Hi John, I’m really sorry for the confusion. I cloned that JIRA ticket from an old one about introducing UUID Serde, and I guess was too hasty while editing the copy to notice the mistake. Just edited the ticket. Sorry for any inconvenience .
As per comparator, I agree. Let’s make user be responsible for implementing comparable interface. I was just thinking to make the serde a little more flexible (i.e. let user decide in which order records is going to be inserted into a change log topic). Thank you! Best, Daniyar Yeralin > On May 6, 2019, at 5:37 PM, John Roesler <j...@confluent.io> wrote: > > Hi Daniyar, > > Thanks for the proposal! > > If I understand the point about the comparator, is it just to capture the > generic type parameter? If so, then anything that implements a known > interface would work just as well, right? I've been considering adding > something like the Jackson TypeReference (or similar classes in many other > projects). Would this be a good time to do it? > > Note that it's not necessary to actually require that the captured type is > Comparable (as this proposal currently does), it's just a way to make sure > there is some method that makes use of the generic type parameter, to force > the compiler to capture the type. > > Just to make sure I understand the motivation... You expressed a desire to > be able to serialize UUIDs, which I didn't follow, since there is a > built-in UUID serde: org.apache.kafka.common.serialization.Serdes#UUID, and > also, a UUID isn't a List. Did you mean that you need to use *lists of* > UUIDs? > > Thanks, > -John > > On Mon, May 6, 2019 at 11:49 AM Development <d...@yeralin.net> wrote: > >> Hello, >> >> Starting a discussion for KIP-466 adding support for List Serde. PR is >> created under https://github.com/apache/kafka/pull/6592 < >> https://github.com/apache/kafka/pull/6592> >> >> There are two topics I would like to discuss: >> 1. Since type for List serve needs to be declared before hand, I could not >> create a static method for List Serde under >> org.apache.kafka.common.serialization.Serdes. I addressed it in the KIP: >> P.S. Static method corresponding to ListSerde under >> org.apache.kafka.common.serialization.Serdes (something like static public >> Serde<List<T>> List() {...} inorg.apache.kafka.common.serialization.Serdes) >> class cannot be added because type needs to be defined beforehand. That's >> why one needs to create List Serde in the following fashion: >> new Serdes.ListSerde<String>(Serdes.String(), >> Comparator.comparing(String::length)); >> (can possibly be simplified by declaring import static >> org.apache.kafka.common.serialization.Serdes.ListSerde) >> >> 2. @miguno Michael G. Noll <https://github.com/miguno> is questioning >> whether I need to pass a comparator to ListDeserializer. This certainly is >> not required. Feel free to add your input: >> https://github.com/apache/kafka/pull/6592#discussion_r281152067 >> >> Thank you! >> >> Best, >> Daniyar Yeralin >> >>> On May 6, 2019, at 11:59 AM, Daniyar Yeralin (JIRA) <j...@apache.org> >> wrote: >>> >>> Daniyar Yeralin created KAFKA-8326: >>> -------------------------------------- >>> >>> Summary: Add List<T> Serde >>> Key: KAFKA-8326 >>> URL: https://issues.apache.org/jira/browse/KAFKA-8326 >>> Project: Kafka >>> Issue Type: Improvement >>> Components: clients, streams >>> Reporter: Daniyar Yeralin >>> >>> >>> I propose adding serializers and deserializers for the java.util.List >> class. >>> >>> I have many use cases where I want to set the key of a Kafka message to >> be a UUID. Currently, I need to turn UUIDs into strings or byte arrays and >> use their associated Serdes, but it would be more convenient to serialize >> and deserialize UUIDs directly. >>> >>> I believe there are many use cases where one would want to have a List >> serde. Ex. [ >> https://stackoverflow.com/questions/41427174/aggregate-java-objects-in-a-list-with-kafka-streams-dsl-windows], >> [ >> https://stackoverflow.com/questions/46365884/issue-with-arraylist-serde-in-kafka-streams-api >> ] >>> >>> >>> >>> KIP Link: [ >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-466%3A+Add+support+for+List%3CT%3E+serialization+and+deserialization >> ] >>> >>> >>> >>> -- >>> This message was sent by Atlassian JIRA >>> (v7.6.3#76005) >> >>
