[Engine-devel] Jar versions in ovirt-engine

[Juan Hernandez]

On 04/19/2012 04:10 PM, Doron Fediuck wrote:
> On 19/04/12 16:53, Juan Hernandez wrote:
>> On 04/19/2012 03:22 PM, Doron Fediuck wrote:
>>> On 19/04/12 13:26, Juan Hernandez wrote:
>>>> On 04/19/2012 12:00 PM, Doron Fediuck wrote:
>>>>> On 18/04/12 14:04, Juan Hernandez wrote:
>>>>>> On 04/18/2012 09:51 AM, Ofer Schreiber wrote:
>>>>>>> Ever wondered why the version of oVirt's first release is 3.0.0_0001?
>>>>>>> The answer is simple - We use ovirt-engine jar's version as our "main" release version.
>>>>>>>
>>>>>>> Personally, I think the current versioning scheme is ugly. Actually, I can't name even one open-source project using "_" in it's version.
>>>>>>>
>>>>>>> What can we do about it? We have couple of options:
>>>>>>> 1. Leave the engine alone, and use a separate versioning scheme (e.g - use just 3.1.0 as the main version for next release)
>>>>>>> 2. Remove "_" from engine jars
>>>>>>> 3. Do nothing.
>>>>>>>
>>>>>>> I'd like to hear your thoughts, as well as the reasons to use such an unusual versioning scheme.
>>>>>>>
>>>>>>> ---
>>>>>>> Ofer Schreiber
>>>>>>> oVirt Release Manager
>>>>>>> _______________________________________________
>>>>>>> Arch mailing list
>>>>>>> Arch at ovirt.org
>>>>>>> http://lists.ovirt.org/mailman/listinfo/arch
>>>>>>
>>>>>> From my point of view using the 0001 suffix in the names of the jar
>>>>>> files is not a big problem, but I agree that using it in the release
>>>>>> number is ugly, and it produces issues/discussions during packaging. I
>>>>>> vote for option #1: use 3.1.0 for the next main version.
>>>>>>
>>>>>
>>>>> The original versioning scheme was due to a bug in maven2.
>>>>>
>>>>> Juan, I've read some of the Java packaging concepts, but didn't see
>>>>> (or missed) thoughts about modular versioning (ie- artifacts).
>>>>>
>>>>> Here are the things to consider here;
>>>>>
>>>>> - Current RPM's are using the version declared in the POM files.
>>>>> Should this concept remain?
>>>>> * I think it should remain, as other packaging systems should
>>>>> be able to use it as well and end-up is the similar project version.
>>>>
>>>> I can talk from the Fedora point of view only, as that is what I know a bit.
>>>>
>>>> In Fedora there can be only one version of a given jar file installed in
>>>> the system, so there is no point in adding a version number to the name
>>>> of that jar file: the version number is already in the package
>>>> containing that jar file. In fact if the build generates jar files with
>>>> version numbers in the name the RPM should remove those jar files. That
>>>> is why I say that having any kind of numbers in the names of the jars is
>>>> not important: we have to remove them anyway.
>>>>
>>>> Packaging guidelines (see [1]) recommend to avoid version numbers in the
>>>> jar files, and I think that makes sense.
>>>>
>>> This would be the easy solution.
>>
>> Again talking only about Fedora:
>>
>> Having just one version of every jar is not simple at all, in fact it
>> requires a lot of work to make sure that the selected versions work
>> properly together.
>>
> See below, we actually share the same view...
> 
>>> What happens when you have more than a single Java app, and both
>>> using different versions of the same jar file? This means that one
>>> of the app's will need to bring it along and use it locally, rather
>>> than system-level usage.
>>
>> What happens is that both applications have to be patched so that they
>> work correctly with the same version of that jar file. If possible the
>> patches are pushed upstream, if not they applied as part of the package.
>> Embedding another version of that jar file in one of the applications is
>> not allowed, in fact that is something that packagers have to undo quite
>> often.
>>
> See below... converging into the latest jar is what I figured that
> will happen. Still, as I see it such constraints are not really needed.
>>> I'm guessing if we assume such a constraint the solution will be
>>> to force all app's to use latest jar version, which isn't trivial.
>>
>> I agree completely, it is not trivial at all, that is where packagers
>> expend most of their time.
>>
>>> So some distro's will allow of concept of slotted installation.
>>> This means I currently /have/ 2 working versions of postgres in
>>> my laptop (using Gentoo)-
>>>
>>> equery l postgresql-server
>>>  * Searching for postgresql-server ...
>>> [IP-] [  ] dev-db/postgresql-server-8.4.11:8.4
>>> [IP-] [  ] dev-db/postgresql-server-9.1.3:9.1
>>>
>>> The same works on my laptop for Maven, Java, Python and many others.
>>> If you think about it, Fedora supports slotted installation for
>>> kernels, and then added alternatives to do that with other packages
>>> as well (mta, Java..). So there's a need and a way to handle several
>>> versions of the same library (regardless of the language), and
>>> we should be careful when taking such assumptions. At least try
>>> to be as flexible as possible, to allow others to join in.
>>
>> In Fedora that is allowed only for major versions: java-1.7.0 and
>> java-1.6.0, maven 2 and maven 3, so on, but not usually for minor
>> versions (there are exceptions).
>>
> It's a good start.
> 
>>> So learning from Fedora I'd say- let the RPM install in a versioned
>>> folder (ie- /usr/lib/jvm/jre-1.5.0-gcj/..), and leave the jar
>>> files without versions for now. In the future we may need to change it
>>> as some disrto's may use sym links to indicate the latest jar.
>>> In such a case the RPM will stripdown the version from the artifact.
>>
>> What we are currently doing with the Fedora ovirt-engine package is that
>> jar files are installed to /usr/share/java/ovirt-engine, with names like
>> bll.jar, common.jar, compat.jar, etc. The RPM takes care of stripping
>> the version numbers generated by the upstream build. This doesn't
>> preclude other distros from doing it in a different way, using version
>> numbers or symlinks.
>>
> Why not /usr/share/java/ovirt-engine-3/ ? I do not see someone using
> engine3 and engine4 on the same machine, but he may need to have
> engine-config v3 to handle previous instance and engine-config v4
> to handle current instance, so we could have a good infra if we
> keep the major version.

The only thing I have against ovirt-engine-3 is that the packaging
guidelines recommend to use /usr/share/java/%{name}, where %{name} is
the name of the package, and the package has already been approved with
the name ovirt-engine. Next major version (not 3.1, that is a minor
version) can perfectly be named ovirt-engine4 or ovirt4-engine.