I found it very difficult to get the learning process started and the thing which I found most difficult around this was getting hold of the right materials to understand things. Unlike Java, C# or any of the other programming languages which are relatively more popular compared to RPG or CLP, the internet does not have much to offer as far the iSeries is concerned. There are IBM Redbooks but hey, lets face the truth! : Redbooks from IBM might not be very easy to comprehend (this is strictly a personal opinion).
What you would find more helpful are books written in a more structured manner with examples that one can relate to.
Now it took me a while to figure out the right books and I have listed them below to ease the pain of researching the right material:
CL Programming: Complete CL by Ted Hold
RPG Programming:Programming in RPG-IV by by
Subfiles: Subfiles in Free-Format RPG: Rules, Examples, Techniques, and Other Cool Stuff by Kevin Vandever
ILE Concepts: Functions in Free-format RPG IV by Jim Martin
SQL: SQL for eServer I5 and iSeries by
These books are a great way to get started and pretty much covers what I believe are the “Core” concepts an iSeries programmer should be good at.
Now another challenge is the high cost of these books (atleast from an indian point of view). I never bought any of these and had made use of copies available in my office library.
The Fortress Platform :) 