On Wed, Mar 30, 2016 at 6:21 PM, Gwen Shapira <g...@confluent.io> wrote:
> Ismael, can you detail how the Optional approach would work in the wire > protocol? It sounds good, but I'm unclear on what this would look like on > the wire. > In the wire protocol, we would still use a size of -1 like we normally do for nullable strings and nullable bytes. So, it's still a bit magical, but efficient and associated with the right field (which avoids some invalid states that are possible if we use two fields). In other words, each implementation of the protocol is responsible for figuring out an idiomatic and hopefully safe way to represent the absence of a value. In Java (Scala would be similar) we would convert this to an Optional<List<String>> to make it clear that the value could be absent (and avoid NPEs). The fact that absence of a value means "all topics" makes sense if one thinks about that field as a filter (absence of a value means no filter). I can see pros and cons for each approach, personally. :) Ismael
