ISeries 101

People who move to the 400 from other computing environments and backgrounds have some common areas of misconceptions and concepts difficult to grasp at first. Understanding these problem areas can assist HELP DESK personnel grasp the roots of some personnel problems.

Multi User Queue Theory

Many users come to the 400 from a Desk Top reality where they were the only people using some computing resource. Such people can have trouble comprehending

• a multi-user environment in which
• Jobs can go to JOBQ to not run right away, but send Message to MSGQ upon completion;
• Reports to Printer OUTQ wait in line behind other people's reports;
• Reports from multiple people can be accessed.

Compiled Objects

Many users come from a PC environment that makes heavy use of scripted and interpretive languages that read a line of code and execute it. For such individuals, compiled programs can be a foreign concept.

Non-executable files

In much of PC world, concept of programs and data files is alien. Any PC file can be executed ... what it does depends on the 3 letter suffix after the dot at end of name.

In the 400 world, there are files that can be processed, compiled programs that process them, and source code from which the compiled objects were generated.

Members

• Almost everything on 400 is an object.
• All objects are in a Library.
• All 400 Libraries are in a root QSYS Library.
• Files and other objects are in Libraries.
• Files can have more than one Format Layout. All files have at least one format.
• Members are in Files. All files have at least one Member.
• Records are in Members. Each row of a table is another name for a Record.
• Each column of a table is another name for a field of a format layout of a file.

Source

• Files in Libraries
• Software source in File by type of programming language.
• Each member is a different program.
• Each line of the member is a line of code for the program.

Data

• Files in Libraries
• Each File format is different layout of data in that file.
• Each member is different collection of data in that file.

BPCS Examples

• Labor Tickets History ends up in file FLT which has member FLT for the main data and member WORK for input batch that if all goes well will end up in member FLT. WORK uses the same format layout as FLT but the data stays separate until all validation completed on the new input.
• Customer data uses the same format layout for
  • Customer Orders
  • Return of Material from Customers
  • Quotes
  • Input work not yet finished keying
• Each of these scenarios use the same format file layout but the actual data in a different member.