I agree, Experimental rather suggests unstable behavior than potentially changing interfaces. +1 for renaming to @PublicEvolving.
Other opinions on strictly annotating all public interfaces with @Public / @PublicEvolving and defaulting to @Internal for all remaining interfaces? 2016-02-06 15:27 GMT+01:00 Stephan Ewen <se...@apache.org>: > What "Experimental" is really saying is "Public, but not API stable". In > that sense, "Internal" is not suitable, as it suggests that a method will > never be public. > > What would you think of renaming "Experimental" to "PublicEvolving" ? > > That would carry pretty much explicitly the meaning that it is intended for > public use, the basic concept will stay, but it may change a bit (code > using that may be adjusted a bit in the future). In contrast "Experimental" > sounds to me like "no idea if that class/feature is going to be there in > the future". > > What do you think? > > Stephan > > > On Sat, Feb 6, 2016 at 3:17 PM, Stephan Ewen <se...@apache.org> wrote: > > > Hi! > > > > These suggestions sound good in general. > > > > I am wondering if "Experimental" is not the wrong word here, because most > > of the things are not experimental, but just possibly subject to slight > > changes (though API breaking). > > > > Experimental has the connotation that something is unstable (execution > > wise) and should best be avoided altogether. > > If half of the Flink code base is marked "Experimental", it seems to > > contradict that this is actually in 1.0 shape. > > > > I actually like the term "Internal" that was also suggested. It pretty > > much says what we actually want to say: A certain method or class is not > > declared part of the public API, but as of now only internal API. > > > > Greetings, > > Stephan > > > > > > > > On Fri, Feb 5, 2016 at 8:38 PM, Fabian Hueske <fhue...@gmail.com> wrote: > > > >> Hi, > >> > >> @Experimental and @Internal have the class scope, because we need to be > >> able to mark internal classes of @Public classes as experimental or > >> internal. > >> > >> In some cases we annotated classes as @Public and all (or most) methods > as > >> @Experimental, to indicate that a class can be used, but its internals > >> might change. > >> For example TypeInformation is a public class (and many classes that > >> extend > >> this class) but most methods are @Experimental to allow users to used a > >> TypeInformation as is, but keep the freedom to change the internals. If > >> you > >> find something that does not look correct, please start a discussion > >> about. > >> The annotations can still be changed before the 1.0 release. > >> > >> I agree with Max that annotating more classes with @Experimental (not > only > >> inner classes) would be a good idea. > >> IMO, we should annotate all classes that belong to the user-facing API > >> with > >> either @Public or @Experimental. This would mean that all non-annotated > >> classes are not part of the API and must be considered as internal. I > >> believe this would avoid a lot of uncertainty and also easy the > annotation > >> management as a whole. For instance, we can more easily check how the > API > >> (stable and experimental) changed between releases. > >> > >> Cheers, Fabian > >> > >> 2016-02-05 17:24 GMT+01:00 Maximilian Michels <m...@apache.org>: > >> > >> > Hi Robert, > >> > > >> > Thanks a lot for all the work of going through the classes. At first > >> > sight, the classes look quite well chosen. > >> > > >> > One question concerning the @Public, @Experimental, and @Internal > >> > annotations: > >> > > >> > @Public may only be used for classes or interfaces. @Experimental or > >> > @Internal are used for marking methods in @Public classes only? If > >> > that is the case, we should restrict the annotations to this scope via > >> > @Target. The current master also permits to tag classes with > >> > @Experimental or @Internal. > >> > > >> > Marking classes with @Experimental might actually make sense. What was > >> > the rational behind always declaring a class public first to restrict > >> > its methods to internal or experimental? > >> > > >> > Cheers, > >> > Max > >> > > >> > On Fri, Feb 5, 2016 at 3:07 PM, Robert Metzger <rmetz...@apache.org> > >> > wrote: > >> > > Hi, > >> > > > >> > > tl;dr: we now have @Public, @Internal, @Experimental annotations. > >> Check > >> > > your stuff before the release! > >> > > > >> > > Fabian and I spend some time the last weeks to annotate all classes > we > >> > > consider to be userfacing and stable with the "*@Public*" > annotation. > >> I > >> > > just pushed those changes to master. > >> > > > >> > > There is also an annotation "*@Internal*" for marking interfaces > users > >> > > should not use because they are internal to the system (for example > >> > > "DataStream.getId()"). > >> > > > >> > > The annotation "*@Experimental*" marks unstable methods within > stable > >> > > classes (for example SingleOutputStreamOperator.uid()). > >> > > Also note that we should also annotate @Deprecated methods with > >> > > @Experimental so that they are not part of the stable interface > (this > >> > works > >> > > only before the 1.0 release). I checked that all current @Deprecated > >> > > annotations are excluded. > >> > > > >> > > > >> > > *I would like to ask everyone to spend some time before the 1.0 > >> release > >> > to > >> > > go through some core classes and see if there is anything we > forgot.* > >> > > *We will not be able to touch methods and classes which are public > >> after > >> > > the 1.0 release.* > >> > > > >> > > Some areas where I feel we should check closely are the following: > >> > > - InputFormats > >> > > - State-related classes > >> > > - Windowing related classes > >> > > - DataStream API (global() / forward(); output to files; ... ). > >> > > > >> > > Fabian and I also realized that there are some downsides to this > >> > annotation > >> > > approach. > >> > > a) By not annotating all classes, its easy to forget some classes. > And > >> > its > >> > > not obvious to users that "no annotation" means "not public". > >> > > > >> > > b) For example the "SourceFunction.SourceContext" interface is > @Public > >> > > because users use the methods of the interface. > >> > > However, the underlying implementations are internal to Flink (users > >> will > >> > > most likely not implement their own SourceContexts). Adding a new > >> method > >> > to > >> > > the SourceContext interface will break its compatibilty (because > users > >> > > would need to implement the new method), however, for API users it > >> does > >> > not > >> > > matter when we are adding new methods. > >> > > We decided to make the interface @Public, but we added a comment > >> > explaining > >> > > the issue. > >> > > If we want to add a method after the 1.0 release, we can define an > >> > exclude > >> > > in the maven plugin which enforces the interface stability. > >> > > > >> > > > >> > > For making the whole annotation analysis business a bit easier, I'm > >> > > currently working on a little tool to output a list of public > classes > >> and > >> > > methods. I'll post that on the mailing list at a later point. > >> > > > >> > > Regards, > >> > > Robert > >> > > >> > > > > >
