Hi Jing, Thanks for the feedback. Please see the answers to your questions below:
*"Always add a "Since X.X.X" comment to indicate when was a class / > interface / method marked as deprecated."* > Could you describe it with a code example? Do you mean Java comments? It is just a comment such as "Since 1.18. Use X <https://kafka.apache.org/31/javadoc/org/apache/kafka/clients/admin/Admin.html#incrementalAlterConfigs(java.util.Map)>XX instead.". And we can then look it up in the deprecated list[1] in each release and see which method should / can be deprecated. *"At least 1 patch release for the affected minor release for > Experimental APIs"* > The rule is absolutely right. However, afaiac, deprecation is different as > modification. As a user/dev, I would appreciate, if I do not need to do any > migration work for any deprecated API between patch releases upgrade. BTW, > if experimental APIs are allowed to change between patches, could we just > change them instead of marking them as deprecated and create new ones to > replace them? Deprecating an API is just a more elegant way of replacing an API with a new one. The only difference between the two is whether the old API is kept and coexists with the new API for some releases or not. For end users, deprecation-then-remove is much more friendly than direct replacement. 1. How to make sure the new APIs cover all functionality, i.e. backward > compatible, before removing the deprecated APIs? Since the > functionalities could only be built with the new APIs iteratively, there > will be a while (might be longer than the migration period) that the new > APIs are not backward compatible with the deprecated ones. This is orthogonal to the deprecation process, and may not even be required in some cases if the function changes by itself. But in general, this relies on the developer to decide. A simple test on readiness is to see if all the UT / IT cases written with the old API can be migrated to the new one and still work. If the new API is not ready, we probably should not deprecate the old one to begin with. 2. Is it allowed to remove the deprecated APIs after the defined migration > period expires while the new APis are still not backward compatible? By "backwards compatible", do you mean functionally equivalent? If the new APIs are designed to be not backwards compatible, then removing the deprecated source code is definitely allowed. If we don't think the new API is ready to take over the place for the old one, then we should wait. The migration period is the minimum time we have to wait before removing the source code. A longer migration period is OK. 3. For the case of core API upgrade with downstream implementations, e.g. > connectors, What is the feasible deprecation strategy? Option1 bottom-up: > make sure the downstream implementation is backward compatible before > removing the deprecated core APIs. Option2 top-down: once the downstream > implementation of new APIs works fine, we can remove the deprecated core > APIs after the migration period expires. The implementation of the > deprecated APIs will not get any further update in upcoming releases(it has > been removed). There might be some missing features in the downstream > implementation of new APIs compared to the old implementation. Both options > have their own pros and cons. The downstream projects such as connectors in Flink should also follow the migration path we tell our users. i.e. If there is a cascading backwards incompatible change in the connectors due to a backwards incompatible change in the core, and as a result a longer migration period is required, then I think we should postpone the removal of source code. But in general, we should be able to provide the same migration period in the connectors as the flink core, if the connectors are upgraded to the latest version of core promptly. Thanks, Jiangjie (Becket) Qin [1] https://nightlies.apache.org/flink/flink-docs-master/api/java/deprecated-list.html On Wed, Jun 14, 2023 at 1:15 AM Jing Ge <j...@ververica.com.invalid> wrote: > > This is by design. Most of these are @Public APIs that we had to carry > > around until Flink 2.0, because that was the initial guarantee that we > > gave people. > > > > True, I knew @Public APIs could not be removed before the next major > release. I meant house cleaning without violation of these annotations' > design concept. i.e especially cleaning up for @PublicEvolving APIs since > they are customer-facing. Regular cleaning up with all other @Experimental > and @Internal APIs would be even better, if there might be some APIs marked > as @deprecated. > > Best regards, > Jing > > > > On Tue, Jun 13, 2023 at 4:25 PM Chesnay Schepler <ches...@apache.org> > wrote: > > > On 13/06/2023 12:50, Jing Ge wrote: > > > One major issue we have, afaiu, is caused by the lack of > > housekeeping/house > > > cleaning, there are many APIs that were marked as deprecated a few > years > > > ago and still don't get removed. Some APIs should be easy to remove and > > > others will need some more clear rules, like the issue discussed at > [1]. > > > This is by design. Most of these are @Public APIs that we had to carry > > around until Flink 2.0, because that was the initial guarantee that we > > gave people. > > > > > > As for the FLIP, I like the idea of explicitly writing down a > > deprecation period for APIs, particularly PublicEvolving ones. > > For Experimental I don't think it'd be a problem if we could change them > > right away, > > but looking back a bit I don't think it hurts us to also enforce some > > deprecation period. > > 1 release for both of these sound fine to me. > > > > > > My major point of contention is the removal of Public APIs between minor > > versions. > > This to me would a major setback towards a simpler upgrade path for > users. > > If these can be removed in minor versions than what even is a major > > release? > > The very definition we have for Public APIs is that they stick around > > until the next major one. > > Any rule that theoretically allows for breaking changes in Public API in > > every minor release is in my opinion not a viable option. > > > > > > The "carry recent Public APIs forward into the next major release" thing > > seems to presume a linear release history (aka, if 2.0 is released after > > 1.20, then there will be no 1.21), which I doubt will be the case. The > > idea behind it is good, but I'd say the right conclusion would be to not > > make that API public if we know a new major release hits in 3 months and > > is about to modify it. With a regular schedule for major releases this > > wouldn't be difficult to do. > > >
