Programming

Practical RPG: Data in the Cloud, Part 2

Wed, 05 Mar 2014 06:00:15 +0100

The cloud has successfully provided file storage since long before it was called the cloud, but does that success translate to databases? Written by Joe Pluta In my previous article, I introduced you to the concept of files in the cloud, whether it's a file-sharing service such as Dropbox or a whole-enterprise backup system using something like Carbonite or CrashPlan. But in this article, I want to focus on a relative newcomer to the playing field, databases in the cloud. These are true relatio...

Can an ILE CL Program Know the Number of Parameters Passed to It?

Wed, 05 Mar 2014 06:00:10 +0100

Investigate the ILE CL compiler's mechanism for receiving program parameters. Written by Junlei Li There's no doubt that the program-call mechanism in IBM i is fully dynamic. The called program can be determined at run time instead of at compile time. The parameter list passed to the called program can be composed at run time by the calling program. Also, the length of the parameter list for a called program can be changed dynamically. As you might know, an ILE RPG program can retrieve ...

RPG Academy: Binding It All Together

Fri, 28 Feb 2014 06:00:15 +0100

The previous TechTip of this series explains the module, program, and service program concepts. It's now time to learn how to create these objects and to find out a bit more about binding directories. Written by Rafael Victória-Pereira Creating an OPM RPG program is an easy, one-step operation: Just type "14" in the respective source member line of the Work with Members Using PDM screen and you're done. Creating an RPG ILE program requires a few more steps, but it doesn't have to be hard. ...

More Free-Form for RPG

Wed, 19 Feb 2014 06:00:20 +0100

Heard about the new positionless RPG support that's coming out for V7.1? No? OK, then have you heard about Pluto? That's messed up. But we're going to focus on just the former. Written by David Shirey If you're not already using positionless RPG, the so-called RPG /free, then what are you waiting for? It's easy to learn, and just the ability to indent and re-indent (which makes it so much easier to see the structure and flow of your program) is enough to make you switch from COPR (Crappy Old P...

The API Corner: Determining How Many and What Jobs Are Currently Active

Wed, 19 Feb 2014 06:00:15 +0100

Today, we'll extend our API suite using the List Jobs System API. Written by Bruce Vining In the last API Corner article, "Determining Whether Jobs Are Currently Active," we created the service program (*SRVPGM) JOBCHKS. The *SRVPGM exported the function JobActive, which defined one input parameter and returned an indicator. The input parameter could be a simple job name such as DAYEND, a generic job name such as DAYEND*, or a special value such as *CURRENT. If one or more jobs with the specifi...

Test-Driven PHP Development

Wed, 12 Feb 2014 06:00:15 +0100

It's a new way of looking at an old problem. Written by Kevin Schroeder Editor's note: This article is an excerpt from the new book Advanced Guide to PHP on IBM i. Have you ever run into a situation where you built something or made a change somewhere only to have it break something else? If your answer is no, wait until you graduate and get a job. It is bound to happen, and sometimes it will happen with catastrophic effects. Part of the problem is that we do not often test o...

RPG Academy: Modules, Programs, and Service Programs

Fri, 07 Feb 2014 06:00:15 +0100

The first step of the journey from OPM to ILE is getting a grasp on the foundational concepts of ILE. This TechTip explains how the module, program, and service program concepts relate to OPM's program concept. Written by Rafael Victória-Pereira How do you create an OPM RPG program? You write your source, compile it with PDM's option 14, and (after you squashed all those annoying little bugs) you get a *PGM object. To create an ILE program, the steps are similar: you compile your source not in...

Book Review: Developing Web 2.0 Applications with EGL for IBM i

Fri, 07 Feb 2014 06:00:10 +0100

It's everything you need to know, from the bottom up. Written by Mike Myers Let me first explain a little about myself. I wrote my first program in 1982 on a System/34 (RPG II). Two years later, I was on the System/38 (RPG III), and soon after, the AS/400 (RPG IV, etc.). So, yes, I am an old green-screen developer—working hard, I might add, to update my skill set using Rational Developer for i for SOA Construction (RDi SOA). I found Joe's book very useful in introducing me to the key...

Practical RPG: More BIFs

Wed, 05 Feb 2014 06:00:15 +0100

Built-in functions (BIFs) are powerful on their own, but together they can perform some fantastic feats! Written by Joe Pluta In a previous article, we touched on how we can use built-in functions (BIFs) in I/O operations, a subtle but potent result of the syntactical enhancements in RPG. Using BIFs (and other expressions) in I/O operations reduces code complexity by removing work variables. Another way to reduce code complexity is just to remove lines of code. This article provides an exam...

Discover the Suspend Object (SUSOBJ) MI Instruction

Wed, 05 Feb 2014 06:00:10 +0100

What can you do with it? Let's try some experiments and see. Written by Junlei Li In the EPA Headers section of chapter 8, Objects, of his famous book, Fortress Rochester, Dr. Frank Soltis mentions that there's an object-suspended state flag in the attribute byte (the first byte) of the Encapsulated Program Architecture (EPA) header of each MI object. As you might know, the attribute byte of an MI object's EPA header contains the most critical attributes of the MI object. So when should an MI o...

Book Review: Advanced Integrated RPG

Fri, 31 Jan 2014 06:00:10 +0100

Isn't it about time somebody told us how to integrate RPG and Java? Written by Joe Pluta Tom Snyder's first foray into RPG programming books, Advanced Integrated RPG, is an auspicious beginning. The book is ostensibly about three specific examples of integration between RPG and Java: accessing Excel spreadsheets, creating PDF documents, and sending email. And while the book presents these topics quite well, it's the larger view of the book that really makes it special....

Book Review: Java for RPG Programmers

Fri, 17 Jan 2014 06:00:10 +0100

If you've been putting off learning Java, you have no excuse anymore! Written by Joe Pluta Java for RPG Programmers has been popular for over a decade. This unique book manages to bridge the gap between the procedural nature of RPG and the sometimes mysterious world of Java and object-oriented programming (OOP). This Third Edition is a worthy entry in the book's history. The problem for RPG programmers is that most Java books don't differentiate between application programming and...

The Future of RPG

Wed, 15 Jan 2014 06:00:15 +0100

Much like COBOL, RPG isn't going away any time soon, so let's see if we can get some new features! Written by Joe Pluta Many of us in the industry have been working with RPG for 30 or more years. We can remember back to the time when the CALL opcode was added, which changed the language forever. Now, RPG is as full-featured a language as any out there and includes the still unparalleled direct access to the database that makes RPG programs run rings around any other programming environment....

Simon's Solutions: Talk with REXX Programs

Wed, 15 Jan 2014 06:00:10 +0100

Learn how to exchange data with REXX programs via the REXX external data queue. Written by Junlei Li During the years in which Simon Coulter posted on the midrange.com forums, he taught the IBM i community a lot about the REstructured eXtended eXecutor (REXX) language. For example, in the following post in the RPG400-L mailing list, Simon demonstrated the simplicity and ease of use of this powerful scripting language vividly via a couple of interesting example Rexx programs....

Book Review: The Remote System Explorer

Fri, 10 Jan 2014 06:00:10 +0100

This book speaks directly to the thousands of IBM i programmers who develop in RPG, COBOL, CL, and DDS every day. Written by Susan Gantner Whether you're an RSE neophyte, an experienced RSE user, or still a dyed-in-the-wool SEU user wondering if there's a better way, you should read this book. It does an excellent job of covering the basics while still offering many tips and details beyond the basics that even I didn't know--despite having used RSE for years. The authors--Don Yantzi an...

Book Review: IBM System i APIs at Work, Second Edition

Fri, 03 Jan 2014 06:00:10 +0100

API expert Bruce Vining delivers the only comprehensive guide to APIs. Written by Jon Paris Although I have rarely had problems using the C-style APIs from RPG, for some strange reason, the system APIs have always intimidated me. Perhaps it is the arcane terminology that IBM uses to describe them. Perhaps it is the lack of good RPG examples in the manuals. Or perhaps I'm simply API-phobic. Whatever the reason, I have often turned to the experts when I needed to use an API. During my time with I...

Book Review: Subfiles in Free-Format RPG

Fri, 20 Dec 2013 06:00:10 +0100

Whether you're a newbie or a seasoned pro, this book has something for you. Written by Mike Faust For System i developers, mastering the ability to develop subfile applications is an absolute must! In Subfiles in Free-Format RPG, Kevin Vandever takes the reader through the subfile concept—from start to finish. Unlike other books on the topic, this one specifically focuses on coding subfile applications in free-format RPG and does an excellent job of explaining how to use subfiles in the moder...

What Everyone Should Know: Where to Start

Wed, 18 Dec 2013 06:00:15 +0100

website website http://shireyllc.com/IBM%20i.html There's so much to learn today, and the "to learn" pile just keeps getting bigger and bigger while our time to learn it seems to shrink. So what's a body to do? Written by David Shirey Do you ever feel depressed? Professionally that is? Like there is so much to learn and there is no way you're going to be able to squeeze it into your already overloaded day? Yeah, me too, and I am easily depressed to begin with, so it wreaks...

The API Corner: Determining Whether Jobs Are Currently Active

Wed, 18 Dec 2013 06:00:10 +0100

Build your own API using the List Jobs System API. Written by Bruce Vining I was recently asked by Mark H. if there's an easy way to determine whether a given job, using only a simple job name such as DAYEND rather than a qualified job name such as 123456/ABC/DAYEND, was currently active on the system. From my point of view, it's easy enough to call some system APIs to determine this, but he would prefer for application developers to just make a simple call to a function that, at a mini...

Using ASNA Mobile RPG to Create a Mobile App

Wed, 18 Dec 2013 06:00:05 +0100

ASNA Mobile RPG puts mobile programming capabilities easily in the hands of RPG programmers using nothing but RPG! Written by Roger Pence ASNA Mobile RPG is a product that empowers RPG programmers to create great mobile apps for smartphones and tablets using only RPG. There's no need for JavaScript, HTML, Objective C, Java, PHP, or any of the other languages typically used for mobile development. One of the hallmarks of great mobile applications is that they are able to ...

Book Review: Functions in Free-Format RPG IV

Fri, 13 Dec 2013 06:00:15 +0100

This one short volume manages to essentially be both a general introduction and a detailed reference. Written by Joe Pluta With Functions in Free-Format RPG IV, Jim Martin has done it again. Jim has a particular expertise in taking a highly technical topic and distilling it into just a couple of hundred pages, making it accessible to any IBM i programmer. Jim also has a knack for identifying just the right balance of general knowledge and technical detail, and this book demonstrates that sense ...

Practical RPG: Data in the Cloud, Part 1

Wed, 04 Dec 2013 06:00:15 +0100

The cloud has become ever more ubiquitous, but with so many choices it's hard to know what fits your business; this article will help you begin to sort through things. Written by Joe Pluta Cloud-based data is a huge topic. Nowadays, you can find everything in the cloud, from simple file storage to entire applications. Software-as-a-service (SAAS) has mushroomed and morphed into a plethora of virtual services. The problem with such a variety is trying to identify which services and provi...

Investigate the Undocumented _LSPCO System Built-in

Wed, 04 Dec 2013 06:00:10 +0100

The _LSPCO system built-in accepts a space pointer as its input and returns the origin of addressable storage of the "space" addressed by the space pointer. Written by Junlei Li In my previous article, A More Complete View of the Machine Interface of IBM i, I introduced a technique that Gene Gaunt invented to retrieve all system built-ins supported by an IBM i release. You might have noticed that many of the system built-ins retrieved via Gene's technique have never been documented publ...

PHP: Variables, Arrays, and Functions: The Final Chapter

Wed, 20 Nov 2013 06:00:15 +0100

This is the last step in understanding how variables, arrays, and functions are similar, are different, and come together to form the basis of the PHP universe. Written by David Shirey So far in this series, we have covered variables and arrays. Granted, it took us three months to cover arrays and how to display them, but let's not worry about that now. In the process, we saw that variables were preceded by a dollar sign ($) and consisted of underscores plus any alphanumeric digits (that i...

The API Corner: Verifying That Nothing Has Changed, Part 2

Wed, 20 Nov 2013 06:00:10 +0100

Explore more options with the Calculate Hash API. Written by Bruce Vining Last month, in Verifying That Nothing Has Changed, we saw how easy it can be to create a hash over a string such as 'Some data to be hashed' by using the Calculate Hash API. We also saw how the calculated hash value is very dependent on what data is being hashed. Something as simple as a trailing blank or a punctuation change can cause significant changes in the derived hash value. Today, we'll look at some options on how...

Application Lifecycle Management: Some Definitions (and Misconceptions)

Mon, 11 Nov 2013 06:00:15 +0100

Integrated Application Lifecycle Management (ALM) provides the ability to innovate while reducing overhead costs, thus improving time to delivery, quality, value, and predictability. Written by Olenka Van Schendel The classic definition of Application Lifecycle Management (ALM) derives from the notion of "software as a product": identifying distinct and cyclical phases of requirements management, software architecture, development, testing, maintenance, change management, project management, a...

Practical RPG: Technology Refresh 7 First Look

Wed, 06 Nov 2013 06:00:15 +0100

Technology Refresh 7 (TR7) provides quite a few new features, and this is the first article devoted to some of those changes. Written by Joe Pluta TR7 has a wealth of additional features and functionality for various parts of the IBM i operating system, and in coming articles I plan to cover as many of them as possible. But since the focus of today's article is RPG, it makes sense to stick with the enhancements in RPG-related compilers. So let's take a look at what has happened....

Manage Automatic Storage Dynamically via Modify Automatic Storage Allocation (MODASA)

Wed, 06 Nov 2013 06:00:10 +0100

Learn the fantastic automatic storage frame (ASF)-operating MI instruction and the implementation details behind it. Written by Junlei Li From the point of view of a programmer, the ability to change the automatic storage allocation at run time would be fabulous. Automatic storage is thread-private storage; therefore, in a multi-threaded environment you don't need to worry about thread synchronization when you store your program variables in automatic storage. Automatic storage is managed by th...

PHP: Variables, Arrays, and Functions, Part 3

Wed, 16 Oct 2013 06:00:15 +0100

Use the foreach PHP command to get data out of a mult-dimensional array. Written by David Shirey We're going to do one last piece related to arrays in PHP. Why? Because when you're using PHP to put data out onto a page or read data in from a page, you'll use arrays as the intermediary between your file and your page. Consequently, knowing how to deal with them is very important....

The API Corner: Verifying That Nothing Has Changed

Wed, 16 Oct 2013 06:00:10 +0100

Learn what the Calculate Hash API can do for you. Written by Bruce Vining In the past month, I've been asked two related questions. The first was "Can my AS/400 [sic] work with hashes?" and the second, a bit more specific, "Can the i generate a SHA-256 hash to work with a Linux system?" The answer to both questions, as you might expect, is yes, there's an API for that (as long as the system is at V5R3 or higher that is, in the case of the AS/400 question)....

Practical RPG: BIFs and Expressions

Wed, 02 Oct 2013 06:00:15 +0100

Built-in functions (BIFs) allow you to significantly reduce the maintenance code in programs; here's an example. Written by Joe Pluta Built-in functions (BIFs) are designed to make programmers more productive. They do this in a number of ways, but one my favorites is how they reduce the number of lines of code in my programs. If you've used BIFs you're probably already familiar with how they simplify your code; for example, date manipulation is far simpler using the %date BIFs. Today, though, I...

A More Complete View of the Machine Interface of IBM i

Wed, 02 Oct 2013 06:00:10 +0100

Learn a creative technique that Gene Gaunt invented to retrieve all system built-ins supported by your IBM i. Written by Junlei Li Since System/38, as a high-level machine interface, the Original Machine Interface (OMI) instruction set described a complete, elegant object-based architecture of the system. The OMI instruction stream, along with other components (e.g., the object definition table (ODT)) stored in the program template of an MI program object, allows the MI program to be translated...

PHP: Variables, Arrays, and Functions, Part 2

Wed, 18 Sep 2013 06:00:15 +0100

Love the idea of putting data in two-dimensional arrays? Well, the next step is figuring out how to get it out. But before you do that, there's one little thing. Written by David Shirey In our last visit, we talked about arrays. We talked about the difference between numeric and associative arrays. We talked about how to load and unload data from them. And we talked about how to load data into two-dimensional associative arrays, which more or less mimic file records. Let's face it, we just co...

The API Corner: Manipulating a Job's Library List

Wed, 18 Sep 2013 06:00:10 +0100

Learn what the Change Library List API can do for you. Written by Bruce Vining I recently received a note from Shawn W. related to a situation in which he needs to significantly change a job's library list, perform a function, and then restore the job's library list to the original values. In his case, a corporation on one System i might have multiple instances of an entity (multiple plants, multiple companies, etc.) with each entity having multiple libraries associated with it (inventory libra...

Practical SQL: Variables in SQL

Wed, 04 Sep 2013 06:00:15 +0100

One problem with complex queries is keeping all the pieces in sync; this technique helps you do just that. Written by Joe Pluta I've long extolled the virtues of common table expressions (or CTEs), and I've also showed you how to use UNION statements to great advantage. They're powerful, and I find them particularly well suited to performing ad hoc analysis on production data. Unfortunately, both of those techniques can fall prey to a very specific problem that has caused me severe headaches in...

Genuine Dynamic Program-Exported External Data in IBM i

Wed, 04 Sep 2013 06:00:10 +0100

Learn the native dynamic external data mechanism we have had since System/38. Written by Junlei Li As an IBM i developer, you might be proud of the numerous dynamic features in either the OS level or the machine interface (MI) level that allow our developers to produce more reliable and maintainable software products with less effort. For example, the Override commands allow programmers to override (replace) a file that is used by a program or override certain parameters of the file being proce...

What You Should Know About the Format of Records Saved to a Save File, Part 2

Wed, 21 Aug 2013 06:00:15 +0100

Do you need to retrieve data from variable-length fields of deleted records? Written by Juan Macias The data of variable-length fields of records deleted from a file can be retrieved provided that the inserts and updates performed in the file after the records were deleted didn't affect the variable part of the file....

The API Corner: Accessing Job Queue Entries

Wed, 21 Aug 2013 06:00:10 +0100

Use the Open List of Jobs API. Written by Bruce Vining In last month's column, "Monitoring a Job Queue from an RPG Application Program," we looked at how an application program could be notified, via data queue messages to a user-specified data queue such as BVINING/MYDTAQ, when a job is submitted to a job queue such as BVINING/MYJOBQ....

The Perils of Activation Groups Gone Awry

Wed, 07 Aug 2013 06:00:15 +0100

Controversy surrounds the use of service programs in the default activation group, and this article explains a very specific and painful reason to avoid it. Written by Joe Pluta You've probably heard that programs written for the Integrated Language Environment (ILE) don't work and play well with legacy programs written using the Old Program Model (OPM). And if you're like me, you've probably tried them together to see what would happen. This isn't something we do cavalierly; instead, it's usua...

1001 Activation Groups Within a Single Job

Wed, 07 Aug 2013 06:00:10 +0100

The solution revealed in this article allows you to start user-defined activation groups and run programs in them. Written by Junlei Li Have you seen an IBM i job containing more than 1000 activation groups? If not, you can call the following seven-line CL program (agp1001.clp) in an interactive job and then issue a DSPJOB OPTION(*ACTGRP) command to check what you get....

PHP: Variables, Arrays, and Functions (Don't Say It)

Wed, 17 Jul 2013 06:00:15 +0100

You've used arrays in RPG, but they're so much more important in PHP. Written by David Shirey Last May, we talked about variables and how they're used in PHP. If you were paying any attention, which I wasn't, you know that PHP supports the following variable types: string (alphanumeric), integer, floating point (decimals), Boolean (true or false), array, object, null, and resource. Now we want to zero in on one of those variable types that we talked about—namely, arrays—and look at how they...

The API Corner: Monitoring a Job Queue from an RPG Application Program

Wed, 17 Jul 2013 06:00:10 +0100

Today, we'll look at using the Job Notification Exit Point. Written by Bruce Vining In last month's column, "Monitoring a Job Queue," we looked at a CL program that, via data queue messages sent by the system, enabled us to become aware of newly submitted jobs to a job queue and automate the release of those jobs. This month, we'll provide that level of automation, and a bit more, using an RPG program....

Practical SQL: OLAP, Part 2

Wed, 03 Jul 2013 06:00:15 +0100

In this next installment on SQL's Online Analytical Processing (OLAP) functions, you'll see how OLAP continues to provide SQL users the business functions we've enjoyed in RPG for so long. Written by Joe Pluta In my previous OLAP article, I used the OLAP function ROW_NUMBER to provide the concept of "next record" that we take for granted in RPG's native access (contrast RPG's native ISAM access with SQL's relational access). In this article, I'll show you the magic of GROUPING SETS and how they...

Change the Last-Used Date of an IBM i System Object Arbitrarily

Wed, 03 Jul 2013 06:00:10 +0100

A practical tool program can achieve that goal. Written by Junlei Li When issuing a DSPOBJD DETAIL(*FULL) command on an IBM i object, you might have noticed the Last used date field in the Change/Usage Information portion of the result display. As its name indicates, the Last used date attribute is the date on which the object was used the last time. As you probably know, the last-used date attribute is not stored in the Object Information Repository (OIR) space of the context in which the obje...

The Once and Future PHP

Mon, 24 Jun 2013 06:00:15 +0100

Where has PHP been, where is it now, and where is it going? Written by Thomas M. Stockwell PHP, the incredibly popular server-side scripting language originally created by Rasmus Lerdorf in 1995, has become one of the greatest success stories of the open-source software movement. Today, PHP is estimated to be installed on millions of web servers worldwide, fueling an estimated 244 million websites. Some analysts claim that over 90% of the Internet is enabled by PHP scripts. Yet, ironically,...

Storing Metadata the Profound UI Way

Mon, 24 Jun 2013 06:00:10 +0100

Discover the benefits of using RPG OA and JSON to store metadata in the display file. Written by Scott Klement Editor's note: This article introduces the white paper "Storing Metadata the Profound UI Way" available free from the MC White Paper Center. While RPG Open Access is nothing new, there's still some confusion in the IBM i community as to what it is and how it's used. Additionally, there has also been much talk lately about Open Access metadata and how it should be leveraged wi...

Cool Things: ILE RPG as a Web Services Client

Fri, 21 Jun 2013 06:00:15 +0100

Use IBM's Web Services Client for ILE to consume a web service in an ILE RPG program. Written by Mike Faust Web services serve many purposes—from utilizing external web services for things like retrieving exchange rates or tracking shipments, to using internal web services as a means of communicating between applications within your organization. The task of writing a program to consume a web service can be relatively simple or very complicated, depending on the requirements of the web servic...

The API Corner: Monitoring a Job Queue

Wed, 19 Jun 2013 06:00:15 +0100

Learn the value of using the Job Notification Exit Point. Written by Bruce Vining Back in April, the following question was posed on the MC Press Online CL forum: "I am looking for advice on how to create a CL that will actively monitor a specific job queue and release jobs. All jobs that are submitted automatically go to hold status because the JOBD for end users is set to this. The business does not want to change the JOBD, so I need to come up with a way to actively monitor jobs for...

RPG IV Style: Free-Format Syntax

Wed, 19 Jun 2013 06:00:10 +0100

If you use the free-format specification, good standards will result automatically. Written by Bryan Meyers and Jim Buck Editor's Note: This article is an excerpt from the book Programming in RPG IV, 4th Edition. At current releases, RPG IV is primarily a free-format language, especially in the area of calculation processing. While it's not perfect, the free-format specification effectively renders the traditional fixed-format Calculation specification obsolete. IBM has introduced many ne...

Introduction to SQL, Part 5

Wed, 12 Jun 2013 06:00:15 +0100

Editor's note: This article is an excerpt from Mastering IBM i, published by MC Press. Written by James Buck and Jerry Fottral An additional feature of the Run SQL Scripts interface is SQL Assist. This feature allows the user to create fairly sophisticated SQL statements with little or no knowledge of SQL. Although you should learn to write SQL statements without depending on a feature such as SQL Assist, this is a great tool to help you, as a new SQL programmer, to develop SQL statements while...