Note: The code accompanying this article is available for download here.

Last week, I wrote about linked lists. Each node in the list points to another node. Binary trees differ from linked lists in only one way–each node has two pointers to other nodes. How you label these pointers is up to you, but most people choose to call them left and right.

Here’s a data structure that defines a node with left and right pointers.

     D Record          ds                  qualified
     D   Name                        20a
     D   City                        12a
     D   Left                          *
     D   Right                         *

A node that points to one

We have a database file to which records are added throughout the day. The key is a five-digit packed decimal whole number, and the program that writes to the file increments this number when adding a new record to the file. During the day, another program processes and deletes records throughout the file, leaving gaps between sequence numbers. At the end of each day, we would like to renumber the remaining records, beginning again at sequence number one, to remove the gaps and be prepared for a fresh start the next day. Can we use an SQL UPDATE statement to

Last week, I began outlining a basic plan for monitoring and answering i/OS error messages, allowing you to resolve system and programming issues without having dedicated 24x7x365 personnel on site. That article focused on detection and notification of errors. This week, I’ll focus on extending the plan to include allowing responders to correct issues from anywhere, to automatically answer error messages without human input, and some other things to do after the error message is resolved.

The Basic Structure of i/OS Error Monitoring and Response

As outlined in Part 1, an i/OS error monitoring and response system contains