On 03/18/2013 01:11 PM, Shireesh Anjal wrote:
On 03/18/2013 12:59 PM, Mike Kolesnik wrote:
----- Original Message -----
Hi all,
The current mechanism in oVirt to check whether a feature is
supported
in a particular compatibility version is to use the FeatureSupported
class. e.g.
FeatureSupported.networkLinking(getVm().getVdsGroupCompatibilityVersion())
Checks whether the "network linking" feature is supported for the the
VM's cluster compatibility version. This internally checks whether
the
value of the corresponding config (NetworkLinkingSupported) for the
given compatibility version is true/false.
I'm not sure if this is a good idea, since a feature is typically
supported "from" a particular version. E.g. Gluster support was
introduced in 3.1, and it continues to be available in all subsequent
versions. So I see no point in adding configuration for every version
indicating whether the feature is supported in that version or not. I
suggest to use either of the following options:
You can "merge" the configs into a single config when older versions
go out of the supported versions for the system.
i.e. in 4.0 you can have upgrade script that merges all
GlusterFeatureSupported to one entry instead of several.
Why are we even storing this information in config? Is this something
that can be "configured" at customer site?
1) Instead of using a boolean config for each version, use a single
string config that indicates the "supported from" version e.g.
GlusterSupportedFrom = 3.1. There could be rare cases where a
feature,
for some reason, is removed in some release. In such cases, we could
use
one additional config for the "supported to" version.
2) Continue with the boolean approach, but do not have entries for
every
version; rather make use of the "default value" for majority of
cases,
and add the explicit version mapping for the minority e.g.
GlusterSupported = true by default, and false in case of 3.0 (only
one
config required for 3.0)
I'm not sure why we would want to complicate this simple mechanism?
Is there much to gain?
I think option 1 suggested above is simpler - to implement as well as
to understand.
Let me give you an example of why I don't like current mechanism. I
introduce a version check for a feature that was introduced in 3.1.
I'm being asked now to add three entries in config
3.0 - false
3.1 - true
3.2 - true
It will also mean that when 3.3 goes out, someone has to make sure
that another entry is added for 3.3-true. I think it is not logical as
well as scalable if you have more versions. And it sounds far more
complex (to maintain) than just having
<Feature>SupportedFrom = 3.1
So I would like to know if there are any objections to my proposal. I
intend to use this for at least the gluster related features.
Thoughts?
Regards,
Shireesh
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