Now that Kafka 0.10 has been released I would like to start work on the new protocol messages and client implementation for KIP-4. In order to break up the discussion and feedback I would like to continue breaking up the content in to smaller pieces.
This discussion thread is for the CreateTopic request/response and server side implementation. Details for this implementation can be read here: https://cwiki.apache.org/confluence/display/KAFKA/KIP-4+-+Command+line+and+centralized+administrative+operations#KIP-4-Commandlineandcentralizedadministrativeoperations-CreateTopicRequest I have included the exact content below for clarity: > Create Topic Request (KAFKA-2945 > <https://issues.apache.org/jira/browse/KAFKA-2945>) > > > CreateTopic Request (Version: 0) => [create_topic_requests] timeout > create_topic_requests => topic partitions replication_factor > [replica_assignment] [configs] > topic => STRING > partitions => INT32 > replication_factor => INT32 > replica_assignment => partition_id [replicas] > partition_id => INT32 > replicas => INT32 > configs => config_key config_value > config_key => STRING > config_value => STRING > timeout => INT32 > > CreateTopicRequest is a batch request to initiate topic creation with > either predefined or automatic replica assignment and optionally topic > configuration. > > Request semantics: > > 1. Must be sent to the controller broker > 2. Multiple instructions for the same topic in one request will be > silently ignored, only the last from the list will be executed. > - This is because the list of topics is modeled server side as a > map with TopicName as the key > 3. The principle must be authorized to the "Create" Operation on the > "Cluster" resource to create topics. > - Unauthorized requests will receive a ClusterAuthorizationException > 4. > > Only one from ReplicaAssignment or (Partitions + ReplicationFactor), can > be defined in one instruction. If both parameters are specified - > ReplicaAssignment takes precedence. > - In the case ReplicaAssignment is defined number of partitions and > replicas will be calculated from the supplied ReplicaAssignment. > - In the case of defined (Partitions + ReplicationFactor) replica > assignment will be automatically generated by the server. > - One or the other must be defined. The existing broker side auto > create defaults will not be used > (default.replication.factor, num.partitions). The client implementation > can > have defaults for these options when generating the messages. > 5. Setting a timeout > 0 will allow the request to block until the > topic metadata is "complete" on the controller node. > - Complete means the topic metadata has been completely populated > (leaders, replicas, ISRs) > - If a timeout error occurs, the topic could still be created > successfully at a later time. Its up to the client to query for the > state > at that point. > 6. The request is not transactional. > 1. If an error occurs on one topic, the other could still be > created. > 2. Errors are reported independently. > > QA: > > - Why is CreateTopicRequest a batch request? > - Scenarios where tools or admins want to create many topics should > be able to with fewer requests > - Example: MirrorMaker may want to create the topics downstream > - What happens if some topics error immediately? Will it > return immediately? > - The request will block until all topics have either been created, > errors, or the timeout has been hit > - There is no "short circuiting" where 1 error stops the other > topics from being created > - Why implement "partial blocking" instead of fully async of fully > consistent? > - See Cluster Consistent Blocking > > <https://cwiki.apache.org/#KIP-4-Commandlineandcentralizedadministrativeoperations-clusterconsistentblocking> > below > - Why require the request to go to the controller? > - The controller is responsible for the cluster metadata and > its propagation > - See Request Forwarding > > <https://cwiki.apache.org/#KIP-4-Commandlineandcentralizedadministrativeoperations-request> > below > > Create Topic Response > > > CreateTopic Response (Version: 0) => [topic_error_codes] > topic_error_codes => topic error_code > topic => STRING > error_code => INT16 > > CreateTopicResponse contains a map between topic and topic creation > result error code (see New Protocol Errors > <https://cwiki.apache.org/confluence/display/KAFKA/KIP-4+-+Command+line+and+centralized+administrative+operations#KIP-4-Commandlineandcentralizedadministrativeoperations-NewProtocolErrors> > ). > A sample PR is on github (https://github.com/apache/kafka/pull/1489) though it could change drastically based on the feedback here. Thanks, Grant -- Grant Henke Software Engineer | Cloudera gr...@cloudera.com | twitter.com/gchenke | linkedin.com/in/granthenke
