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From Andrey Stepachev <oct...@gmail.com>
Subject Re: Client-Server wire compatibility?
Date Thu, 05 Mar 2015 17:48:49 GMT
Hi Nick,

> I suppose it's possible the client in the master is never used outside of
localhost, I haven't checked that bit.

Client is definitely used to access meta, which can be hosted anywhere,
so basically we can face with situation when master is upgraded and
hits old region server.

On Thu, Mar 5, 2015 at 5:21 AM, Nick Dimiduk <ndimiduk@gmail.com> wrote:

> My point was that we cannot make this guarantee as there's a client
> embedded in the master (and perhaps other places). We can't enforce the
> order in which components are upgraded, which makes it possible for the new
> client in the new master to reach out to an old RS during the rolling
> upgrade.
>
> I suppose it's possible the client in the master is never used outside of
> localhost, I haven't checked that bit.
>
> On Wednesday, March 4, 2015, lars hofhansl <larsh@apache.org> wrote:
>
> > The idea actually was that a new client can never be 100% supported,
> since
> > a user could use it accessing new features that the server does not
> > understand.The reverse is always possible, since the old client can
> expose
> > anything new unduly we can always upgrade the server as old as it doesn't
> > break the old client.
> > Supporting both ways is too limiting I think, at least for minor version.
> > For example we might want to add a *new* RPC.As long as we only support
> old
> > client with new servers we can do that. In any other combination that
> would
> > not (as easily) possible.
> > That's why I phrased it only that way in my version proposal.
> >
> > For patch releases it's reasonable to support it both ways.The book is
> > currently unavailable from the HBase site, so I can't check the exact
> > wording we ended up with.
> >
> > -- Lars
> >       From: Nick Dimiduk <ndimiduk@gmail.com <javascript:;>>
> >  To: hbase-dev <dev@hbase.apache.org <javascript:;>>
> >  Sent: Wednesday, March 4, 2015 4:49 PM
> >  Subject: Re: Client-Server wire compatibility?
> >
> > I believe your posted example is intended to be supported. There's no
> > enforcement, for instance, that the master is upgraded before all RS's.
> >
> >
> >
> > On Wed, Mar 4, 2015 at 4:06 PM, Matteo Bertozzi <theo.bertozzi@gmail.com
> > <javascript:;>>
> > wrote:
> >
> > > the book (http://hbase.apache.org/book.html#hbase.versioning)
> > > talks about "only allow upgrading the server first" to use new APIs.
> > >
> > > what about a new client talking to an old server for "old" operations?
> > > For example: If I have a 1.1 client, can I ask a 1.0 server to create a
> > > table?
> > >
> >
> >
> >
>



-- 
Andrey.

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