This document describes the interface between ksysguard and
ksysguardd. ksysguardd is started as a child of ksysguard, either
directly or via a shell. 

This client/server design was chosen, because on some operating
systems the back-end needs elevated permissions. Since C++ programs
should NEVER have setgid/setuid permissions, a plain C back-end was
needed. It also allowed for an easy network support using existing
security mechanisms (ssh).

The communication runs over stdin, stdout and stderr. ksysguard sends
commands and ksysguardd answers to them. Each answer ends with the
string "\nksysguardd> ". The set of commands that each ksysguardd
implementation supports can be very different. There are only a very
few mandatory command and a few recommended commands.

The mandatory commands are 'monitors', 'test' and 'quit'.
The recommended commands are:

cpu/idle        integer
cpu/sys integer
cpu/nice        integer
cpu/user        integer
mem/swap/free   integer
mem/swap/used   integer
mem/physical/cached     integer
mem/physical/buf        integer
mem/physical/application        integer
mem/physical/used       integer
mem/physical/free       integer
ps      table
pscount	integer

Without these commands KSysGuard is not very helpful.

The 'monitors' command returns the list of available sensors. The
output looks like this:

--------
mem/physical/free       integer
ps      table
pscount integer
ksysguardd> 
--------

Sensor names can be hierarchical. Each level is separated by a
/. ksysguard uses a tree widget in the SensorBrowser to display the
commands in a tree. Every sensor name must be followed by the type of
the sensor separated by a tab. Currently 3 different types of sensors
are supported, integer, float and table. The table sensor returns the
information for the ProcessController widget. To find out more about a
sensor an additional command must be implemented for each sensor that
has a questionmark appended to the sensor name. It can be used to
find out more about the sensor.

--------
ksysguardd> mem/physical/free?
Free Memory     0       260708  KB
ksysguardd>
--------

integer and float sensor return a short description, the minimum and
maximum value and the unit. All fields are again separated by
tabs. The minimum and maximum values can both be 0 to trigger the
auto-range feature of the display.

--------
ksysguardd> ps?
Name    PID     PPID    UID     GID     Status  User%   System% Nice    VmSize VmRss    VmLib   Login   Command
s       d       d       d       d       S       f       f       d       d      sksysguardd>
--------

This is the output of the ps? inquiry command. The ps command is the
only recommended command. The answer to ps? consists of 2 lines. Both
lines have the same number of fields each separated by a tab. The
first line specifies the name of the columns and the second the type
of the values in the column.

d: integer value
f: floating point value
s: string value
S: string value that needs to be translated
   Strings must be added to the ProcessList::columnDict dictionary.

For the ProcessController to function properly the Name and PID
columns are mandatory. All other columns are optional and their
content may be implementation dependant. It is highly recommended not
to deviate from the Linux implementation unless absolutely
unavoidable, in order to provide a consistent interface across all
platforms.

The 'test' command can be used by the front-end to find out if a
certain other command is supported by this version of ksysguardd. The
command returns "1\n" if the command is supported and "0\n" if the
command is not supported.

The 'quit' command terminates ksysguardd.

ksysguardd may support dynamic monitor sets. If a CPU is added or an
interface disabled, monitors may be added or removed. To notify the
front-end about this, you need to send the string "RECONFIGURE\n" over
stderr. This causes the front-end to request the list of monitors
again and adapt it's layout accordingly. If ksysguardd receives a
command it doesn't know it has to reply with "UNKNOWN
COMMAND\nksysguardd> ".

ksysguardd does not handle native language support. In order to have a
minimum installation (only a single file) on the monitored machine,
all translation are handled by the front-end. Please see the files
gui/SensorManger.cc and gui/ProcessTable.cc if you add new strings.

Chris <cs@kde.org>
