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From dlmar...@comcast.net
Subject Re: [VOTE] ACCUMULO-3176
Date Tue, 02 Dec 2014 19:07:45 GMT

The impetus for these changes comes from the discussion in ACCUMULO-118. This API change and
the issues surrounding the per-table Volume Chooser is a follow-on feature to Multi-Volume
support that was added in 1.5. I want/need these changes. 

In ACCUMULO-2844 you wanted, if not demanded, to make a breaking API change (changing the
name of the Master) in the development and all bug fix branches without discussion. Here we
have a non-breaking API change in a major release and all of a sudden it's an issue. By that
logic, we should scrub 1.7 for all API changes and revert them. 

At this point I would much rather have these changes committed in 2.0 just so we can stop
having this ridiculous discussion. I'm happy to fork Accumulo and backport these fixes to
the version I need. 

----- Original Message -----

From: "Sean Busbey" <busbey@cloudera.com> 
To: "dev@accumulo apache. org" <dev@accumulo.apache.org> 
Sent: Tuesday, December 2, 2014 1:14:50 PM 
Subject: Re: [VOTE] ACCUMULO-3176 

Responses below. I feel like most of these questions (with the noted 
exception of details on my issue with one of the late compromise positions) 
were previously answered, but I've tried to add additional detail below 
where I may have been unclear in prior exchanges. 

While I agree that objections are the start of a conversation, votes are 
meant to be provide closure so the community can move on to other work. I'd 
ask that we try to bring this thread to a close. 


On Mon, Dec 1, 2014 at 2:40 PM, Keith Turner <keith@deenlo.com> wrote: 

> 
> 
> The question I was most curious about was why you are ok w/ making this API 
> change in 2.0 but not 1.7.0. I do not understand the reasoning behind 
> this. 
> 

As a matter of background, over time I have become more convinced of the 
need for a stable, coherent API. Too many of the end users I have seen 
endure substantial work because of our altering of the API. This applies 
equally for forwards and backwards compatibility. When someone has a 
requirement to use our software and they find that the particular version 
they need to integrate with is different than they initially expected, I 
would like them to not have to endure project delays merely for updating 
use of our API. 

For 2.0, we already have broad consensus around improving our API in 
ACCUMULO-2589 despite the cost it puts on our user base; both because of a 
better delineation of what is and is not expected to stay constant and 
because we'll have a better formulation of a lifecycle for Accumulo related 
resources. In that particular matter, it's the proper lifecycle that I 
personally find compelling enough to broadly cause a burden. This is 
probably colored by my having dealt with ACCUMULO-2128 and its ilk. 

So, given that we're going to be asking our users to deal with a headache 
come 2.0 (which will hopefully be in the next 6-9 months) I would prefer to 
minimize asking them to take on dealing with changes in versions prior to 
that. There may be some future issue that fixes something severe enough to 
warrant changing my position on the matter. This issue did not. 

I talked previously about my position on API changes in general in the 
background info for Josh’s message: 

http://s.apache.org/HJg 

and I had meant to cover the "we already agreed to break things in 2.0" 
side in this admittedly short offer of compromise: 

http://s.apache.org/imf 



On Mon, Dec 1, 2014 at 4:25 PM, Christopher <ctubbsii@apache.org> wrote: 

> Explicit questions and outstanding requests for clarification since your 
> last response (see previous emails for details and context): 
> -> So, are you arguing for no more API additions until 2.0? 
> 

My general preference, as mentioned above and previously in the background 
info Josh asked for, is to avoid API changes prior to 2.0. I am not arguing 
that this stance be taken on as a matter of course through this particular 
vote. 

I think any change to our API, prior to 2.0 or after, should be carefully 
considered. How we plan for users to interact with our software over time 
matters. Through removals we will be directly impacting the ability of 
operational users to adopt our newer versions. Through additions we will be 
impacting how system integrators go about building applications above us. 
It does neither us nor them any good for our API to change merely because 
it improves our abstractions or condenses our support footprint. 

In the consideration of the above and the nice-to-have fixes this 
particular patch brings, I think it can wait for the API overhaul in 2.0. 

The same two previous mailings I mentioned above to Keith are where I went 
through this previously. 



> -> Please address the fact that there is no breakage here... 

-> Another reasonable compromise has also been proposed that seems to 

address all of your concerns. Please explain why it does not. 


I think these are the same question, presuming your "other compromise" is 
the one of adding the new API and leaving the extant create methods 
undeprecated. If not, please let me know what other compromise I missed so 
that I can respond accordingly. 

I covered the breakage part of this explicitly in my response to Keith's 
question about which part of the API move I was concerned with: 

http://s.apache.org/nn5 

Essentially, moving our table creation API to use a configuration object 
instead of the myriad of different arguments is a shift in how we expect 
users to interact with Accumulo. Even if the breakage doesn't happen right 
now, this change is setting downstream users up for pain when the break 
happens. To that same end, users attempting to proactively stay up to date 
on our API will break if they have to move backwards. Yes, this a normal 
part of API evolution. Yes, users will have to do this at some point. I'm 
merely stating that we have already reached consensus on that point being 
2.0 and we should reserve using up the good will of our end users. 

Similarly, simply expanding our API to have multiple long term ways of 
doing table creation isn't tenable. For one, downstream users will ask 
which method to use. Deprecation is how we normally offer them clear 
guidance on where the API is going in the future. Without that, we'll just 
be using some proxy for deprecation (either a javadoc or emails on user@). 
Additionally, since the version that takes a single configuration object is 
clearly the most sustainable approach, the other methods are likely to be 
deprecated and then removed should we end up with additional major versions 
prior to 2.0. 

I covered some of this concern in my response to Brian in the first part of 
my last response: 

http://s.apache.org/0um 



> -> Please explain how you see omitting this API addition is compatible with 
> [the goal of supporting non-major intermediate releases]. Please also 
> explain why, if you consider 1.7 to be a major (expected) release, why such 
> an addition would not be appropriate, but would be appropriate for a future 
> major release (2.0). 


I believe I covered this through a combination of the above explanations to 
Keith and my response to Brian in the first part of my last response: 

http://s.apache.org/0um 

That we are having a 1.7 release at all is a matter of scheduling. There 
are already too many things different in that development line for us to 
release it as a follow on to 1.6 but not enough of our goals for 2.0 are 
done to get that release out. That doesn't mean we should feel free to pack 
as many breaking changes as we want into the release. 



> 
> Brian also asked: 
> -> I don’t see what breakage users would be required to deal with if the 
> proposed changes were made. A new method would be added to the API and some 
> existing methods deprecated (presumably to be removed in 2.0). So how would 
> this hurt our users? 
> 


I think this is covered above. In summary, when we alter our API we need to 
consider long term impact rather than just the immediate release. We are 
already going to ask our users to handle major changes in a relatively 
short time period. 



> -> Given that you are ok with with the change in 2.0, it seems that your 
> objection is not to the content of the change but rather the timing of it. 
> Given that users aren’t required to use the new API method added by the 
> change, this objection and the veto seem invalid to me. Am I missing 
> something? 
> 


I believe the rest of this message restates in detail my concerns about our 
API evolution and specifically why I am on board with the planned breakage 
in the 2.0 release. Let me know where there are particular gaps so I can 
help clarify. 

Please everyone stop this divisive tactic of continuing to claim my veto is 
invalid. The surface of our API and our impact on downstream users are 
valid technical considerations. Our bylaws clearly state what is needed for 
a veto to be sustained and I have already passed that bar. Let’s focus our 
discussion on the underlying problem rather than technicalities of our 
governance. 

-- 
Sean 


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