To follow up on my on post, I think a straight-forward approach would be to make the `TypeExtractor.registerFactory` method public [1].
BTW, both the TypeInfo annotation [2] and TypeInfoFactory [3] itself refer to this method in the JavaDoc. However, besides these mentions I was not able to find any actual usage of `registerFactory` in the Flink codebase, so I am not sure when and where the method is actually invoked to register the annotated classes. [1] https://github.com/apache/flink/blob/e5d62da2c98ad9c6a5ca9c0782a7fea8a01d639a/flink-core/src/main/java/org/apache/flink/api/java/typeutils/TypeExtractor.java#L124-L144 [2] https://github.com/apache/flink/blob/e5d62da2c98ad9c6a5ca9c0782a7fea8a01d639a/flink-core/src/main/java/org/apache/flink/api/common/typeinfo/TypeInfo.java [2] https://github.com/apache/flink/blob/e5d62da2c98ad9c6a5ca9c0782a7fea8a01d639a/flink-core/src/main/java/org/apache/flink/api/common/typeinfo/TypeInfoFactory.java On Sat, Oct 8, 2016 at 4:00 PM Alexander Alexandrov < alexander.s.alexand...@gmail.com> wrote: I wanted to open this directly as a JIRA to follow-up on FLINK-3042, however my account (aalexandrov) does not seem to have the necessary privileges, so I will post this to the dev list instead. The current approach for registration of custom `TypeInformation` implementations which relies exclusively on annotations. Consequently, it will be very tedious to create a custom `TypeInformation` for types that are pulled and used within a project from an external library. For example, if I have a project structure such as ``` my-project // uses FancyContainer<A> `- flink-core `- ext-library // defines FancyContainer<A> ``` I will not be able to modify `FancyContainer.java`. A workaround that might work (I have not tested it yet) is to use `javassist` to attach the annotation prior to job assembly, but IMHO a much clearer solution would be to extend the `ExecutionEnvironment` with something like ```java env.getConfig().registerTypeInfoFactory(Class<?> type, Class<? extends TypeInfofactory<?>> factory) ``` Regards, Alexander
