Exploring RPG and Ext JS

Taking applications to the next level while leveraging existing applications

Taking applications to the next level while leveraging existing applications

I’ve long been in search of the next solid UI that RPG programmers can safely adopt and count on to serve us for the next 10 to 15 years. The IT industry as a whole seems to be suffering from a UI identity crisis—nobody can find the right approach that works well in many situations. UIs like Adobe’s Flex technology ( are very appealing to the eye, but they quickly start falling apart when you realize very little forethought went into them for long-term adoption. For example, with the Flex approach, screens are “compiled” and then sent to each client. If a screen changes, a new compiled object must be downloaded to the client. Think of this as similar to downloading all *DSPF objects to a client PC before it could run the application. It’d be a maintenance nightmare in traditional homegrown applications where hundreds (if not thousands) of screens represent the back-office application.

Because technologies like Adobe Flex, Microsoft Silverlight ( and JavaFX ( all have their challenges, I’ve ventured into the more traditional, less proprietary approach of HTML, JavaScript* and cascading style sheets (CSS) because they send the screen representation down from the server each time with a much smaller footprint. Of the many frameworks that support those technologies, Ext JS currently leads the pack.

Ext JS ( is, in part, a set of out-of-the-box UI components that can be used to create rich Internet applications. Components include input boxes, buttons, grids of data, tabbed panes and so on. The Ext JS products page ( shows the many UI components Ext JS supports.

Before you ask “What does this have to do with me, an underappreciated RPG programmer?” let me say I want RPG programmers to be appreciated again and much depends on us becoming well-versed in how to take our applications to the next level while leveraging the existing investment our organizations have made in RPG, DB2* and IBM i. The reality is that Ext JS, while probably not the end-all UI framework of today or the future, can provide substantial reason to keep all business logic and corresponding programming on the IBM i instead of going to Microsoft* or Java*. With that said, I want to give you a jump start with Ext JS as it relates to RPG, and the best way to do that is dive in and learn how all of the pieces fit together.

I’m forever looking for patterns in my code to see how I can lessen complexity and automate where possible.

Aaron Bartell is Director of IBM i Innovation for Krengel Technology Inc. and an IBM Champion.

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