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From kishore g <g.kish...@gmail.com>
Subject Re: Helix V2 0.7.0
Date Sat, 22 Feb 2014 18:44:19 GMT
Good suggestion, I think Vinayak had suggestions on similar lines but I
think he suggestion writing high level api's on top of existing api's, as
opposed to changing the  changing the underlying implementation. What that
means is we leave the existing api's as is but add high level api. What
this means is we can keep the core as is but add helix-api module that
provides high level interfaces. We can re-use existing implementation under
the hood. I like the idea of creating a separate module helix-api that is
decoupled from implementation. This will enforce us to have no dependency
on zookeeper in api and allows one to plug other forms of storage. For
example many usecases dont need the level of consistency we get from
Zookeeper.

Looks like we might have to make decisions on a case by case basis.

Can we make a decision of having a helix-api package.

thanks,
Kishore G


On Sat, Feb 22, 2014 at 10:09 AM, Kanak Biscuitwala <kanak.b@hotmail.com>wrote:

> The biggest problem is that we pretty much have to backport bug fixes
> forever if we completely break compatibility. Here's what I think we could
> do:
>
> 1) Remove APIs that we're confident no one uses or can use (the alerting
> stuff)
> 2) Keep the interfaces for the most common currently used APIs
> (HelixManagerFactory, HelixManager, HelixAdmin, ClusterSetup, command line,
> REST), but use our new implementations underneath (HelixConnection,
> HelixController, HelixParticipant, HelixSpectator, HelixAdministrator).
> This means there will be breakages for people who used the implementation
> classes directly, but the changes would be minor.
> 3) Provide adapters between common new and old APIs
> (HelixConnectionAdapter is an example)
> 4) Maintain the model package as-is
>
> This way, there's a clear transition path from one branch to another and
> we can eventually end support for the old branch.
> ________________________________
> > Date: Sat, 22 Feb 2014 07:33:10 -0800
> > Subject: Helix V2 0.7.0
> > From: g.kishore@gmail.com
> > To: dev@helix.apache.org; user@helix.apache.org
> >
> > Hi,
> >
> > We have made lot of good changes in 0.7.0 and improved the api's.
> > However, I think it is not easy/intuitive for a new user. One of the
> > problems with 0.7.0 code is that we tried to maintain complete backward
> > compatibility with respect to both logical api's and physical layout on
> > zookeeper.
> >
> > Trying to maintain the logical api backward compatibility has
> > definitely caused some pain and did not allow us to do the right thing
> > in 0.7.0 and it has made our code base huge. The reasoning here is -
> > when we built Helix ((almost 3 years back), we did not anticipate Helix
> > being used in other systems. So our main focus was minimal code and to
> > make sure it works for the use case we had. We did not gather much
> > feedback from users.
> >
> > However, we are seeing the usage grow and while everyone agrees that
> > the high level concepts are good, it is apparent that api's are making
> > people shy away from Helix. I would even say some of the terminologies
> > are confusing until you spend quite some time with Helix.
> >
> > I want to see what others think about this.
> >
> > We have two options going forward
> >
> > Option1: Continue to maintain backward compatibility and improving the
> api's
> > Option2: Break the api compatibility and call it Helix V2. We redesign
> > our api's and make it more intuitive and easier/flexible to use.
> >
> > I think the core functionality and design is great and don't see much
> > change needed in the architecture (Do let us know if you think we need
> > any change). What is lacking is documentation and a simple set of api's
> > that are intuitive.
> >
> > While Option 1 is great for existing users, I prefer Option2. We will
> > redesign the 0.7.0 api's without maintaining backward compatibility.
> > Lot of work has already been done in 0.7.0, so we are not that far.
> > This also gives chance to the community to contribute and provide
> > suggestions/feedback/ideas.
> >
> > For existing users, we will continue to maintain 0.6.2 and continue to
> > make critical bug fixes. But no new features will be added.
> >
> > Thoughts ?
> >
> > thanks,
> > Kishore G
>

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