Experimental Physics and
Industrial Control System

[email protected] (Jeff Hill) · Mon, 26 Jun 95 11:21:29 MDT

> 1) startCArepeater does nothing.  This is where I am confused.
>    startCArepeater just calls ca_task_initialize which returns
>    without doing anything if ca_static is NULL.

The subroutine ca_task_initialize() returns without doing anything
if ca_static _isnt_ NULL.

>    I can't seem to
>    find where it is initialized since it is defined as
>    a pointer.

The CA private pointer ca_static is in the CA client library. It is
initialized to NULL.

> startCArepeater also doesn't give any error messages.
>
> 2) Given the above, the clients don't seem to start caRepeater; however,
>    if I start it by hand (e.g.    caRepeater &    ), then ca_test
>    can talk to my crate.
>

Clients should initially connect independent of whether the CA repeater
is running or not. However, clients will not properly reconnect
unless the repeater is running.

Note that there are several ways to a get a ca repeater process running:
1) Type "caRepeater &"
2) Type "startCArepeater"
3) Run any CA client.

For normal operation, all of the options above require that a directory
containing the image "caRepeater" is in your path.

Options two and three above start the CA repeater using the execlp()
system call. If this fails (because the repeater executable cant be
found in the path) they will start the repeater with a fork() call.
If this occurs a long message is printed indicating that the repeater
will inherit parents the process name and resources.

Note also that when porting to new OS (such as solaris) we initially ran into
problems related to the test used to determine if the CA repeater
is already running. Under options 2 & 3 above the client - in
ca_task_initialize() - attempts to attach to the repeater's port.
If this is successful the port is released and the repeater is
spawned. However, under updated IP kernels that have multicast
there are some subtleties related to the order of socket options
which must be adhered to or this test fails to work correctly.
The version of the code you are working with is properly updated to
take these subtleties into account. Nevertheless, I am mentioning
this problem in passing since you are porting to a new version of UNIX.

If the repeater is properly spawned with execlp() you should be
able to determine if it is running by looking for a process
with the name "caRepeater".

Jeff

______________________________________________________________________
Jeffrey O. Hill                 Internet        [email protected]
LANL MS H820                    Voice           505 665 1831
Los Alamos, NM 87545 USA        FAX             505 665 5107

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System