Sat, Jun
4 New Articles

AS/400 Stored Procedures to the Rescue!

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

Recently, I completed a really large e-commerce site for one of my clients that taught me a few things I didn’t know about the AS/400. The challenge to my latest project was that I had to interface with a legacy system written in RPG III that has been around since the System/38. You know the kind of code. Just keep shoveling on functionality and never do a total rewrite. Not that that’s bad; in fact, it’s how we end up with fantastic legacy systems. Like fine scotch whiskey, legacy apps take time to fully mature into those killer applications. But did you know that all of the RPG III code is just as reusable as ILE C, RPG IV, and all these other highfalutin technologies that IBM has on the 400? Read on for the magic of stored procedures and how they saved my posterior.

The victim application is a distribution system that tracks inventory, lets people enter orders, and does accounting for a large company with 85 branch locations and a humongous warehouse. My job, like the prime directive in Star Trek, was noninterference with the native populace. In English, do no harm to the application layer, but place a Web interface for customers to reprint invoices, check stock status, order parts, and manage their accounts on top of that beast. Simple for SQL Dude, especially since the client had all of the source code, right?

Yes, to my amazement it was really simple, because the code and data was on the AS/400.

Why was it easy? First, a little background info. The systems architecture was probably like a lot of legacy 400 systems. The order entry program consisted of 25,000 lines of RPG III code with embedded presentation logic. However, the programmers had taken some of the application logic and put it into separate programs to make the application somewhat simpler and probably to gain some code reuse. For example, the code that calculated the price of a part for a specific customer was a separate RPG program that was called within the order entry program. Pass it the customer and part numbers and associated factors like the job number and phase of the moon and, whoosh, out comes the price for that customer at that moment in time. Thank goodness it was a separate program, as I have never seen a more Byzantine pricing program in my life. If I had to replicate the program logic myself, I would have been at the customer’s site till St. Swithun’s Day.

Another potential problem was all of the hairy tax calculations that are dependent on where a customer is and where the part is shipping from, especially if the customer is in a different country. Those RPG III guys saved my bacon, as the tax calculations were in a

separate program that was called with a parameter list and the tax charges returned in the list of parameters.

The system I created was built using Microsoft Internet Information Server (IIS) on an NT Server. It used Active Server Pages (ASPs) written in VBScript along with a few Component Object Model (COM) objects. When my ASP programs or COM objects needed a part price for a specific customer, I just called an AS/400 stored procedure that allowed me to use the RPG pricing program. Bam!

I didn’t have to rewrite the application logic; I got to reuse it in my Web pages. Again, when I was processing an order and needed to find out how much the Canadian government needed to be sent on behalf of my client, stored procedures allowed me to reuse the legacy code. Finally, when my order was processed and I needed to print a pick ticket, I just called the appropriate RPG III program via SQL and the ticket magically printed at the proper branch location.

The beauty of the whole approach is that I wrote only a single CREATE PROCEDURE statement for each RPG III program that I wanted to call. The CREATE PROCEDURE statement identifies the program I want to call, the parameters that are expected, and the language of the program. Once this statement is executed, and it is only executed once, the legacy program is available to me via an SQL CALL statement. And note that these programs I was calling are RPG III programs, not ILE C or RPG IV. I left the legacy code as it was and invoked its important logic from another platform to do my bidding. Again, I want to emphasize that there was no recompilation of the RPG III code, no complicated wrapper program, and no need for Java servlets or ILE service programs.

I just used the built-in facilities of the AS/400 and its amazing support for SQL standards. Now the application logic is available to any program on any platform that supports SQL. Yes, Virginia, there is a Santa Claus, and his name is AS/400.

Using stored procedures is the best way to leave the business logic where it belongs and let you place the presentation layer somewhere else. That somewhere else can be an RPG program with DDS, a VB program on a PC, or a Java servlet using WebSphere. You probably do not have to redesign and recode your legacy applications as much as you might think to make them Web available and presentation-layer independent. Some small redesign may be necessary, but overall, that would just make your code more reusable and less complicated from a management standpoint by separating the logical functions of the code into separate programs. I’m sure that if you take a look at your legacy code, you can find procedures waiting to be called.



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: