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From Vladimir Rodionov <vladrodio...@gmail.com>
Subject Re: On coprocessor API evolution
Date Fri, 16 May 2014 17:59:59 GMT
1) Have default implementations (abstract classes) for every interface from
Coprocessor API.
2) Advise coprocessor users not to implement interface directly but sub
class default impl.
3) Preserve backward compatibility by adding only new hooks/methods
4) DO NOT CHANGE existing API (no method renaming, method parameter type
changes etc)
5) Have a regression tests to check backward compatibility.

-Vladimir



On Fri, May 16, 2014 at 9:13 AM, Michael Segel <michael_segel@hotmail.com>wrote:

> Until you move the coprocessor out of the RS space and into its own
> sandbox… saying security and coprocessor in the same sentence is a joke.
> Oh wait… you were serious… :-(
>
> I’d say there’s a significant rethink on coprocessors that’s required.
>
> Anyone running a secure (kerberos) cluster, will want to allow system
> coprocessors but then write a coprocessor that reject user coprocessors.
>
> Just putting it out there…
>
> On May 15, 2014, at 2:13 AM, Andrew Purtell <apurtell@apache.org> wrote:
>
> > Because coprocessor APIs are so tightly bound with internals, if we apply
> > suggested rules like as mentioned on HBASE-11054:
> >
> >      I'd say policy should be no changes to method apis across minor
> > versions
> >
> > This will lock coprocessor based components to the limitations of the API
> > as we encounter them. Core code does not suffer this limitation, we are
> > otherwise free to refactor and change internal methods. For example, if
> we
> > apply this policy to the 0.98 branch, then we will have to abandon
> further
> > security feature development there and move to trunk only. This is
> because
> > we already are aware that coprocessor APIs as they stand are insufficient
> > still.
> >
> > Coprocessor APIs are a special class of internal method. We have had a
> > tension between allowing freedom of movement for developing them out and
> > providing some measure of stability for implementors for a while.
> >
> > It is my belief that the way forward is something like HBASE-11125.
> Perhaps
> > we can take this discussion to that JIRA and have this long overdue
> > conversation.
> >
> > Regarding security features specifically, I would also like to call your
> > attention to HBASE-11127. I think security has been an optional feature
> > long enough, it is becoming a core requirement for the project, so should
> > be moved into core. Sure, we can therefore sidestep any issues with
> > coprocessor API sufficiency for hosting security features. However, in my
> > opinion we should pursue both HBASE-11125 and HBASE-11127; the first to
> > provide the relative stability long asked for by coprocessor API users,
> the
> > latter to cleanly solve emerging issues with concurrency and versioning.
> >
> >
> > --
> > Best regards,
> >
> >   - Andy
> >
> > Problems worthy of attack prove their worth by hitting back. - Piet Hein
> > (via Tom White)
>
>

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