Status

Current state: Under Discussion

Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]

JIRA: here [Change the link from KAFKA-1 to your own ticket]

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

The base class for all Source and Sink connectors is the org.apache.kafka.connect.connector.Connector abstract class. This class defines a few abstract methods (e.g. void start(Map<String, String> props) and void stop()) that are then implemented by Connectors and are invoked as part of their lifecycle.

As connectors interact with external systems, they sometimes need to provision external resources. We can think of a Sink connector that creates new queues in the Messaging System it wants to write messages to; an Object Store Sink connector that creates new buckets to store its messages; a Source connector that activates an account before requesting data from a source system. A more concrete example is a source connector that audits database changes by creating an "audit" table and database triggers which inserts the row-level updates to that table. In many cases, creating these resources is an idempotent operation. In other cases, the targeted system can be queried beforehand, and resources are provisioned only if they not exist.

The connector void start(Map<String, String> props) method is invoked when the connector is first started, or when it is restarted by the Worker (e.g. when the connector configuration changes). Similarly, the void stop() method is invoked when the connector is stopped by the Worker (e.g.  (for example, when the connector configuration changes).

ese are just a small and triggers  and  and   creating new queues on the Some connectors perform  a connector starts, it can perform ome connectors  creating new connectors, the 've some custom connectors that require provisioning external resources 

(think of creating queues, S3 buckets, or activating accounts) when the 

connector instance is created, but also need to cleanup these resources 

(delete, deactivate) when the connector instance is deleted.

  entry points for Connector implementations ,he a new connector is created, or an the problems you are trying to solve.

Public Interfaces

Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.

A public interface is any change to the following:

• Binary log format

• The network protocol and api behavior

• Any class in the public packages under clientsConfiguration, especially client configuration

  • org/apache/kafka/common/serialization

  • org/apache/kafka/common

  • org/apache/kafka/common/errors

  • org/apache/kafka/clients/producer

  • org/apache/kafka/clients/consumer (eventually, once stable)

• Monitoring

• Command line tools and arguments

• Anything else that will likely break existing users in some way when they upgrade

Proposed Changes

Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.

Compatibility, Deprecation, and Migration Plan

• What impact (if any) will there be on existing users?
• If we are changing behavior how will we phase out the older behavior?
• If we need special migration tools, describe them here.
• When will we remove the existing behavior?

Test Plan

Describe in few sentences how the KIP will be tested. We are mostly interested in system tests (since unit-tests are specific to implementation details). How will we know that the implementation works as expected? How will we know nothing broke?

Rejected Alternatives

If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.