• Guru: Beware of SQL Precompiler Variables

  September 26, 2022 Ted Holt

  In a famous Henny Youngman joke, a patient says, “Doctor, it hurts when I do this,” to which the doctor replies, “Then don’t do that.” Corny jokes aside, I have spent decades trying to identify programming practices that hurt when I do them, and having identified them, cease to do them. A case in point is the misuse of the variables that the SQL precompiler defines in my RPG programs, variables such as SQLCODE, SQLSTATE, and SQLER3.

  “So what,” I hear you ask, “is the problem with these variables? ” Well, they’re global, and global variables are evil.   Global …

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• Guru: The SND-MSG Op Code And Message Subfiles

  September 12, 2022 Ted Holt

  If you’re one of the many IBM i programmers who still writes green-screen applications, think about how your programs communicate with the users. How do you tell a user that a value that he’s just entered is invalid, or that he needs to press a command key to proceed? I’ve seen several methods, but a common one — and my favorite — is to communicate through a message subfile.

  The nice thing about message subfiles is that I can report two or more messages at one time. I like the computer to find as many errors as possible and let …

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• Guru: Regular Expressions, Part 2

  August 15, 2022 Mike Larsen

  In the first part of this series, I showed how to replace characters in a string using SQL and regular expressions. This time, I’ll show other regular expressions that are available for us to use. The regular expression functions I’ll show are REGEXP_COUNT and REGEXP_LIKE and the examples come from production programs that I’ve recently implemented.

  In the first example (Figure 1), I want to get a count of the number of occurrences of a pattern within a string. To make this more interesting, I’m searching for two different patterns within a sting. To accomplish this objective, I used …

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• Guru: IBM i Privileged Account Management, And What’s So Special About Special Authorities

  August 1, 2022 Bruce Bading

  Privileged Account Management (PAM) is a keystone of cybersecurity. Everywhere we look PAM is a hot topic. How and why should we worry about it? IBM, Ponemon, Verizon, etc., tell you that it is vitally important to protect your endpoints from cyberattacks and insider threats. While the Verizon DBIR states that external threats account for 80 percent of security incidents, it points out their findings that show otherwise for incidents resulting in data compromise where the insider threat exceeded that of an outsider by more than 10 to one. Simply put by Verizon, “This supports the principle that …

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• Guru: Regular Expressions, Part 1

  July 25, 2022 Mike Larsen

  In the first part of this series, I will show how to replace characters in a string using SQL and regular expressions. I know I can replace characters using RPG or SQL, and they work great, but there are some cases where I find using regular expressions is a bit easier.

  For the examples I’ll show, I’m using the REGEXP_REPLACE function. REGEXP_REPLACE allows me to search for a particular value within a string and replace it with another value.

  In the first example (Figure 1), I want to search a string that has both letters and digits and I want …

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• Guru: IBM i Experience Sharing, Case 5 – Using IBM i PDI Charts To Answer Performance Questions

  July 18, 2022 Satid Singkorapoom

  During my long career as an IBM i performance specialist, it was natural for people to ask me performance-related questions of various kinds. But in many cases, it seemed to me that the customer could not understand my answers, and I could not provide supporting evidence due to the lack of a performance reporting tool that could produce easy-to-understand explanatory information. The situation changed for the better with the availability of IBM i Performance Data Investigator (PDI) tool as of release 6.1. I would say that the PDI tool provides charts of information that resemble those used by business people …

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• Reader Feedback On Guru: The Finer Points of Exit Points

  July 12, 2022 Bruce Bading

  Hey, Alex:

  Hope you are doing well. I was reading this article about exit points and found some technical inaccuracies.

  The Socket Exit can be used to cover the following: You can use exits block all unwanted ports blocked. I will be happy to talk with author of this article to explain how this works.

  • Not all services have exit points available.
  • User defined ports do not have exit points associated.

  Best regards,

  — Tony Perera, Trinity Guard, a division of Fresche Solutions

  ---

  Hey, one and all:

  As the article states, exit points are an enhancement to cybersecurity on the …

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• Guru: The Finer Points of Exit Points

  June 27, 2022 Bruce Bading

  Many years ago, we received a call from an IBM i customer stating that all exit points were gone and the QAUDJRN and receivers were missing. Then the question, “Do you think we’ve been hacked?” Truth was, the exit points weren’t gone; the associated programs had been de-registered. Conclusion, they had most likely been compromised.

  The IBM i platform is a very securable system that can be secured (Secure vs Secured – What’s the difference?, WikiDiff), if you take steps to secure it.

  On the IBM i, a limited number of functions provide an exit so that your …

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• Guru: The CALL I’ve Been Waiting For

  June 20, 2022 Ted Holt

  Christmas came to my house early this year. May 3, to be exact. Boy! Was Santa Claus good to me! IBM gave me two presents! The first was a CL enhancement that I had desired for years. The second was an improvement that, to my delight, almost obsoletes a utility I wrote years ago. Both have to do with the CL CALL command.

  CALL is arguably the most used and most important command in CL, yet for all these years it has remained untouched. I’m glad that IBM has seen fit to devote time and resources to the enhancement of …

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• Guru: IBM i Experience Sharing Case 4 – Investigating Time-Sensitive Transaction Issues

  June 6, 2022 Satid Singkorapoom

  Among the central processing hardware resources in a computer system – CPU, GPU, memory, disk, PCI-Express I/O bus – disk has always been the slowest component. Even the latest flash disk or NVM-Express flash drive or card is slowest, but not by much. Back in the days of hard disk, disk I/O was the most popular cause of performance problems. From experience, I always looked at it first in my investigation.

  The modern SAN flash disk can still be the performance bottleneck when it is not deployed properly, as I shared in Guru: IBM i Experience Sharing, Case 3 – …

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