[GitHub] nifi pull request: NIFI-989: Support size() operation in distribut...

[markap14 <gi...@git.apache.org>]

Github user markap14 commented on the pull request:

    https://github.com/apache/nifi/pull/94#issuecomment-144783629
  
    @joemeszaros the concern that I have with the notion of the ExtendedDistributedMapCacheClient is that once that is released, it will have the same caveats as the DistributedMapCacheClient - others can extend it, so we cannot change the interface in a non-backward-compatible way once we release it.
    
    I think if there are specific methods that we think will be added, then we need to implement those before we release the service. Otherwise, in order to add new methods to the ExtendedDistributedMapCacheClient we would need to create yet another interface that extends that one. This is all done because we consider the Standard Services API to be "public interfaces" so that once they are out there, we have no idea who has implemented them. As a result, if we change them, even if we update all of the code in Apache NiFi, we may be breaking someone else's "private" implementation.
    
    In theory, though, this will become a lot less painful once we move to 1.0.0 because I believe the intent is to move to Java 8, which means that we can include default implementations in the interfaces. As a result, we could potentially add new methods to interfaces as long as they can be implemented using existing methods.


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