IMACS Software Documentation

Location of this document: http://instrumentation.obs.carnegiescience.edu/Software/IMACS/xdbserver.html

IMACS (X11) Database

The IMACS database utilizes X11 properties of the Xserver root window. The xdbserver maintains a list of key/value pairs that are stored as properties of the X11 root window. The name is prefixed by the string "xdb_" to distinguish the the IMACS database properties from other properties.
Each process (GUI) subscribes with the Xserver (Xorg, Xquartz) to receive updates to all X11 properties of the root window. The process then checks the property name for the prefix "xdb_" before interpreting the property atom as a string. Each string in turn may be converted to a number (integer or double-float).

DataBase - Messages

Data Base Window

The xdbmanager process maintains a list of all key/value pairs (X11 properties) and displays them on its window.

This window may be used to change the property value by double-clicking on the selected line.

Messages Window

A special X11 root property allows (GUI) processes to send message strings to the xdbserver process. The xdbserver in turn displays these messages on its Messages window.

Each message contains a flag (0=normal, 1=warning, 2=error) that is indicated on the messages window as the color of the "LED" to the left of the message time (0=green, 1=yellow, 2=red).

Christoph C. Birk, Carnegie Observatories (last updated: 2016-02-03)