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HBase, mail # dev - Declaring HBase Public API in 0.94


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Aleksandr Shulman 2013-04-08, 18:07
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Elliott Clark 2013-04-08, 20:49
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Ted Yu 2013-04-08, 21:24
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Todd Lipcon 2013-04-08, 21:50
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Enis Söztutar 2013-04-08, 22:07
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Re: Declaring HBase Public API in 0.94
lars hofhansl 2013-04-08, 22:08
It seems we could just generally document that:
- no RPC incompatibilities
- no API breaking changes to any user facing classes (now we'll pay better attention to this)
- best effort to keep coprocessor API changes backward compatible

If - on the other hand - we wanted to automate API checks then we'd need tagging (either in form of an annotation or Javadoc)

+1 on the javadoc tagging if you're willing to take than on. As other have said -1 on pulling Interface Audience in.
Your set of classes looks good.

-- Lars

________________________________
 From: Elliott Clark <[EMAIL PROTECTED]>
To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
Sent: Monday, April 8, 2013 1:49 PM
Subject: Re: Declaring HBase Public API in 0.94
 
Please don't pull in @InterfaceAudience.  Keeping 0.2x compatibility was
something that was hard won in 0.94, it would be a real shame to loose that
now.
On Mon, Apr 8, 2013 at 11:07 AM, Aleksandr Shulman <[EMAIL PROTECTED]>wrote:

> Hi everyone,
>
> In light of all the conversation on compatibility, I wanted to float the
> idea of documenting which Java packages, classes, and methods we want to
> declare as being API compatible in 0.94.x. I'd like your input on:
> 1. JavaDoc vs. using AudienceInterface
> 2. What the javadoc notation should look like
> 3. Which pieces of code should be tagged
>
> What do I mean by documenting API compatibility? That means that we suggest
> the anyone building applications use specific methods because they would
> continue to be both binary and RPC-compatible going forward. Any
> application written, either running on a node of a cluster or on a remote
> machine, would continue to work properly without recompile for all versions
> of 0.94.x running on the cluster.
>
> *Benefits:*
> It would prevent developers from using calls that are subject to change.
> This would give developers more confidence in using the platform, which
> will encourage more development on our platform.
> 0.94 will still be with us for some time and I think the
> better-late-than-never approach will save us pain down the road. Finally,
> it would allow us to more easily verify that we are in fact API compatible.
>
> *Can we use AudienceInterface?*
> HBase 0.94 can be compiled against both hadoop 0.2x, 1.x, and 2.0.x. In the
> case of 0.2x, the AudienceInterface classes were not bundled. Therefore, we
> cannot expect HBase 0.94 to support it. For that reason, I think JavaDoc
> might be better.
> On the other hand, perhaps we might just want to bundle AudienceInterface
> with 0.94 going forward? Then we can have consistent annotations in 0.94,
> 0.95, and 0.96 without worrying about the hadoop version.
>
> Please correct me if I'm wrong about any of the above.
>
> *Clarification of RPC compatibility:*
> We care about RPC compatibility when we create clients that bundle their
> dependency jars with them. These jars are used to form a request that is
> executed on a remote machine (i.e. the cluster). If the cluster is upgraded
> and no longer recognizes the command, then this will break RPC
> compatibility.
>
> *Clarification of Binary compatibility:*
> We care about binary compatibility when a client is created and compiled,
> and the jars on which is depends change. It should still be able to form
> requests using those jars. If the cluster is upgraded and the compiled
> client code cannot find a method it was depending on to be there, we break
> binary compatibility. A recent example is in 0.94.2, where the return type
> of HColumnDescriptor.setMaximumVersions was changed and those who upgraded
> received this error:
>
>     java.lang.NoSuchMethodError: org.apache.hadoop.hbase.**
> HColumnDescriptor.**setMaxVersions(I)V
>
> *What we currently have:*
> We have an @audience annotation set up in 0.95/0.96. In 0.94, I suggest
> either adding JavaDoc or pulling in the AudienceInterface annotation.
>
> *Suggested Javadoc language:*
> @custom.94_api
>
> *Granularity:*
> Just to the class level. The native java access level (e.g. public,
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Todd Lipcon 2013-04-08, 22:55
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Aleksandr Shulman 2013-04-09, 17:47
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Aleksandr Shulman 2013-04-16, 20:56
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Nick Dimiduk 2013-04-16, 21:14
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Aleksandr Shulman 2013-04-17, 18:01