at all to write one.

Start by creating a binding language source for that service program, with the sub-procedures listed with Procedure1 first and Procedure2 second. Save that in QSVRSRC.

Next, just to make sure we are kosher, let’s compile the service program in the procedure 1-2 configuration using the CRTRPGMOD and CRTSRVPGM combo with the EXPORT parm set to *SRCFILE (that is, we will be using binding language). Be sure to do the CRTRPGMOD so that you can get into debug.

Then compile your calling program, set to call Procedure2, with CRTRPGMOD (again set up for debug), and then CRTPGM to tie everything together.

Set a breakpoint in the calling program where you call the sub-procedure and start the program. Use F22 to jump into your service program, and you should jump in at the start of Procedure2. So far, so good.

Now go into the source for the service program and move Procedure1 so that it is after Procedure2. Go ahead, I will wait. And then, recompile it (first as a module: CRTRPGMODW with debug, and then CRTSRVPGM, again using *SRCFILE). But don’t recompile the calling program. We want a way to be able to change the service program but not have to recompile the calling program. You have to recompile the service program, of course, because when the program runs, the IBM i doesn’t run the source but the object. Am I being too elementary?

Now, call this service program from a calling program that is calling Procedure2. Put the calling program in debug and use F22 to jump from calling to called (the service program). What sub-procedure is accessed, Procedure1 or Procedure2?

And the answer is Procedure1. Even though Procedure2 is now the first sub-procedure in the service program, the compile with *SRCFILE has used the binding language list in QSRVSRC, and we have picked up the second sub-procedure (Procedure1).

Now go in, and just do the CRTSRVPGM using *ALL as the EXPORT parm. Then redo the CRTPGM so that you pick up the new service program, and repeat your test. Which sub-procedure is picked up? That’s right. This time you pick up Procedure2. *ALL has generated a new list of all modules with the EXPORT keyword on the P-spec.

Now at this point, binding language aficionados will say, “but you need to change the binder source when you switch the order of the sub-procedures,” and they are right. If we had changed the binding language source file when we swapped the sub-procedures and compiled the service program using *SRCFILE, then we would have ended up calling the right sub-procedure.

But you can also argue that if you hadn’t used *SRCFILE, that is, if you hadn’t used binding language, you wouldn’t have run into this.

And because of that, right now you are probably thinking, “I ain’t using no binding language,” but it may not be that simple. You will want to hold off making a decision until we go through signatures in the next chapter.

Does This Really Happen?

Of course, any normal person at this point will say, “but who is going to move their sub-procedures around in a service program? Is this really going to happen in the real world?”

Let’s skip the fact that I might rearrange things in a service program so that like modules are near each other (a total waste of time, but one that sounds like the kind of thing I would do).

Rearrangement doesn’t happen, but often it occurs when you add or delete sub-procedures from a service program. That will push a given sub-procedure up or down in the list position and so is where you might run into this.

For this reason, it is recommended that you add new items to the bottom of your service program. But that in itself doesn’t fix things. You still have to recompile and rebind, and so you still have the situation described above.

Besides, if you add or delete sub-procedures, then you run into signature violations, and that will catch you before you can run the wrong sub-procedure. But that is a topic for the next chapter.

That doesn’t sound real positive, does it? I was just rereading this as part of the edit. But service programs are definitely worth doing. Just keep things as simple as you can.

What Ya Shoulda Learned

As in the previous chapter, our recap is pretty straightforward.

First, you should be able to describe the difference between (or what each one does) both binding language and binding directories.

Second, you should know where both of these entities are kept. That is, are they a command that creates an object, or a source file that contains instructions, or what?

Third, can you remember some of the source/command verbiage that you would have to use?

Fourth, do you remember how each one is used? That is, what its purpose is?

And finally, were you able to stay awake during the discussion of how binding language, if not used correctly, can result in the wrong sub-procedure being called? Granted, it is not the normal situation, and it won’t happen every day, but it could happen, so be careful.

 

 

 

David Shirey

David Shirey is president of Shirey Consulting Services, providing technical and business consulting services for the IBM i world. Among the services provided are IBM i technical support, including application design and programming services, ERP installation and support, and EDI setup and maintenance. With experience in a wide range of industries (food and beverage to electronics to hard manufacturing to drugs--the legal kind--to medical devices to fulfillment houses) and a wide range of business sizes served (from very large, like Fresh Express, to much smaller, like Labconco), SCS has the knowledge and experience to assist with your technical or business issues. You may contact Dave by email at This email address is being protected from spambots. You need JavaScript enabled to view it. or by phone at (616) 304-2466.


MC Press books written by David Shirey available now on the MC Press Bookstore.

21st Century RPG: /Free, ILE, and MVC 21st Century RPG: /Free, ILE, and MVC
Boost your productivity, modernize your applications, and upgrade your skills with these powerful coding methods.
List Price $69.95

Now On Sale

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: