|Title: ||Eloquence TASKID usage explained|
|Author: ||Michael Marxmeier (firstname.lastname@example.org)|
Q: What is a TASKID
Q: What is a primary and secondary task
A TASKID is a unique identifier for each Eloquence process.
This goes back to the dark ages (HP250/HP260) when tasks (the
functional equivalent of a eloqcore process) were created statically
during the boot process and only a few of them existed.
Each TASK was either associated permanently with a terminal device
(in this case it was a primary task) or it could be allocated
and associated temporarily with a terminal device (so it was a
This concept does not make too much sense these days but unfortunately
it was necessary to support it in Eloquence since a lot of
software used to depend on specific TASKID values or required
TASKIDs to be in a specific range.
How does Eloquence make use of TASKID
The pool of available TASKID values is defined in the eloq.config
(for A.05.xx) or eloqsd.cfg (A.06.xx) configuration file.
configuration file /etc/opt/elolquence/eloq.config
NUSERS - maximum number of simultaneous sessions
that can access the shared memory
limits: 1 .. 400
NTASKS - maximum number of available secondary tasks
limits: 0 .. NUSERS - 1
configuration file /etc/opt/eloquence6/eloqsd.cfg
MaxUsers Maximum number of eloqcore processes on the local
system. The default value is 40.
MaxTasks Maximum number of TASKIDs to reserve for "secondary"
eloqcore processes. If you don't know what this is good
for, you probably don't need it :-)
The default value is 20
The NUSERS or MaxUsers configuration value specifies the highest
valid TASKID. The NTASKS or MaxTasks value specifies how much
TASKIDs should be reserverd for secondary TASKS.
<--- MaxUsers / NUSERS ------------------->
<-- MaxTasks/NTASKS -->
| primary | secondary |
| taskid | taskid |
The Eloquence daemon (either eloqd for A.05.xx or eloqsd for
A.06.xx) it makes shure that TASKID values are unique.
For A.06.xx, if the eloqsd server is not running, the taskid
is either set to 1 or the process id (depending on platform).
Unless the taskid is specified on the command line (using the -taskid
commandline option), Eloquence will allocate a taskid when
either eloq or eloqcore is started.
Both eloq and eloqcore will try to allocate a primary taskid.
If not primary taskid is available, eloq fails with the
error message "No taskid available"
On the HP-UX platform, a primary taskid is allocated by making
use of the ttyslot() function, which returns a fixed identifier
for a tty device, depending on the position in /etc/utmp file
(which depends on the poition in the /etc/inittab file for
This was helpful to emulate previous behaviour when mostly
terminals where used to login to the system.
The simple C program below demonstrates how Eloquence on
the HP-UX platform allocates the taskid.
int t = ttyslot() - 5;
if(t < 1}
t = 1;
echo "primary taskid is %d\n", t);
However this aproach does not work well with network based
logins (using pty devices) since the ttyslot() return could
return values which exceed the range of primary TASKIDs.
On the Linux platform, the first avaiable primary TASKID is
If no primary taskid is available, eloqcore will try to
allocate a secondary taskid instead. if no-one is available,
it fails with the message "No secondary task id available"
The first available secondary TASKID is used.
How TASKID is used with Eloquence
The value of the TASKID is returned by the TASKID and USRID functions.
TASKIDs are used with the TASK statements (see below) to implement
foreground/background processes (virtual terminal facilities).
Starting eloq (not eloqcore) enables you to handle secondary
tasks with the following commands:
REQUEST #n request the ownership of a secondary task with
RELEASE #n terminate the ownership of a secondary TASK
with the taskid n
ATTACH #n operation control is passed to the TASK with
DETACH #n operation control is given back to the primary
task that owns the secondary task with taskid n
In order to use secondary tasks, your task must be a primary task.
Suggested use of TASKID in future programs
Simple answer: Don't use it. At most assume TASKID have a unique
value but don't assume a specific value range. Future Eloquence
versions may return the process ID instead of the TASKID
or may remove the distinction of primary and secondary
eloq fails with error message "No taskid available"
Increase the NUSERS / MaxUsers value
or specify the taskid on the command line
eloqcore fails with error message "No secondary task id available"
increase the NTASKS / MaxTasks value. Since this reduces
the available primary tasks, you may also want to increase
the NUSERS / Maxusers.
eloqcore fails with ERROR 400
you need to start eloq instead of eloqcore to make use
of secondary tasks.