[Libvir] XML-RPC support for libvirt

Fri Mar 10 23:36:30 UTC 2006

T
Thanks Daniel. I agree on both counts: the list I attached (as given to
me) is still pretty anemic, and our Xen CIM consumer today would also
prefer generic, broadly useful common error codes and not just Xen (or
VMWare) specific ones, although some of this normalization will probably be
handled at the CIM level. I'll check out your suggested links. thnx again.

>(and if know of a way to invite the WMWare folks to help here I would be
grateful :-).

I will plant a seed and see if it grows... :-)

- G

Gareth S. Bestor, PhD.
IBM Linux Technology Center
M/S DES2-01
15300 SW Koll Parkway, Beaverton, OR 97006
503-578-3186, T/L 775-3186, Fax 503-578-3186

Daniel Veillard <veillard at redhat.com> on 03/10/2006 03:18:23 PM

Please respond to veillard at redhat.com

To:    Gareth S Bestor/Poughkeepsie/IBM at IBMUS
cc:    libvir-list at redhat.com
Subject:    Re: [Libvir] XML-RPC support for libvirt

On Fri, Mar 10, 2006 at 02:57:57PM -0800, Gareth S Bestor wrote:
> >> Of course, using the xml-rpc code, we now have access to rich fault
> >> information.  Xend never actually returns errors for things and
instead
> >> throws exceptions.
> >
> >  the new error code tries at least to extract the error message when
> >an HTTP POST or GEt fails with an error code, but the XML-RPC should
> >give a far more reliable framework for error handling.
>
> Nice segway... I've been recently pinged a few times by our Xen CIM
> consumers about the lack of good errors coming out of our providers
(which
> in turn are limited by what we get back from libxm today), especially in
> regards to conditions that might cause a create() operation to fail. Do
you
> have a sense today of what errors we might expect to get reported back
from
> libvirt?

  I think the prerequisite read is the following page where I tried to
write down how I planned and implemented error handling:
    http://libvirt.org/errors.html
  it's not coming from nowhere, it's actually the model used by libxml2
"structured" error handling the latest evolution of error processing in
that library. It's not completely broken as people seems to be satisfied
now with it (and its set of users is quite diverse :-)

> Not that this will constitute any sort of meaningful 'requirements' with
> which to write code, but the following is a list of errors that my Xen
CIM
> consumers handle today for the likes VMWare. I am trying to get more info
> on under what specific circumstance(s) these are generated...
>
> ERR_SUCCESS
> ERR_UNABLE_TO_VERIFY_STATE
> ERR_OUT_OF_DISK_SPACE
> ERR_BAD_PARAMETER
> ERR_VM_CONTROL_OP_FAILED
> ERR_INVALID_PARM_NUM
> ERR_CANNOT_ACCESS_DISK_FILE
> ERR_UNKNOWN
> ERR_VIRTUAL_DISK_CREATE_FAILED
> ERR_VM_STUCK
> ERR_CREDENTIALS_NOT_SET
> ERR_UNACCEPTED_CREDENTIALS
> ERR_OUT_OF_MEMORY
> ERR_WRONG_STATE_FOR_OP
> ERR_VM_NOT_FOUND
> ERR_HOST_NOT_FOUND
> ERR_ACCESS_DENIED
> ERR_ALREADY_EXIST
> ERR_OPERATION_FAILED
> ERR_UNDOABLE_DISK_NOT_SUPPORTED
> ERR_VMM_CMD_FORMAT_ERROR
> ERR_COMMUNICATION_NOT_ESTABLISHED
> ERR_FILE_COPY_FAILED
> ERR_NAME_TOO_LONG
> ERR_OS_NOT_SUPPORTED
> ERR_MOUNT_FAILED_DIR_NOT_EMPTY
> ERR_CANT_DISMOUNT_BOOT_OR_SYSTEM
> ERR_FILE_IN_USE

  That look actually a bit short to me for such a complete tool ;-)

> I think error reporting is an area where we will definitely want to drive
> clients' requirements down into the likes of libvirt. Thnx.

  Well you can consult libvirt current list of errors in
    http://libvirt.org/html/libvirt-virterror.html#virErrorNumber
if we can get more details from the Xend internals then the
VIR_ERR_GET_FAILED  and VIR_ERR_POST_FAILED could be replaced by
more precise informations. Also keep in mind that I would like
as much as possible to keep genericity in the API among the different
back-ends (and if know of a way to invite the WMWare folks to help here
I would be grateful :-).

Daniel

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