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Problems in XML CIB

 

 

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Ulrich.Windl at rz

Nov 17, 2011, 12:09 AM

Post #1 of 3 (1327 views)
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Problems in XML CIB

Hello,

I tried to understand the structure of the XML CIB a little bit better, and I found at least two major problems:

1) the "nvpair" element is missing a "datatype": As a consequence, generic interpretation or checking of nvpair out of context is difficult. Instead the application must know what the individual types of the variables are (e.g. "cluster-recheck-interval").

2) The "id"s are not free of semantic: An ID only needs one property: "Two IDs are equal iff their objects are the same". In contrast, IDs are rich of semantics in the CIB, e.g. id="cib-bootstrap-options-cluster-infrastructure". Also, "id-like" attributes are longer than needed (e.g. "transition-key", "transition-magic", "op-digest"): I see little sense adding extra information to a universally unique ID, despite of the fact that I don't see why a "local" cluster resource needs a universally unique ID at all.A better approach would be to use just some sequence number when assigning a new id. Wherever this will break using the XML CIB, the XML structure should be fixed instead. As a contrast, the "dc-uuid" attribute just uses the local hostname (without domain), which most likely is not (as the name might suggest) universally unique.

3) Data types are used inconsistently: In "op" elements, the "interval" attribute is in "free form" time specification, like "30s", while the interval elsewhere (e.g. "lrm_rsc_op") is in milliseconds. Timestamps in "lrm_rsc_op" usually use "ctime" values, but attribute "cib-last-written" is using an ASCII string.

Regards,
Ulrich


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lmb at suse

Nov 17, 2011, 1:18 AM

Post #2 of 3 (1235 views)
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Re: Problems in XML CIB [In reply to]

On 2011-11-17T09:09:29, Ulrich Windl <Ulrich.Windl [at] rz> wrote:

> Hello,
>
> I tried to understand the structure of the XML CIB a little bit better, and I found at least two major problems:

That's something to discuss on the pacemaker mailing list.

"Major problems" is, of course, subject to interpretation. But patches
are welcome.


Regards,
Lars

--
Architect Storage/HA
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 21284 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde

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andrew at beekhof

Nov 17, 2011, 3:12 PM

Post #3 of 3 (1225 views)
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Re: [Linux-HA] Problems in XML CIB [In reply to]

On Thu, Nov 17, 2011 at 8:18 PM, Lars Marowsky-Bree <lmb [at] suse> wrote:
> On 2011-11-17T09:09:29, Ulrich Windl <Ulrich.Windl [at] rz> wrote:
>
>> Hello,
>>
>> I tried to understand the structure of the XML CIB a little bit better, and I found at least two major problems:
>
> That's something to discuss on the pacemaker mailing list.
>
> "Major problems" is, of course, subject to interpretation. But patches
> are welcome.

Actually, in these three cases, not really.

>
>
> Regards,
>    Lars
>
> --
> Architect Storage/HA
> SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 21284 (AG Nürnberg)
> "Experience is the name everyone gives to their mistakes." -- Oscar Wilde
>
> _______________________________________________
> Linux-HA mailing list
> Linux-HA [at] lists
> http://lists.linux-ha.org/mailman/listinfo/linux-ha
> See also: http://linux-ha.org/ReportingProblems
>
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