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From Stephen Connolly <stephen.alan.conno...@gmail.com>
Subject Re: Reoganizing drivers
Date Wed, 13 Jul 2011 08:10:59 GMT
On 13 July 2011 00:47, Jonathan Ellis <jbellis@gmail.com> wrote:
> On Sat, Jul 9, 2011 at 8:29 PM, Rick Shaw <wfshaw@gmail.com> wrote:
>>
>> On Jul 7, 2011, at 10:53 AM, Eric Evans wrote:
>>
>>> On Wed, 2011-07-06 at 13:33 -0500, Jonathan Ellis wrote:
>>>> - the git mirror won't pick up anything under drivers/
>>>
>>> Has there been any effort made to have INFRA add it?
>
> Aaron asked, they said they only do standard svn trunk + branches + tags.

But I think what they mean is that you'd need to tweak things a little, e.g.

svn mkdir http://svn.apache.org/repos/asf/cassandra/server

svn mv http://svn.apache.org/repos/asf/cassandra/trunk
http://svn.apache.org/repos/asf/cassandra/tags
http://svn.apache.org/repos/asf/cassandra/branches
http://svn.apache.org/repos/asf/cassandra/server/

svn mkdir http://svn.apache.org/repos/asf/cassandra/drivers/trunk

svn mv http://svn.apache.org/repos/asf/cassandra/drivers/java
http://svn.apache.org/repos/asf/cassandra/drivers/py
http://svn.apache.org/repos/asf/cassandra/drivers/trunk/

and basically end up with at the
http://svn.apache.org/repos/asf/cassandra/ a set of directories with
trunk/tags/branches underneath.

In fact I suspect you would not even have to move the main branches
(which would be better for svn mergeinfo) as they should be able to
retain the git repo for that as is and just by structuring the drivers
directory with a trunk/tags/branches (and sure keep branches empty if
you want) they could give you
git://git.apache.org/cassandra-drivers.git for the drivers and
git://git.apache.org/cassandra.git remains in place and as is for the
core/server

if they give you any hassle just point out that they do this already
for mina, myfaces, maven, etc... and if it is a big issue you can
always rename cassandra to massandra as they seem to do it for any
project beinging with "m" ;-)

>
>>> What do you mean by "but not have multiple versions for 0.8 branch"?
>
> I mean it would live in trunk but only in trunk -- there would be no
> branches/0.8/drivers or branches/1.0/drivers.
>
>> Can't we keep the /drivers code in the trunk and just have separate Ant tasks for
building the driver parts independent of the tasks for for the server?
>
> Right, this feels ideal to me.  Otherwise the "right" way to handle it
> is to download a Cassandra stuff-the-driver-needs jar from the maven
> repo.

I will be providing a patch that will allow deploying -SNAPSHOTs to
the apache snapshot repository once I get some releases off the decks
at Maven, that will make life easier for the Hector guys etc (as they
can follow trunk more easily, and push -SNAPSHOTs themselves to allow
for easier user testing) but a side-effect is that it would make life
easier if you went with this approach... and remember that the maven
repo in this case does not even need to go off your machine as you can
just install the core deps in your local repo by doing a build of core
locally.

> I'd rather just have {cassandra} and {driver} build targets
> personally, from the same tree, rather than introducing this
> intermediate dependency.

It does bring up versioning... the tag for drivers releases will
include cassandra stuff too... I have the feeling that you cannot have
your cake and eat it too
>
>> Another thought would be to keep it in the separate tree as it is now, and dumb down
the driver build to just build the JAR artifacts (binary, source, and javadoc). and do all
testing and integration work in the server-side trunk by using just the Driver jar as a dependency
for the tests in the server tree?
>
> Then you have the reverse problem, that running the test suite
> requires this other checkout to be around somewhere.

But the driver jar is supposed to be more stable, and have a much
slower release cadence. I see much less of an issue pulling the driver
jar from the (local/remote) maven repo than pulling the core stuff.

I would see this option as being closer to the way you guys seem to
want to work...

But I will raise this one question....

The tension seems to be between whether to re-release a drivers jar
with every core release, or have it with its own release cadence. To
my mind, from the Maven Pom point-of-view as long as the drivers
depend on core classes (and that includes thrift) it needs to at least
match the release cadence of core releases (i.e. you would need one
release for each release of core, and if it needs its own bug-fixes
they would be extra releases)

The major pain for releasing the drivers jar is that you have to test
it... building it is no big shakes but testing is where the effort
lies. Now the testing effort has to happen anyway at the main core
release cadence, because even if you think you don't need to rebuild
drivers for the core 0.8.2 release, you do need to test that the
drivers jar you tested against 0.8.1 still works [or at least do some
investigation to say that the changes cannot affect it working...
chaos butterflies will still want testing though*] and that is
ignoring the Maven Pom issue§

So here is the question: Does it really make sense to release the
driver jar independently? Yes you save on building that one jar, but
that is just a 2-3s increase in build time, and you cannot save on
your testing effort... the only thing that it might buy is a saving on
building effort for users of cassandra**

* and your testing should be automated and run every time so a manual
impact assessment will always be more work than just running the tests

§ which I am trying to keep out of this, as you guys seem to ignore
what I say when ever Maven comes up ;-)

** in that if they are willing to trust the Cassandra testing effort,
they could just upgrade the server and not upgrade their application
to include the matching driver.jar... but what company, that cares
about testing, is going to be happy with that story... none that I
know... upgrading the DB server... well you will want to retest your
application against the new one won't you... and testing effort should
always be greater than building effort (or else you either have no
tests or a crappy build) so it would be no skin off your nose
including an updated drivers jar.

>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of DataStax, the source for professional Cassandra support
> http://www.datastax.com
>

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