[GitHub] [nifi] markap14 commented on pull request #5279: NIFI-8993 Added registry to scriptedtransformrecord.

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markap14 commented on pull request #5279:
URL: https://github.com/apache/nifi/pull/5279#issuecomment-915298187


   @MikeThomsen I'm not sure I'm a fan of this approach to be honest, for a couple a reasons.
   
   - The point of ScriptedTransformRecord, as opposed to something like ExecuteScript, is to keep it as dead simple as possible to perform scripted modifications to records. There's also another PR up that we're working through (https://github.com/apache/nifi/pull/4948) to add more record-based scripted components. We need to be ruthlessly diligent about what we introduce here. We really want simplicity & usability here over power. ExecuteScript, etc. give us power, while this should yield simplicity.
   - If we do introduce Registry, we've perhaps started down a slipper slope. What happens when someone then needs a different type of Controller Service? A Record Lookup Service, for example. Do we then add another property for RecordLookupService? What if we need a StringLookupService instead of a RecordLookupService? Do we add yet another property for that? Now this is far from simple.
   - The notion of a "RegistryHelper" is nebulous. Whatever gets injected in, if it's a complex object, needs to have a properly formed API/interface with sufficient JavaDocs that explain exactly how it is used, and we need to protect that API/interface as new versions come out & things evolve.
   
   That being said, I do see benefit in having the ability to reference Controller Services.
   So what I would propose would be to attack this a bit differently. Instead of adding a "Schema Registry" property we could allow for user-defined properties. The name of the property would be the variable binding for the script. The dynamic property descriptor would then identify a Controller Service of type ControllerService. I.e., any Controller Service. In this way, a user can inject in 1 or more Controller Services of any type. For example, if I added a property named "MyService" and chose a SchemaRegistry as the property value, then my script would be able to reference `this.MyService` and that would be the actual Schema Registry controller service.
   
   Thoughts on this approach?


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