System i Addict

IT Jungle has the post. It’s a very god read. Hope to get more details on this so we can all understand it.

Without getting too technical, here’s what happens on the OS/400 and i5/OS platform when you create applications, which explains the problem customers ran into in 1995 and which IBM wants them to avoid in 2008. A programmer writes an application in say, RPG. They run it through a compiler, either using the Original Program Model (OPM) or the Integrated Language Environment (ILE) compilers, and the code compiles so they can run it. Or, rather, that is what it looks like to the programmer. What is really happening is that this application is compiled into an intermediate stage, which some IBMers have called RPG templates (in the case of RPG applications). These templates have a property called observability, which in essence means they are compiled to the TIMI layer. These intermediate templates are then used by the TIMI layer on an actual piece of hardware with a specific processor and instruction set to compile the application to run on that specific processor. TIMI compiles these RPG templates down to actual compiled code behind the scenes the first time an application runs, and because the code was originally compiled to the TIMI layer, there is no need to change the source code. Only the object code changes, which end users never had access to anyway because only TIMI can reach down there. This is the brilliant way that IBM has preserved customers’ vast investments in RPG, COBOL, and other applications over the years.

The entire story here… 

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