Multiple kafka topic having same data model

[RouxAntoine]

The common practice to link avro schema to topic is to use a subject.
The subject to topic link can follow different naming strategy: TopicNameStrategy, RecordNameStrategy, TopicRecordNameStrategy (more details here for example https://developer.confluent.io/courses/schema-registry/schema-subjects/)

This indirection allow to attached a same avro schema to multiple topic.
How can we reproduce with this data contract specification ?

what is the link between model and topic if there is multiple model in a same datacontract ?
Do you think that in future version the top level topic field would be a complex object describing relation between model and topic ?

regards;

[simonharrer]

Typical: 1 data contract with 1 model for 1 topic

models:
  orders:
    type: topic
servers:
  my-server:
    type: kafka
    topic: topic.orders.v1

Possible: 1 data contract with n models for n topics (1 model for each topic). This is similar to having many tables in a schema.

models:
  orders:
    type: topic
  line_items:
    type: topic
servers:
  my-server:
    type: kafka
    topic: topic.orders.v1, topic.line_items.v1

You can use links from a model to its avro schema, if that helps.

models:
  orders:
    type: topic
    links:
      avroSchemaUrl: ...

What do you mean with "top level topic field"?

[RouxAntoine]

Hello @simonharrer thanks for answer,

by top level topic field -> I mean the one defined in the server[*].topic so your response is perfectly on track.

The links seems what I search becaure we have lot a of topic, moreover I don't see this property in the doc of the model object https://datacontract.com/#model-object.

If I understand properly we can defined our topic as a model.

as an example today our model contain this data structure (converted to an avro with export feature):

model:
  Member:
    type: object
    description: A dummy member event
    namespace: com.enterprise.business-unit.domain.avro.v1
    fields:
      memberId:
        description: Unique identifier of a member
        $ref: "#/definitions/memberId"
      memberName:
        type: string
        required: false
        description: Name of a user
        config:
          avroDefault: null

and we can add in same file

model:
  my.topic.name.complete:
    type: topic
    links:
      avroSchemaUrl: ...

but when we write our datacontract the schema url is not already declare and known.

[simonharrer]

but when we write our datacontract the schema url is not already declare and known.

What is your question here?

[RouxAntoine]

Yes sorry not clear,

What we search is how to link a model to a topic ?
The solution you propose me with the links>avroSchemaUrl property is to link a topic to a schema url.
Which can't be exploited because we don't have schema url.

Then the second question is where is the model[*]>links>avroSchemaUrl in the documentation https://datacontract.com/#model-object ? so that I can try to search other acceptable solution for my usecase.

thanks for your insight

[simonharrer]

A model is linked to a topic by name. You can use

models:
  orders: # default link
    config:
      physicalName: real-world-topic-name # override

[RouxAntoine]

ok good and the config can contain an array https://github.com/datacontract/datacontract-specification/blob/main/datacontract.schema.json#L722
This is perfect we will use model[*]>config>topics: ["topic-1", "topic-2"] for our use case.
Your remark that model is link to a topic by name is also interresting. In my case not possible because this is a one to many relation but can be good in some situation.
Thanks I will close the discussion because seem good to me.