Kafka protocol guide

This document covers the wire protocol implemented in Kafka. It is meant to give a readable guide to the protocol that covers the available requests, their binary format, and the proper way to make use of them to implement a client. This document assumes you understand the basic design and terminology described here

• Preliminaries
  • Network
  • Partitioning and bootstrapping
  • Partitioning Strategies
  • Batching
  • Versioning and Compatibility
• The Protocol
  • Protocol Primitive Types
  • Notes on reading the request format grammars
  • Common Request and Response Structure
  • Message Sets
• Constants
  • Error Codes
  • Api Keys
• The Messages
• Some Common Philosophical Questions

Preliminaries

Network

Kafka uses a binary protocol over TCP. The protocol defines all apis as request response message pairs. All messages are size delimited and are made up of the following primitive types.

The client initiates a socket connection and then writes a sequence of request messages and reads back the corresponding response message. No handshake is required on connection or disconnection. TCP is happier if you maintain persistent connections used for many requests to amortize the cost of the TCP handshake, but beyond this penalty connecting is pretty cheap.

The client will likely need to maintain a connection to multiple brokers, as data is partitioned and the clients will need to talk to the server that has their data. However it should not generally be necessary to maintain multiple connections to a single broker from a single client instance (i.e. connection pooling).

The server guarantees that on a single TCP connection, requests will be processed in the order they are sent and responses will return in that order as well. The broker's request processing allows only a single in-flight request per connection in order to guarantee this ordering. Note that clients can (and ideally should) use non-blocking IO to implement request pipelining and achieve higher throughput. i.e., clients can send requests even while awaiting responses for preceding requests since the outstanding requests will be buffered in the underlying OS socket buffer. All requests are initiated by the client, and result in a corresponding response message from the server except where noted.

The server has a configurable maximum limit on request size and any request that exceeds this limit will result in the socket being disconnected.

Partitioning and bootstrapping

Kafka is a partitioned system so not all servers have the complete data set. Instead recall that topics are split into a pre-defined number of partitions, P, and each partition is replicated with some replication factor, N. Topic partitions themselves are just ordered "commit logs" numbered 0, 1, ..., P.

All systems of this nature have the question of how a particular piece of data is assigned to a particular partition. Kafka clients directly control this assignment, the brokers themselves enforce no particular semantics of which messages should be published to a particular partition. Rather, to publish messages the client directly addresses messages to a particular partition, and when fetching messages, fetches from a particular partition. If two clients want to use the same partitioning scheme they must use the same method to compute the mapping of key to partition.

These requests to publish or fetch data must be sent to the broker that is currently acting as the leader for a given partition. This condition is enforced by the broker, so a request for a particular partition to the wrong broker will result in an the NotLeaderForPartition error code (described below).

How can the client find out which topics exist, what partitions they have, and which brokers currently host those partitions so that it can direct its requests to the right hosts? This information is dynamic, so you can't just configure each client with some static mapping file. Instead all Kafka brokers can answer a metadata request that describes the current state of the cluster: what topics there are, which partitions those topics have, which broker is the leader for those partitions, and the host and port information for these brokers.

In other words, the client needs to somehow find one broker and that broker will tell the client about all the other brokers that exist and what partitions they host. This first broker may itself go down so the best practice for a client implementation is to take a list of two or three urls to bootstrap from. The user can then choose to use a load balancer or just statically configure two or three of their kafka hosts in the clients.

The client does not need to keep polling to see if the cluster has changed; it can fetch metadata once when it is instantiated cache that metadata until it receives an error indicating that the metadata is out of date. This error can come in two forms: (1) a socket error indicating the client cannot communicate with a particular broker, (2) an error code in the response to a request indicating that this broker no longer hosts the partition for which data was requested.

1. Cycle through a list of "bootstrap" kafka urls until we find one we can connect to. Fetch cluster metadata.
2. Process fetch or produce requests, directing them to the appropriate broker based on the topic/partitions they send to or fetch from.
3. If we get an appropriate error, refresh the metadata and try again.

Partitioning Strategies

As mentioned above the assignment of messages to partitions is something the producing client controls. That said, how should this functionality be exposed to the end-user?

Partitioning really serves two purposes in Kafka:

1. It balances data and request load over brokers
2. It serves as a way to divvy up processing among consumer processes while allowing local state and preserving order within the partition. We call this semantic partitioning.

For a given use case you may care about only one of these or both.

To accomplish simple load balancing a simple approach would be for the client to just round robin requests over all brokers. Another alternative, in an environment where there are many more producers than brokers, would be to have each client chose a single partition at random and publish to that. This later strategy will result in far fewer TCP connections.

Semantic partitioning means using some key in the message to assign messages to partitions. For example if you were processing a click message stream you might want to partition the stream by the user id so that all data for a particular user would go to a single consumer. To accomplish this the client can take a key associated with the message and use some hash of this key to choose the partition to which to deliver the message.

Batching

Our apis encourage batching small things together for efficiency. We have found this is a very significant performance win. Both our API to send messages and our API to fetch messages always work with a sequence of messages not a single message to encourage this. A clever client can make use of this and support an "asynchronous" mode in which it batches together messages sent individually and sends them in larger clumps. We go even further with this and allow the batching across multiple topics and partitions, so a produce request may contain data to append to many partitions and a fetch request may pull data from many partitions all at once.

The client implementer can choose to ignore this and send everything one at a time if they like.

Versioning and Compatibility

The protocol is designed to enable incremental evolution in a backward compatible fashion. Our versioning is on a per API basis, each version consisting of a request and response pair. Each request contains an API key that identifies the API being invoked and a version number that indicates the format of the request and the expected format of the response.

The intention is that clients will support a range of API versions. When communicating with a particular broker, a given client should use the highest API version supported by both and indicate this version in their requests.

The server will reject requests with a version it does not support, and will always respond to the client with exactly the protocol format it expects based on the version it included in its request. The intended upgrade path is that new features would first be rolled out on the server (with the older clients not making use of them) and then as newer clients are deployed these new features would gradually be taken advantage of.

Our goal is primarily to allow API evolution in an environment where downtime is not allowed and clients and servers cannot all be changed at once.

Currently all versions are baselined at 0, as we evolve these APIs we will indicate the format for each version individually.

Retrieving Supported API versions

In order to work against multiple broker versions, clients need to know what versions of various APIs a broker supports. The broker exposes this information since 0.10.0.0 as described in KIP-35. Clients should use the supported API versions information to choose the highest API version supported by both client and broker. If no such version exists, an error should be reported to the user.

The following sequence may be used by a client to obtain supported API versions from a broker.

1. Client sends ApiVersionsRequest to a broker after connection has been established with the broker. If SSL is enabled, this happens after SSL connection has been established.
2. On receiving ApiVersionsRequest, a broker returns its full list of supported ApiKeys and versions regardless of current authentication state (e.g., before SASL authentication on an SASL listener, do note that no Kafka protocol requests may take place on a SSL listener before the SSL handshake is finished). If this is considered to leak information about the broker version a workaround is to use SSL with client authentication which is performed at an earlier stage of the connection where the ApiVersionRequest is not available. Also, note that broker versions older than 0.10.0.0 do not support this API and will either ignore the request or close connection in response to the request.
3. If multiple versions of an API are supported by broker and client, clients are recommended to use the latest version supported by the broker and itself.
4. Deprecation of a protocol version is done by marking an API version as deprecated in the protocol documentation.
5. Supported API versions obtained from a broker are only valid for the connection on which that information is obtained. In the event of disconnection, the client should obtain the information from the broker again, as the broker might have been upgraded/downgraded in the mean time.

SASL Authentication Sequence

The following sequence is used for SASL authentication:

1. Kafka ApiVersionsRequest may be sent by the client to obtain the version ranges of requests supported by the broker. This is optional.
2. Kafka SaslHandshakeRequest containing the SASL mechanism for authentication is sent by the client. If the requested mechanism is not enabled in the server, the server responds with the list of supported mechanisms and closes the client connection. If the mechanism is enabled in the server, the server sends a successful response and continues with SASL authentication.
3. The actual SASL authentication is now performed. If SaslHandshakeRequest version is v0, a series of SASL client and server tokens corresponding to the mechanism are sent as opaque packets without wrapping the messages with Kafka protocol headers. If SaslHandshakeRequest version is v1, the SaslAuthenticate request/response are used, where the actual SASL tokens are wrapped in the Kafka protocol. The error code in the final message from the broker will indicate if authentication succeeded or failed.
4. If authentication succeeds, subsequent packets are handled as Kafka API requests. Otherwise, the client connection is closed.

For interoperability with 0.9.0.x clients, the first packet received by the server is handled as a SASL/GSSAPI client token if it is not a valid Kafka request. SASL/GSSAPI authentication is performed starting with this packet, skipping the first two steps above.

The Protocol

Protocol Primitive Types

The protocol is built out of the following primitive types.

Fixed Width Primitives

int8, int16, int32, int64 - Signed integers with the given precision (in bits) stored in big endian order.

Variable Length Primitives

bytes, string - These types consist of a signed integer giving a length N followed by N bytes of content. A length of -1 indicates null. string uses an int16 for its size, and bytes uses an int32.

Arrays

This is a notation for handling repeated structures. These will always be encoded as an int32 size containing the length N followed by N repetitions of the structure which can itself be made up of other primitive types. In the BNF grammars below we will show an array of a structure foo as [foo].

Notes on reading the request format grammars

The BNFs below give an exact context free grammar for the request and response binary format. The BNF is intentionally not compact in order to give human-readable name. As always in a BNF a sequence of productions indicates concatenation. When there are multiple possible productions these are separated with '|' and may be enclosed in parenthesis for grouping. The top-level definition is always given first and subsequent sub-parts are indented.

Common Request and Response Structure

All requests and responses originate from the following grammar which will be incrementally describe through the rest of this document:

RequestOrResponse => Size (RequestMessage | ResponseMessage)
Size => int32

Field	Description
message_size	The message_size field gives the size of the subsequent request or response message in bytes. The client can read requests by first reading this 4 byte size as an integer N, and then reading and parsing the subsequent N bytes of the request.

Message Sets

A description of the message set format can be found here. (KAFKA-3368)

Constants

Error Codes

We use numeric codes to indicate what problem occurred on the server. These can be translated by the client into exceptions or whatever the appropriate error handling mechanism in the client language. Here is a table of the error codes currently in use:

Error	Code	Retriable	Description
UNKNOWN_SERVER_ERROR	-1	False	The server experienced an unexpected error when processing the request
NONE	0	False
OFFSET_OUT_OF_RANGE	1	False	The requested offset is not within the range of offsets maintained by the server.
CORRUPT_MESSAGE	2	True	This message has failed its CRC checksum, exceeds the valid size, or is otherwise corrupt.
UNKNOWN_TOPIC_OR_PARTITION	3	True	This server does not host this topic-partition.
INVALID_FETCH_SIZE	4	False	The requested fetch size is invalid.
LEADER_NOT_AVAILABLE	5	True	There is no leader for this topic-partition as we are in the middle of a leadership election.
NOT_LEADER_FOR_PARTITION	6	True	This server is not the leader for that topic-partition.
REQUEST_TIMED_OUT	7	True	The request timed out.
BROKER_NOT_AVAILABLE	8	False	The broker is not available.
REPLICA_NOT_AVAILABLE	9	False	The replica is not available for the requested topic-partition
MESSAGE_TOO_LARGE	10	False	The request included a message larger than the max message size the server will accept.
STALE_CONTROLLER_EPOCH	11	False	The controller moved to another broker.
OFFSET_METADATA_TOO_LARGE	12	False	The metadata field of the offset request was too large.
NETWORK_EXCEPTION	13	True	The server disconnected before a response was received.
COORDINATOR_LOAD_IN_PROGRESS	14	True	The coordinator is loading and hence can't process requests.
COORDINATOR_NOT_AVAILABLE	15	True	The coordinator is not available.
NOT_COORDINATOR	16	True	This is not the correct coordinator.
INVALID_TOPIC_EXCEPTION	17	False	The request attempted to perform an operation on an invalid topic.
RECORD_LIST_TOO_LARGE	18	False	The request included message batch larger than the configured segment size on the server.
NOT_ENOUGH_REPLICAS	19	True	Messages are rejected since there are fewer in-sync replicas than required.
NOT_ENOUGH_REPLICAS_AFTER_APPEND	20	True	Messages are written to the log, but to fewer in-sync replicas than required.
INVALID_REQUIRED_ACKS	21	False	Produce request specified an invalid value for required acks.
ILLEGAL_GENERATION	22	False	Specified group generation id is not valid.
INCONSISTENT_GROUP_PROTOCOL	23	False	The group member's supported protocols are incompatible with those of existing members or first group member tried to join with empty protocol type or empty protocol list.
INVALID_GROUP_ID	24	False	The configured groupId is invalid
UNKNOWN_MEMBER_ID	25	False	The coordinator is not aware of this member.
INVALID_SESSION_TIMEOUT	26	False	The session timeout is not within the range allowed by the broker (as configured by group.min.session.timeout.ms and group.max.session.timeout.ms).
REBALANCE_IN_PROGRESS	27	False	The group is rebalancing, so a rejoin is needed.
INVALID_COMMIT_OFFSET_SIZE	28	False	The committing offset data size is not valid
TOPIC_AUTHORIZATION_FAILED	29	False	Not authorized to access topics: [Topic authorization failed.]
GROUP_AUTHORIZATION_FAILED	30	False	Not authorized to access group: Group authorization failed.
CLUSTER_AUTHORIZATION_FAILED	31	False	Cluster authorization failed.
INVALID_TIMESTAMP	32	False	The timestamp of the message is out of acceptable range.
UNSUPPORTED_SASL_MECHANISM	33	False	The broker does not support the requested SASL mechanism.
ILLEGAL_SASL_STATE	34	False	Request is not valid given the current SASL state.
UNSUPPORTED_VERSION	35	False	The version of API is not supported.
TOPIC_ALREADY_EXISTS	36	False	Topic with this name already exists.
INVALID_PARTITIONS	37	False	Number of partitions is invalid.
INVALID_REPLICATION_FACTOR	38	False	Replication-factor is invalid.
INVALID_REPLICA_ASSIGNMENT	39	False	Replica assignment is invalid.
INVALID_CONFIG	40	False	Configuration is invalid.
NOT_CONTROLLER	41	True	This is not the correct controller for this cluster.
INVALID_REQUEST	42	False	This most likely occurs because of a request being malformed by the client library or the message was sent to an incompatible broker. See the broker logs for more details.
UNSUPPORTED_FOR_MESSAGE_FORMAT	43	False	The message format version on the broker does not support the request.
POLICY_VIOLATION	44	False	Request parameters do not satisfy the configured policy.
OUT_OF_ORDER_SEQUENCE_NUMBER	45	False	The broker received an out of order sequence number
DUPLICATE_SEQUENCE_NUMBER	46	False	The broker received a duplicate sequence number
INVALID_PRODUCER_EPOCH	47	False	Producer attempted an operation with an old epoch. Either there is a newer producer with the same transactionalId, or the producer's transaction has been expired by the broker.
INVALID_TXN_STATE	48	False	The producer attempted a transactional operation in an invalid state
INVALID_PRODUCER_ID_MAPPING	49	False	The producer attempted to use a producer id which is not currently assigned to its transactional id
INVALID_TRANSACTION_TIMEOUT	50	False	The transaction timeout is larger than the maximum value allowed by the broker (as configured by transaction.max.timeout.ms).
CONCURRENT_TRANSACTIONS	51	False	The producer attempted to update a transaction while another concurrent operation on the same transaction was ongoing
TRANSACTION_COORDINATOR_FENCED	52	False	Indicates that the transaction coordinator sending a WriteTxnMarker is no longer the current coordinator for a given producer
TRANSACTIONAL_ID_AUTHORIZATION_FAILED	53	False	Transactional Id authorization failed
SECURITY_DISABLED	54	False	Security features are disabled.
OPERATION_NOT_ATTEMPTED	55	False	The broker did not attempt to execute this operation. This may happen for batched RPCs where some operations in the batch failed, causing the broker to respond without trying the rest.
KAFKA_STORAGE_ERROR	56	True	Disk error when trying to access log file on the disk.
LOG_DIR_NOT_FOUND	57	False	The user-specified log directory is not found in the broker config.
SASL_AUTHENTICATION_FAILED	58	False	SASL Authentication failed.
UNKNOWN_PRODUCER_ID	59	False	This exception is raised by the broker if it could not locate the producer metadata associated with the producerId in question. This could happen if, for instance, the producer's records were deleted because their retention time had elapsed. Once the last records of the producerId are removed, the producer's metadata is removed from the broker, and future appends by the producer will return this exception.
REASSIGNMENT_IN_PROGRESS	60	False	A partition reassignment is in progress
DELEGATION_TOKEN_AUTH_DISABLED	61	False	Delegation Token feature is not enabled.
DELEGATION_TOKEN_NOT_FOUND	62	False	Delegation Token is not found on server.
DELEGATION_TOKEN_OWNER_MISMATCH	63	False	Specified Principal is not valid Owner/Renewer.
DELEGATION_TOKEN_REQUEST_NOT_ALLOWED	64	False	Delegation Token requests are not allowed on PLAINTEXT/1-way SSL channels and on delegation token authenticated channels.
DELEGATION_TOKEN_AUTHORIZATION_FAILED	65	False	Delegation Token authorization failed.
DELEGATION_TOKEN_EXPIRED	66	False	Delegation Token is expired.
INVALID_PRINCIPAL_TYPE	67	False	Supplied principalType is not supported
NON_EMPTY_GROUP	68	False	The group The group is not empty is not empty
GROUP_ID_NOT_FOUND	69	False	The group id The group id does not exist was not found
FETCH_SESSION_ID_NOT_FOUND	70	True	The fetch session ID was not found
INVALID_FETCH_SESSION_EPOCH	71	True	The fetch session epoch is invalid

Api Keys

The following are the numeric codes that the ApiKey in the request can take for each of the below request types.

Name	Key
Produce	0
Fetch	1
ListOffsets	2
Metadata	3
LeaderAndIsr	4
StopReplica	5
UpdateMetadata	6
ControlledShutdown	7
OffsetCommit	8
OffsetFetch	9
FindCoordinator	10
JoinGroup	11
Heartbeat	12
LeaveGroup	13
SyncGroup	14
DescribeGroups	15
ListGroups	16
SaslHandshake	17
ApiVersions	18
CreateTopics	19
DeleteTopics	20
DeleteRecords	21
InitProducerId	22
OffsetForLeaderEpoch	23
AddPartitionsToTxn	24
AddOffsetsToTxn	25
EndTxn	26
WriteTxnMarkers	27
TxnOffsetCommit	28
DescribeAcls	29
CreateAcls	30
DeleteAcls	31
DescribeConfigs	32
AlterConfigs	33
AlterReplicaLogDirs	34
DescribeLogDirs	35
SaslAuthenticate	36
CreatePartitions	37
CreateDelegationToken	38
RenewDelegationToken	39
ExpireDelegationToken	40
DescribeDelegationToken	41
DeleteGroups	42

The Messages

This section gives details on each of the individual API Messages, their usage, their binary format, and the meaning of their fields.

Headers:

Request Header => api_key api_version correlation_id client_id 
  api_key => INT16
  api_version => INT16
  correlation_id => INT32
  client_id => NULLABLE_STRING

Field	Description
api_key	The id of the request type.
api_version	The version of the API.
correlation_id	A user-supplied integer value that will be passed back with the response
client_id	A user specified identifier for the client making the request.

Response Header => correlation_id 
  correlation_id => INT32

Field	Description
correlation_id	The user-supplied value passed in with the request

Produce API (Key: 0):

Requests:

Produce Request (Version: 0) => acks timeout [topic_data] 
  acks => INT16
  timeout => INT32
  topic_data => topic [data] 
    topic => STRING
    data => partition record_set 
      partition => INT32
      record_set => RECORDS

Field	Description
acks	The number of acknowledgments the producer requires the leader to have received before considering a request complete. Allowed values: 0 for no acknowledgments, 1 for only the leader and -1 for the full ISR.
timeout	The time to await a response in ms.
topic_data	null
topic	Name of topic
data	null
partition	Topic partition id
record_set	null

Produce Request (Version: 1) => acks timeout [topic_data] 
  acks => INT16
  timeout => INT32
  topic_data => topic [data] 
    topic => STRING
    data => partition record_set 
      partition => INT32
      record_set => RECORDS

Field	Description
acks	The number of acknowledgments the producer requires the leader to have received before considering a request complete. Allowed values: 0 for no acknowledgments, 1 for only the leader and -1 for the full ISR.
timeout	The time to await a response in ms.
topic_data	null
topic	Name of topic
data	null
partition	Topic partition id
record_set	null

Produce Request (Version: 2) => acks timeout [topic_data] 
  acks => INT16
  timeout => INT32
  topic_data => topic [data] 
    topic => STRING
    data => partition record_set 
      partition => INT32
      record_set => RECORDS

Field	Description
acks	The number of acknowledgments the producer requires the leader to have received before considering a request complete. Allowed values: 0 for no acknowledgments, 1 for only the leader and -1 for the full ISR.
timeout	The time to await a response in ms.
topic_data	null
topic	Name of topic
data	null
partition	Topic partition id
record_set	null

Produce Request (Version: 3) => transactional_id acks timeout [topic_data] 
  transactional_id => NULLABLE_STRING
  acks => INT16
  timeout => INT32
  topic_data => topic [data] 
    topic => STRING
    data => partition record_set 
      partition => INT32
      record_set => RECORDS

Field	Description
transactional_id	The transactional id or null if the producer is not transactional
acks	The number of acknowledgments the producer requires the leader to have received before considering a request complete. Allowed values: 0 for no acknowledgments, 1 for only the leader and -1 for the full ISR.
timeout	The time to await a response in ms.
topic_data	null
topic	Name of topic
data	null
partition	Topic partition id
record_set	null

Produce Request (Version: 4) => transactional_id acks timeout [topic_data] 
  transactional_id => NULLABLE_STRING
  acks => INT16
  timeout => INT32
  topic_data => topic [data] 
    topic => STRING
    data => partition record_set 
      partition => INT32
      record_set => RECORDS

Field	Description
transactional_id	The transactional id or null if the producer is not transactional
acks	The number of acknowledgments the producer requires the leader to have received before considering a request complete. Allowed values: 0 for no acknowledgments, 1 for only the leader and -1 for the full ISR.
timeout	The time to await a response in ms.
topic_data	null
topic	Name of topic
data	null
partition	Topic partition id
record_set	null

Produce Request (Version: 5) => transactional_id acks timeout [topic_data] 
  transactional_id => NULLABLE_STRING
  acks => INT16
  timeout => INT32
  topic_data => topic [data] 
    topic => STRING
    data => partition record_set 
      partition => INT32
      record_set => RECORDS

Field	Description
transactional_id	The transactional id or null if the producer is not transactional
acks	The number of acknowledgments the producer requires the leader to have received before considering a request complete. Allowed values: 0 for no acknowledgments, 1 for only the leader and -1 for the full ISR.
timeout	The time to await a response in ms.
topic_data	null
topic	Name of topic
data	null
partition	Topic partition id
record_set	null

Responses:

Produce Response (Version: 0) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code base_offset 
      partition => INT32
      error_code => INT16
      base_offset => INT64

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
base_offset	null

Produce Response (Version: 1) => [responses] throttle_time_ms 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code base_offset 
      partition => INT32
      error_code => INT16
      base_offset => INT64
  throttle_time_ms => INT32

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
base_offset	null
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

Produce Response (Version: 2) => [responses] throttle_time_ms 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code base_offset log_append_time 
      partition => INT32
      error_code => INT16
      base_offset => INT64
      log_append_time => INT64
  throttle_time_ms => INT32

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
base_offset	null
log_append_time	The timestamp returned by broker after appending the messages. If CreateTime is used for the topic, the timestamp will be -1. If LogAppendTime is used for the topic, the timestamp will be the broker local time when the messages are appended.
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

Produce Response (Version: 3) => [responses] throttle_time_ms 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code base_offset log_append_time 
      partition => INT32
      error_code => INT16
      base_offset => INT64
      log_append_time => INT64
  throttle_time_ms => INT32

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
base_offset	null
log_append_time	The timestamp returned by broker after appending the messages. If CreateTime is used for the topic, the timestamp will be -1. If LogAppendTime is used for the topic, the timestamp will be the broker local time when the messages are appended.
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

Produce Response (Version: 4) => [responses] throttle_time_ms 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code base_offset log_append_time 
      partition => INT32
      error_code => INT16
      base_offset => INT64
      log_append_time => INT64
  throttle_time_ms => INT32

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
base_offset	null
log_append_time	The timestamp returned by broker after appending the messages. If CreateTime is used for the topic, the timestamp will be -1. If LogAppendTime is used for the topic, the timestamp will be the broker local time when the messages are appended.
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

Produce Response (Version: 5) => [responses] throttle_time_ms 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code base_offset log_append_time log_start_offset 
      partition => INT32
      error_code => INT16
      base_offset => INT64
      log_append_time => INT64
      log_start_offset => INT64
  throttle_time_ms => INT32

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
base_offset	null
log_append_time	The timestamp returned by broker after appending the messages. If CreateTime is used for the topic, the timestamp will be -1. If LogAppendTime is used for the topic, the timestamp will be the broker local time when the messages are appended.
log_start_offset	The start offset of the log at the time this produce response was created
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

Fetch API (Key: 1):

Requests:

Fetch Request (Version: 0) => replica_id max_wait_time min_bytes [topics] 
  replica_id => INT32
  max_wait_time => INT32
  min_bytes => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition fetch_offset max_bytes 
      partition => INT32
      fetch_offset => INT64
      max_bytes => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
max_wait_time	Maximum time in ms to wait for the response.
min_bytes	Minimum bytes to accumulate in the response.
topics	Topics to fetch.
topic	Name of topic
partitions	Partitions to fetch.
partition	Topic partition id
fetch_offset	Message offset.
max_bytes	Maximum bytes to fetch.

Fetch Request (Version: 1) => replica_id max_wait_time min_bytes [topics] 
  replica_id => INT32
  max_wait_time => INT32
  min_bytes => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition fetch_offset max_bytes 
      partition => INT32
      fetch_offset => INT64
      max_bytes => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
max_wait_time	Maximum time in ms to wait for the response.
min_bytes	Minimum bytes to accumulate in the response.
topics	Topics to fetch.
topic	Name of topic
partitions	Partitions to fetch.
partition	Topic partition id
fetch_offset	Message offset.
max_bytes	Maximum bytes to fetch.

Fetch Request (Version: 2) => replica_id max_wait_time min_bytes [topics] 
  replica_id => INT32
  max_wait_time => INT32
  min_bytes => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition fetch_offset max_bytes 
      partition => INT32
      fetch_offset => INT64
      max_bytes => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
max_wait_time	Maximum time in ms to wait for the response.
min_bytes	Minimum bytes to accumulate in the response.
topics	Topics to fetch.
topic	Name of topic
partitions	Partitions to fetch.
partition	Topic partition id
fetch_offset	Message offset.
max_bytes	Maximum bytes to fetch.

Fetch Request (Version: 3) => replica_id max_wait_time min_bytes max_bytes [topics] 
  replica_id => INT32
  max_wait_time => INT32
  min_bytes => INT32
  max_bytes => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition fetch_offset max_bytes 
      partition => INT32
      fetch_offset => INT64
      max_bytes => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
max_wait_time	Maximum time in ms to wait for the response.
min_bytes	Minimum bytes to accumulate in the response.
max_bytes	Maximum bytes to accumulate in the response. Note that this is not an absolute maximum, if the first message in the first non-empty partition of the fetch is larger than this value, the message will still be returned to ensure that progress can be made.
topics	Topics to fetch in the order provided.
topic	Name of topic
partitions	Partitions to fetch.
partition	Topic partition id
fetch_offset	Message offset.
max_bytes	Maximum bytes to fetch.

Fetch Request (Version: 4) => replica_id max_wait_time min_bytes max_bytes isolation_level [topics] 
  replica_id => INT32
  max_wait_time => INT32
  min_bytes => INT32
  max_bytes => INT32
  isolation_level => INT8
  topics => topic [partitions] 
    topic => STRING
    partitions => partition fetch_offset max_bytes 
      partition => INT32
      fetch_offset => INT64
      max_bytes => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
max_wait_time	Maximum time in ms to wait for the response.
min_bytes	Minimum bytes to accumulate in the response.
max_bytes	Maximum bytes to accumulate in the response. Note that this is not an absolute maximum, if the first message in the first non-empty partition of the fetch is larger than this value, the message will still be returned to ensure that progress can be made.
isolation_level	This setting controls the visibility of transactional records. Using READ_UNCOMMITTED (isolation_level = 0) makes all records visible. With READ_COMMITTED (isolation_level = 1), non-transactional and COMMITTED transactional records are visible. To be more concrete, READ_COMMITTED returns all data from offsets smaller than the current LSO (last stable offset), and enables the inclusion of the list of aborted transactions in the result, which allows consumers to discard ABORTED transactional records
topics	Topics to fetch in the order provided.
topic	Name of topic
partitions	Partitions to fetch.
partition	Topic partition id
fetch_offset	Message offset.
max_bytes	Maximum bytes to fetch.

Fetch Request (Version: 5) => replica_id max_wait_time min_bytes max_bytes isolation_level [topics] 
  replica_id => INT32
  max_wait_time => INT32
  min_bytes => INT32
  max_bytes => INT32
  isolation_level => INT8
  topics => topic [partitions] 
    topic => STRING
    partitions => partition fetch_offset log_start_offset max_bytes 
      partition => INT32
      fetch_offset => INT64
      log_start_offset => INT64
      max_bytes => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
max_wait_time	Maximum time in ms to wait for the response.
min_bytes	Minimum bytes to accumulate in the response.
max_bytes	Maximum bytes to accumulate in the response. Note that this is not an absolute maximum, if the first message in the first non-empty partition of the fetch is larger than this value, the message will still be returned to ensure that progress can be made.
isolation_level	This setting controls the visibility of transactional records. Using READ_UNCOMMITTED (isolation_level = 0) makes all records visible. With READ_COMMITTED (isolation_level = 1), non-transactional and COMMITTED transactional records are visible. To be more concrete, READ_COMMITTED returns all data from offsets smaller than the current LSO (last stable offset), and enables the inclusion of the list of aborted transactions in the result, which allows consumers to discard ABORTED transactional records
topics	Topics to fetch in the order provided.
topic	Name of topic
partitions	Partitions to fetch.
partition	Topic partition id
fetch_offset	Message offset.
log_start_offset	Earliest available offset of the follower replica. The field is only used when request is sent by follower.
max_bytes	Maximum bytes to fetch.

Fetch Request (Version: 6) => replica_id max_wait_time min_bytes max_bytes isolation_level [topics] 
  replica_id => INT32
  max_wait_time => INT32
  min_bytes => INT32
  max_bytes => INT32
  isolation_level => INT8
  topics => topic [partitions] 
    topic => STRING
    partitions => partition fetch_offset log_start_offset max_bytes 
      partition => INT32
      fetch_offset => INT64
      log_start_offset => INT64
      max_bytes => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
max_wait_time	Maximum time in ms to wait for the response.
min_bytes	Minimum bytes to accumulate in the response.
max_bytes	Maximum bytes to accumulate in the response. Note that this is not an absolute maximum, if the first message in the first non-empty partition of the fetch is larger than this value, the message will still be returned to ensure that progress can be made.
isolation_level	This setting controls the visibility of transactional records. Using READ_UNCOMMITTED (isolation_level = 0) makes all records visible. With READ_COMMITTED (isolation_level = 1), non-transactional and COMMITTED transactional records are visible. To be more concrete, READ_COMMITTED returns all data from offsets smaller than the current LSO (last stable offset), and enables the inclusion of the list of aborted transactions in the result, which allows consumers to discard ABORTED transactional records
topics	Topics to fetch in the order provided.
topic	Name of topic
partitions	Partitions to fetch.
partition	Topic partition id
fetch_offset	Message offset.
log_start_offset	Earliest available offset of the follower replica. The field is only used when request is sent by follower.
max_bytes	Maximum bytes to fetch.

Fetch Request (Version: 7) => replica_id max_wait_time min_bytes max_bytes isolation_level session_id epoch [topics] [forgetten_topics_data] 
  replica_id => INT32
  max_wait_time => INT32
  min_bytes => INT32
  max_bytes => INT32
  isolation_level => INT8
  session_id => INT32
  epoch => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition fetch_offset log_start_offset max_bytes 
      partition => INT32
      fetch_offset => INT64
      log_start_offset => INT64
      max_bytes => INT32
  forgetten_topics_data => topic [partitions] 
    topic => STRING
    partitions => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
max_wait_time	Maximum time in ms to wait for the response.
min_bytes	Minimum bytes to accumulate in the response.
max_bytes	Maximum bytes to accumulate in the response. Note that this is not an absolute maximum, if the first message in the first non-empty partition of the fetch is larger than this value, the message will still be returned to ensure that progress can be made.
isolation_level	This setting controls the visibility of transactional records. Using READ_UNCOMMITTED (isolation_level = 0) makes all records visible. With READ_COMMITTED (isolation_level = 1), non-transactional and COMMITTED transactional records are visible. To be more concrete, READ_COMMITTED returns all data from offsets smaller than the current LSO (last stable offset), and enables the inclusion of the list of aborted transactions in the result, which allows consumers to discard ABORTED transactional records
session_id	The fetch session ID
epoch	The fetch epoch
topics	Topics to fetch in the order provided.
topic	Name of topic
partitions	Partitions to fetch.
partition	Topic partition id
fetch_offset	Message offset.
log_start_offset	Earliest available offset of the follower replica. The field is only used when request is sent by follower.
max_bytes	Maximum bytes to fetch.
forgetten_topics_data	Topics to remove from the fetch session.
topic	Name of topic
partitions	Partitions to remove from the fetch session.

Responses:

Fetch Response (Version: 0) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition_header record_set 
      partition_header => partition error_code high_watermark 
        partition => INT32
        error_code => INT16
        high_watermark => INT64
      record_set => RECORDS

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition_header	null
partition	Topic partition id
error_code	Response error code
high_watermark	Last committed offset.
record_set	null

Fetch Response (Version: 1) => throttle_time_ms [responses] 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition_header record_set 
      partition_header => partition error_code high_watermark 
        partition => INT32
        error_code => INT16
        high_watermark => INT64
      record_set => RECORDS

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition_header	null
partition	Topic partition id
error_code	Response error code
high_watermark	Last committed offset.
record_set	null

Fetch Response (Version: 2) => throttle_time_ms [responses] 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition_header record_set 
      partition_header => partition error_code high_watermark 
        partition => INT32
        error_code => INT16
        high_watermark => INT64
      record_set => RECORDS

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition_header	null
partition	Topic partition id
error_code	Response error code
high_watermark	Last committed offset.
record_set	null

Fetch Response (Version: 3) => throttle_time_ms [responses] 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition_header record_set 
      partition_header => partition error_code high_watermark 
        partition => INT32
        error_code => INT16
        high_watermark => INT64
      record_set => RECORDS

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition_header	null
partition	Topic partition id
error_code	Response error code
high_watermark	Last committed offset.
record_set	null

Fetch Response (Version: 4) => throttle_time_ms [responses] 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition_header record_set 
      partition_header => partition error_code high_watermark last_stable_offset [aborted_transactions] 
        partition => INT32
        error_code => INT16
        high_watermark => INT64
        last_stable_offset => INT64
        aborted_transactions => producer_id first_offset 
          producer_id => INT64
          first_offset => INT64
      record_set => RECORDS

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition_header	null
partition	Topic partition id
error_code	Response error code
high_watermark	Last committed offset.
last_stable_offset	The last stable offset (or LSO) of the partition. This is the last offset such that the state of all transactional records prior to this offset have been decided (ABORTED or COMMITTED)
aborted_transactions	null
producer_id	The producer id associated with the aborted transactions
first_offset	The first offset in the aborted transaction
record_set	null

Fetch Response (Version: 5) => throttle_time_ms [responses] 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition_header record_set 
      partition_header => partition error_code high_watermark last_stable_offset log_start_offset [aborted_transactions] 
        partition => INT32
        error_code => INT16
        high_watermark => INT64
        last_stable_offset => INT64
        log_start_offset => INT64
        aborted_transactions => producer_id first_offset 
          producer_id => INT64
          first_offset => INT64
      record_set => RECORDS

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition_header	null
partition	Topic partition id
error_code	Response error code
high_watermark	Last committed offset.
last_stable_offset	The last stable offset (or LSO) of the partition. This is the last offset such that the state of all transactional records prior to this offset have been decided (ABORTED or COMMITTED)
log_start_offset	Earliest available offset.
aborted_transactions	null
producer_id	The producer id associated with the aborted transactions
first_offset	The first offset in the aborted transaction
record_set	null

Fetch Response (Version: 6) => throttle_time_ms [responses] 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition_header record_set 
      partition_header => partition error_code high_watermark last_stable_offset log_start_offset [aborted_transactions] 
        partition => INT32
        error_code => INT16
        high_watermark => INT64
        last_stable_offset => INT64
        log_start_offset => INT64
        aborted_transactions => producer_id first_offset 
          producer_id => INT64
          first_offset => INT64
      record_set => RECORDS

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition_header	null
partition	Topic partition id
error_code	Response error code
high_watermark	Last committed offset.
last_stable_offset	The last stable offset (or LSO) of the partition. This is the last offset such that the state of all transactional records prior to this offset have been decided (ABORTED or COMMITTED)
log_start_offset	Earliest available offset.
aborted_transactions	null
producer_id	The producer id associated with the aborted transactions
first_offset	The first offset in the aborted transaction
record_set	null

Fetch Response (Version: 7) => throttle_time_ms error_code session_id [responses] 
  throttle_time_ms => INT32
  error_code => INT16
  session_id => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition_header record_set 
      partition_header => partition error_code high_watermark last_stable_offset log_start_offset [aborted_transactions] 
        partition => INT32
        error_code => INT16
        high_watermark => INT64
        last_stable_offset => INT64
        log_start_offset => INT64
        aborted_transactions => producer_id first_offset 
          producer_id => INT64
          first_offset => INT64
      record_set => RECORDS

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code
session_id	The fetch session ID
responses	null
topic	Name of topic
partition_responses	null
partition_header	null
partition	Topic partition id
error_code	Response error code
high_watermark	Last committed offset.
last_stable_offset	The last stable offset (or LSO) of the partition. This is the last offset such that the state of all transactional records prior to this offset have been decided (ABORTED or COMMITTED)
log_start_offset	Earliest available offset.
aborted_transactions	null
producer_id	The producer id associated with the aborted transactions
first_offset	The first offset in the aborted transaction
record_set	null

ListOffsets API (Key: 2):

Requests:

ListOffsets Request (Version: 0) => replica_id [topics] 
  replica_id => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition timestamp max_num_offsets 
      partition => INT32
      timestamp => INT64
      max_num_offsets => INT32

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
topics	Topics to list offsets.
topic	Name of topic
partitions	Partitions to list offset.
partition	Topic partition id
timestamp	Timestamp.
max_num_offsets	Maximum offsets to return.

ListOffsets Request (Version: 1) => replica_id [topics] 
  replica_id => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition timestamp 
      partition => INT32
      timestamp => INT64

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
topics	Topics to list offsets.
topic	Name of topic
partitions	Partitions to list offset.
partition	Topic partition id
timestamp	The target timestamp for the partition.

ListOffsets Request (Version: 2) => replica_id isolation_level [topics] 
  replica_id => INT32
  isolation_level => INT8
  topics => topic [partitions] 
    topic => STRING
    partitions => partition timestamp 
      partition => INT32
      timestamp => INT64

Field	Description
replica_id	Broker id of the follower. For normal consumers, use -1.
isolation_level	This setting controls the visibility of transactional records. Using READ_UNCOMMITTED (isolation_level = 0) makes all records visible. With READ_COMMITTED (isolation_level = 1), non-transactional and COMMITTED transactional records are visible. To be more concrete, READ_COMMITTED returns all data from offsets smaller than the current LSO (last stable offset), and enables the inclusion of the list of aborted transactions in the result, which allows consumers to discard ABORTED transactional records
topics	Topics to list offsets.
topic	Name of topic
partitions	Partitions to list offset.
partition	Topic partition id
timestamp	The target timestamp for the partition.

Responses:

ListOffsets Response (Version: 0) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code [offsets] 
      partition => INT32
      error_code => INT16
      offsets => INT64

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
offsets	A list of offsets.

ListOffsets Response (Version: 1) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code timestamp offset 
      partition => INT32
      error_code => INT16
      timestamp => INT64
      offset => INT64

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
timestamp	The timestamp associated with the returned offset
offset	offset found

ListOffsets Response (Version: 2) => throttle_time_ms [responses] 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code timestamp offset 
      partition => INT32
      error_code => INT16
      timestamp => INT64
      offset => INT64

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code
timestamp	The timestamp associated with the returned offset
offset	offset found

Metadata API (Key: 3):

Requests:

Metadata Request (Version: 0) => [topics] 
  topics => STRING

Field	Description
topics	An array of topics to fetch metadata for. If no topics are specified fetch metadata for all topics.

Metadata Request (Version: 1) => [topics] 
  topics => STRING

Field	Description
topics	An array of topics to fetch metadata for. If the topics array is null fetch metadata for all topics.

Metadata Request (Version: 2) => [topics] 
  topics => STRING

Field	Description
topics	An array of topics to fetch metadata for. If the topics array is null fetch metadata for all topics.

Metadata Request (Version: 3) => [topics] 
  topics => STRING

Field	Description
topics	An array of topics to fetch metadata for. If the topics array is null fetch metadata for all topics.

Metadata Request (Version: 4) => [topics] allow_auto_topic_creation 
  topics => STRING
  allow_auto_topic_creation => BOOLEAN

Field	Description
topics	An array of topics to fetch metadata for. If the topics array is null fetch metadata for all topics.
allow_auto_topic_creation	If this and the broker config 'auto.create.topics.enable' are true, topics that don't exist will be created by the broker. Otherwise, no topics will be created by the broker.

Metadata Request (Version: 5) => [topics] allow_auto_topic_creation 
  topics => STRING
  allow_auto_topic_creation => BOOLEAN

Field	Description
topics	An array of topics to fetch metadata for. If the topics array is null fetch metadata for all topics.
allow_auto_topic_creation	If this and the broker config 'auto.create.topics.enable' are true, topics that don't exist will be created by the broker. Otherwise, no topics will be created by the broker.

Responses:

Metadata Response (Version: 0) => [brokers] [topic_metadata] 
  brokers => node_id host port 
    node_id => INT32
    host => STRING
    port => INT32
  topic_metadata => error_code topic [partition_metadata] 
    error_code => INT16
    topic => STRING
    partition_metadata => error_code partition leader [replicas] [isr] 
      error_code => INT16
      partition => INT32
      leader => INT32
      replicas => INT32
      isr => INT32

Field	Description
brokers	Host and port information for all brokers.
node_id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.
topic_metadata	null
error_code	Response error code
topic	Name of topic
partition_metadata	Metadata for each partition of the topic.
error_code	Response error code
partition	Topic partition id
leader	The id of the broker acting as leader for this partition.
replicas	The set of all nodes that host this partition.
isr	The set of nodes that are in sync with the leader for this partition.

Metadata Response (Version: 1) => [brokers] controller_id [topic_metadata] 
  brokers => node_id host port rack 
    node_id => INT32
    host => STRING
    port => INT32
    rack => NULLABLE_STRING
  controller_id => INT32
  topic_metadata => error_code topic is_internal [partition_metadata] 
    error_code => INT16
    topic => STRING
    is_internal => BOOLEAN
    partition_metadata => error_code partition leader [replicas] [isr] 
      error_code => INT16
      partition => INT32
      leader => INT32
      replicas => INT32
      isr => INT32

Field	Description
brokers	Host and port information for all brokers.
node_id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.
rack	The rack of the broker.
controller_id	The broker id of the controller broker.
topic_metadata	null
error_code	Response error code
topic	Name of topic
is_internal	Indicates if the topic is considered a Kafka internal topic
partition_metadata	Metadata for each partition of the topic.
error_code	Response error code
partition	Topic partition id
leader	The id of the broker acting as leader for this partition.
replicas	The set of all nodes that host this partition.
isr	The set of nodes that are in sync with the leader for this partition.

Metadata Response (Version: 2) => [brokers] cluster_id controller_id [topic_metadata] 
  brokers => node_id host port rack 
    node_id => INT32
    host => STRING
    port => INT32
    rack => NULLABLE_STRING
  cluster_id => NULLABLE_STRING
  controller_id => INT32
  topic_metadata => error_code topic is_internal [partition_metadata] 
    error_code => INT16
    topic => STRING
    is_internal => BOOLEAN
    partition_metadata => error_code partition leader [replicas] [isr] 
      error_code => INT16
      partition => INT32
      leader => INT32
      replicas => INT32
      isr => INT32

Field	Description
brokers	Host and port information for all brokers.
node_id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.
rack	The rack of the broker.
cluster_id	The cluster id that this broker belongs to.
controller_id	The broker id of the controller broker.
topic_metadata	null
error_code	Response error code
topic	Name of topic
is_internal	Indicates if the topic is considered a Kafka internal topic
partition_metadata	Metadata for each partition of the topic.
error_code	Response error code
partition	Topic partition id
leader	The id of the broker acting as leader for this partition.
replicas	The set of all nodes that host this partition.
isr	The set of nodes that are in sync with the leader for this partition.

Metadata Response (Version: 3) => throttle_time_ms [brokers] cluster_id controller_id [topic_metadata] 
  throttle_time_ms => INT32
  brokers => node_id host port rack 
    node_id => INT32
    host => STRING
    port => INT32
    rack => NULLABLE_STRING
  cluster_id => NULLABLE_STRING
  controller_id => INT32
  topic_metadata => error_code topic is_internal [partition_metadata] 
    error_code => INT16
    topic => STRING
    is_internal => BOOLEAN
    partition_metadata => error_code partition leader [replicas] [isr] 
      error_code => INT16
      partition => INT32
      leader => INT32
      replicas => INT32
      isr => INT32

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
brokers	Host and port information for all brokers.
node_id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.
rack	The rack of the broker.
cluster_id	The cluster id that this broker belongs to.
controller_id	The broker id of the controller broker.
topic_metadata	null
error_code	Response error code
topic	Name of topic
is_internal	Indicates if the topic is considered a Kafka internal topic
partition_metadata	Metadata for each partition of the topic.
error_code	Response error code
partition	Topic partition id
leader	The id of the broker acting as leader for this partition.
replicas	The set of all nodes that host this partition.
isr	The set of nodes that are in sync with the leader for this partition.

Metadata Response (Version: 4) => throttle_time_ms [brokers] cluster_id controller_id [topic_metadata] 
  throttle_time_ms => INT32
  brokers => node_id host port rack 
    node_id => INT32
    host => STRING
    port => INT32
    rack => NULLABLE_STRING
  cluster_id => NULLABLE_STRING
  controller_id => INT32
  topic_metadata => error_code topic is_internal [partition_metadata] 
    error_code => INT16
    topic => STRING
    is_internal => BOOLEAN
    partition_metadata => error_code partition leader [replicas] [isr] 
      error_code => INT16
      partition => INT32
      leader => INT32
      replicas => INT32
      isr => INT32

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
brokers	Host and port information for all brokers.
node_id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.
rack	The rack of the broker.
cluster_id	The cluster id that this broker belongs to.
controller_id	The broker id of the controller broker.
topic_metadata	null
error_code	Response error code
topic	Name of topic
is_internal	Indicates if the topic is considered a Kafka internal topic
partition_metadata	Metadata for each partition of the topic.
error_code	Response error code
partition	Topic partition id
leader	The id of the broker acting as leader for this partition.
replicas	The set of all nodes that host this partition.
isr	The set of nodes that are in sync with the leader for this partition.

Metadata Response (Version: 5) => throttle_time_ms [brokers] cluster_id controller_id [topic_metadata] 
  throttle_time_ms => INT32
  brokers => node_id host port rack 
    node_id => INT32
    host => STRING
    port => INT32
    rack => NULLABLE_STRING
  cluster_id => NULLABLE_STRING
  controller_id => INT32
  topic_metadata => error_code topic is_internal [partition_metadata] 
    error_code => INT16
    topic => STRING
    is_internal => BOOLEAN
    partition_metadata => error_code partition leader [replicas] [isr] [offline_replicas] 
      error_code => INT16
      partition => INT32
      leader => INT32
      replicas => INT32
      isr => INT32
      offline_replicas => INT32

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
brokers	Host and port information for all brokers.
node_id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.
rack	The rack of the broker.
cluster_id	The cluster id that this broker belongs to.
controller_id	The broker id of the controller broker.
topic_metadata	null
error_code	Response error code
topic	Name of topic
is_internal	Indicates if the topic is considered a Kafka internal topic
partition_metadata	Metadata for each partition of the topic.
error_code	Response error code
partition	Topic partition id
leader	The id of the broker acting as leader for this partition.
replicas	The set of all nodes that host this partition.
isr	The set of nodes that are in sync with the leader for this partition.
offline_replicas	The set of offline replicas of this partition.

LeaderAndIsr API (Key: 4):

Requests:

LeaderAndIsr Request (Version: 0) => controller_id controller_epoch [partition_states] [live_leaders] 
  controller_id => INT32
  controller_epoch => INT32
  partition_states => topic partition controller_epoch leader leader_epoch [isr] zk_version [replicas] 
    topic => STRING
    partition => INT32
    controller_epoch => INT32
    leader => INT32
    leader_epoch => INT32
    isr => INT32
    zk_version => INT32
    replicas => INT32
  live_leaders => id host port 
    id => INT32
    host => STRING
    port => INT32

Field	Description
controller_id	The controller id.
controller_epoch	The controller epoch.
partition_states	null
topic	Name of topic
partition	Topic partition id
controller_epoch	The controller epoch.
leader	The broker id for the leader.
leader_epoch	The leader epoch.
isr	The in sync replica ids.
zk_version	The ZK version.
replicas	The replica ids.
live_leaders	null
id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.

LeaderAndIsr Request (Version: 1) => controller_id controller_epoch [partition_states] [live_leaders] 
  controller_id => INT32
  controller_epoch => INT32
  partition_states => topic partition controller_epoch leader leader_epoch [isr] zk_version [replicas] is_new 
    topic => STRING
    partition => INT32
    controller_epoch => INT32
    leader => INT32
    leader_epoch => INT32
    isr => INT32
    zk_version => INT32
    replicas => INT32
    is_new => BOOLEAN
  live_leaders => id host port 
    id => INT32
    host => STRING
    port => INT32

Field	Description
controller_id	The controller id.
controller_epoch	The controller epoch.
partition_states	null
topic	Name of topic
partition	Topic partition id
controller_epoch	The controller epoch.
leader	The broker id for the leader.
leader_epoch	The leader epoch.
isr	The in sync replica ids.
zk_version	The ZK version.
replicas	The replica ids.
is_new	Whether the replica should have existed on the broker or not
live_leaders	null
id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.

Responses:

LeaderAndIsr Response (Version: 0) => error_code [partitions] 
  error_code => INT16
  partitions => topic partition error_code 
    topic => STRING
    partition => INT32
    error_code => INT16

Field	Description
error_code	Response error code
partitions	null
topic	Name of topic
partition	Topic partition id
error_code	Response error code

LeaderAndIsr Response (Version: 1) => error_code [partitions] 
  error_code => INT16
  partitions => topic partition error_code 
    topic => STRING
    partition => INT32
    error_code => INT16

Field	Description
error_code	Response error code
partitions	null
topic	Name of topic
partition	Topic partition id
error_code	Response error code

StopReplica API (Key: 5):

Requests:

StopReplica Request (Version: 0) => controller_id controller_epoch delete_partitions [partitions] 
  controller_id => INT32
  controller_epoch => INT32
  delete_partitions => BOOLEAN
  partitions => topic partition 
    topic => STRING
    partition => INT32

Field	Description
controller_id	The controller id.
controller_epoch	The controller epoch.
delete_partitions	Boolean which indicates if replica's partitions must be deleted.
partitions	null
topic	Name of topic
partition	Topic partition id

Responses:

StopReplica Response (Version: 0) => error_code [partitions] 
  error_code => INT16
  partitions => topic partition error_code 
    topic => STRING
    partition => INT32
    error_code => INT16

Field	Description
error_code	Response error code
partitions	null
topic	Name of topic
partition	Topic partition id
error_code	Response error code

UpdateMetadata API (Key: 6):

Requests:

UpdateMetadata Request (Version: 0) => controller_id controller_epoch [partition_states] [live_brokers] 
  controller_id => INT32
  controller_epoch => INT32
  partition_states => topic partition controller_epoch leader leader_epoch [isr] zk_version [replicas] 
    topic => STRING
    partition => INT32
    controller_epoch => INT32
    leader => INT32
    leader_epoch => INT32
    isr => INT32
    zk_version => INT32
    replicas => INT32
  live_brokers => id host port 
    id => INT32
    host => STRING
    port => INT32

Field	Description
controller_id	The controller id.
controller_epoch	The controller epoch.
partition_states	null
topic	Name of topic
partition	Topic partition id
controller_epoch	The controller epoch.
leader	The broker id for the leader.
leader_epoch	The leader epoch.
isr	The in sync replica ids.
zk_version	The ZK version.
replicas	The replica ids.
live_brokers	null
id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.

UpdateMetadata Request (Version: 1) => controller_id controller_epoch [partition_states] [live_brokers] 
  controller_id => INT32
  controller_epoch => INT32
  partition_states => topic partition controller_epoch leader leader_epoch [isr] zk_version [replicas] 
    topic => STRING
    partition => INT32
    controller_epoch => INT32
    leader => INT32
    leader_epoch => INT32
    isr => INT32
    zk_version => INT32
    replicas => INT32
  live_brokers => id [end_points] 
    id => INT32
    end_points => port host security_protocol_type 
      port => INT32
      host => STRING
      security_protocol_type => INT16

Field	Description
controller_id	The controller id.
controller_epoch	The controller epoch.
partition_states	null
topic	Name of topic
partition	Topic partition id
controller_epoch	The controller epoch.
leader	The broker id for the leader.
leader_epoch	The leader epoch.
isr	The in sync replica ids.
zk_version	The ZK version.
replicas	The replica ids.
live_brokers	null
id	The broker id.
end_points	null
port	The port on which the broker accepts requests.
host	The hostname of the broker.
security_protocol_type	The security protocol type.

UpdateMetadata Request (Version: 2) => controller_id controller_epoch [partition_states] [live_brokers] 
  controller_id => INT32
  controller_epoch => INT32
  partition_states => topic partition controller_epoch leader leader_epoch [isr] zk_version [replicas] 
    topic => STRING
    partition => INT32
    controller_epoch => INT32
    leader => INT32
    leader_epoch => INT32
    isr => INT32
    zk_version => INT32
    replicas => INT32
  live_brokers => id [end_points] rack 
    id => INT32
    end_points => port host security_protocol_type 
      port => INT32
      host => STRING
      security_protocol_type => INT16
    rack => NULLABLE_STRING

Field	Description
controller_id	The controller id.
controller_epoch	The controller epoch.
partition_states	null
topic	Name of topic
partition	Topic partition id
controller_epoch	The controller epoch.
leader	The broker id for the leader.
leader_epoch	The leader epoch.
isr	The in sync replica ids.
zk_version	The ZK version.
replicas	The replica ids.
live_brokers	null
id	The broker id.
end_points	null
port	The port on which the broker accepts requests.
host	The hostname of the broker.
security_protocol_type	The security protocol type.
rack	The rack

UpdateMetadata Request (Version: 3) => controller_id controller_epoch [partition_states] [live_brokers] 
  controller_id => INT32
  controller_epoch => INT32
  partition_states => topic partition controller_epoch leader leader_epoch [isr] zk_version [replicas] 
    topic => STRING
    partition => INT32
    controller_epoch => INT32
    leader => INT32
    leader_epoch => INT32
    isr => INT32
    zk_version => INT32
    replicas => INT32
  live_brokers => id [end_points] rack 
    id => INT32
    end_points => port host listener_name security_protocol_type 
      port => INT32
      host => STRING
      listener_name => STRING
      security_protocol_type => INT16
    rack => NULLABLE_STRING

Field	Description
controller_id	The controller id.
controller_epoch	The controller epoch.
partition_states	null
topic	Name of topic
partition	Topic partition id
controller_epoch	The controller epoch.
leader	The broker id for the leader.
leader_epoch	The leader epoch.
isr	The in sync replica ids.
zk_version	The ZK version.
replicas	The replica ids.
live_brokers	null
id	The broker id.
end_points	null
port	The port on which the broker accepts requests.
host	The hostname of the broker.
listener_name	The listener name.
security_protocol_type	The security protocol type.
rack	The rack

UpdateMetadata Request (Version: 4) => controller_id controller_epoch [partition_states] [live_brokers] 
  controller_id => INT32
  controller_epoch => INT32
  partition_states => topic partition controller_epoch leader leader_epoch [isr] zk_version [replicas] [offline_replicas] 
    topic => STRING
    partition => INT32
    controller_epoch => INT32
    leader => INT32
    leader_epoch => INT32
    isr => INT32
    zk_version => INT32
    replicas => INT32
    offline_replicas => INT32
  live_brokers => id [end_points] rack 
    id => INT32
    end_points => port host listener_name security_protocol_type 
      port => INT32
      host => STRING
      listener_name => STRING
      security_protocol_type => INT16
    rack => NULLABLE_STRING

Field	Description
controller_id	The controller id.
controller_epoch	The controller epoch.
partition_states	null
topic	Name of topic
partition	Topic partition id
controller_epoch	The controller epoch.
leader	The broker id for the leader.
leader_epoch	The leader epoch.
isr	The in sync replica ids.
zk_version	The ZK version.
replicas	The replica ids.
offline_replicas	The offline replica ids
live_brokers	null
id	The broker id.
end_points	null
port	The port on which the broker accepts requests.
host	The hostname of the broker.
listener_name	The listener name.
security_protocol_type	The security protocol type.
rack	The rack

Responses:

UpdateMetadata Response (Version: 0) => error_code 
  error_code => INT16

Field	Description
error_code	Response error code

UpdateMetadata Response (Version: 1) => error_code 
  error_code => INT16

Field	Description
error_code	Response error code

UpdateMetadata Response (Version: 2) => error_code 
  error_code => INT16

Field	Description
error_code	Response error code

UpdateMetadata Response (Version: 3) => error_code 
  error_code => INT16

Field	Description
error_code	Response error code

UpdateMetadata Response (Version: 4) => error_code 
  error_code => INT16

Field	Description
error_code	Response error code

ControlledShutdown API (Key: 7):

Requests:

ControlledShutdown Request (Version: 0) => broker_id 
  broker_id => INT32

Field	Description
broker_id	The id of the broker for which controlled shutdown has been requested.

ControlledShutdown Request (Version: 1) => broker_id 
  broker_id => INT32

Field	Description
broker_id	The id of the broker for which controlled shutdown has been requested.

Responses:

ControlledShutdown Response (Version: 0) => error_code [partitions_remaining] 
  error_code => INT16
  partitions_remaining => topic partition 
    topic => STRING
    partition => INT32

Field	Description
error_code	Response error code
partitions_remaining	The partitions that the broker still leads.
topic	Name of topic
partition	Topic partition id

ControlledShutdown Response (Version: 1) => error_code [partitions_remaining] 
  error_code => INT16
  partitions_remaining => topic partition 
    topic => STRING
    partition => INT32

Field	Description
error_code	Response error code
partitions_remaining	The partitions that the broker still leads.
topic	Name of topic
partition	Topic partition id

OffsetCommit API (Key: 8):

Requests:

OffsetCommit Request (Version: 0) => group_id [topics] 
  group_id => STRING
  topics => topic [partitions] 
    topic => STRING
    partitions => partition offset metadata 
      partition => INT32
      offset => INT64
      metadata => NULLABLE_STRING

Field	Description
group_id	The unique group identifier
topics	Topics to commit offsets.
topic	Name of topic
partitions	Partitions to commit offsets.
partition	Topic partition id
offset	Message offset to be committed.
metadata	Any associated metadata the client wants to keep.

OffsetCommit Request (Version: 1) => group_id generation_id member_id [topics] 
  group_id => STRING
  generation_id => INT32
  member_id => STRING
  topics => topic [partitions] 
    topic => STRING
    partitions => partition offset timestamp metadata 
      partition => INT32
      offset => INT64
      timestamp => INT64
      metadata => NULLABLE_STRING

Field	Description
group_id	The unique group identifier
generation_id	The generation of the group.
member_id	The member id assigned by the group coordinator or null if joining for the first time.
topics	Topics to commit offsets.
topic	Name of topic
partitions	Partitions to commit offsets.
partition	Topic partition id
offset	Message offset to be committed.
timestamp	Timestamp of the commit
metadata	Any associated metadata the client wants to keep.

OffsetCommit Request (Version: 2) => group_id generation_id member_id retention_time [topics] 
  group_id => STRING
  generation_id => INT32
  member_id => STRING
  retention_time => INT64
  topics => topic [partitions] 
    topic => STRING
    partitions => partition offset metadata 
      partition => INT32
      offset => INT64
      metadata => NULLABLE_STRING

Field	Description
group_id	The unique group identifier
generation_id	The generation of the group.
member_id	The member id assigned by the group coordinator or null if joining for the first time.
retention_time	Time period in ms to retain the offset.
topics	Topics to commit offsets.
topic	Name of topic
partitions	Partitions to commit offsets.
partition	Topic partition id
offset	Message offset to be committed.
metadata	Any associated metadata the client wants to keep.

OffsetCommit Request (Version: 3) => group_id generation_id member_id retention_time [topics] 
  group_id => STRING
  generation_id => INT32
  member_id => STRING
  retention_time => INT64
  topics => topic [partitions] 
    topic => STRING
    partitions => partition offset metadata 
      partition => INT32
      offset => INT64
      metadata => NULLABLE_STRING

Field	Description
group_id	The unique group identifier
generation_id	The generation of the group.
member_id	The member id assigned by the group coordinator or null if joining for the first time.
retention_time	Time period in ms to retain the offset.
topics	Topics to commit offsets.
topic	Name of topic
partitions	Partitions to commit offsets.
partition	Topic partition id
offset	Message offset to be committed.
metadata	Any associated metadata the client wants to keep.

Responses:

OffsetCommit Response (Version: 0) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code 
      partition => INT32
      error_code => INT16

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code

OffsetCommit Response (Version: 1) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code 
      partition => INT32
      error_code => INT16

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code

OffsetCommit Response (Version: 2) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code 
      partition => INT32
      error_code => INT16

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code

OffsetCommit Response (Version: 3) => throttle_time_ms [responses] 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition error_code 
      partition => INT32
      error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
error_code	Response error code

OffsetFetch API (Key: 9):

Requests:

OffsetFetch Request (Version: 0) => group_id [topics] 
  group_id => STRING
  topics => topic [partitions] 
    topic => STRING
    partitions => partition 
      partition => INT32

Field	Description
group_id	The unique group identifier
topics	Topics to fetch offsets.
topic	Name of topic
partitions	Partitions to fetch offsets.
partition	Topic partition id

OffsetFetch Request (Version: 1) => group_id [topics] 
  group_id => STRING
  topics => topic [partitions] 
    topic => STRING
    partitions => partition 
      partition => INT32

Field	Description
group_id	The unique group identifier
topics	Topics to fetch offsets.
topic	Name of topic
partitions	Partitions to fetch offsets.
partition	Topic partition id

OffsetFetch Request (Version: 2) => group_id [topics] 
  group_id => STRING
  topics => topic [partitions] 
    topic => STRING
    partitions => partition 
      partition => INT32

Field	Description
group_id	The unique group identifier
topics	Topics to fetch offsets. If the topic array is null fetch offsets for all topics.
topic	Name of topic
partitions	Partitions to fetch offsets.
partition	Topic partition id

OffsetFetch Request (Version: 3) => group_id [topics] 
  group_id => STRING
  topics => topic [partitions] 
    topic => STRING
    partitions => partition 
      partition => INT32

Field	Description
group_id	The unique group identifier
topics	Topics to fetch offsets. If the topic array is null fetch offsets for all topics.
topic	Name of topic
partitions	Partitions to fetch offsets.
partition	Topic partition id

Responses:

OffsetFetch Response (Version: 0) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition offset metadata error_code 
      partition => INT32
      offset => INT64
      metadata => NULLABLE_STRING
      error_code => INT16

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
offset	Last committed message offset.
metadata	Any associated metadata the client wants to keep.
error_code	Response error code

OffsetFetch Response (Version: 1) => [responses] 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition offset metadata error_code 
      partition => INT32
      offset => INT64
      metadata => NULLABLE_STRING
      error_code => INT16

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
offset	Last committed message offset.
metadata	Any associated metadata the client wants to keep.
error_code	Response error code

OffsetFetch Response (Version: 2) => [responses] error_code 
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition offset metadata error_code 
      partition => INT32
      offset => INT64
      metadata => NULLABLE_STRING
      error_code => INT16
  error_code => INT16

Field	Description
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
offset	Last committed message offset.
metadata	Any associated metadata the client wants to keep.
error_code	Response error code
error_code	Response error code

OffsetFetch Response (Version: 3) => throttle_time_ms [responses] error_code 
  throttle_time_ms => INT32
  responses => topic [partition_responses] 
    topic => STRING
    partition_responses => partition offset metadata error_code 
      partition => INT32
      offset => INT64
      metadata => NULLABLE_STRING
      error_code => INT16
  error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
responses	null
topic	Name of topic
partition_responses	null
partition	Topic partition id
offset	Last committed message offset.
metadata	Any associated metadata the client wants to keep.
error_code	Response error code
error_code	Response error code

FindCoordinator API (Key: 10):

Requests:

FindCoordinator Request (Version: 0) => group_id 
  group_id => STRING

Field	Description
group_id	The unique group identifier

FindCoordinator Request (Version: 1) => coordinator_key coordinator_type 
  coordinator_key => STRING
  coordinator_type => INT8

Field	Description
coordinator_key	Id to use for finding the coordinator (for groups, this is the groupId, for transactional producers, this is the transactional id)
coordinator_type	The type of coordinator to find (0 = group, 1 = transaction)

Responses:

FindCoordinator Response (Version: 0) => error_code coordinator 
  error_code => INT16
  coordinator => node_id host port 
    node_id => INT32
    host => STRING
    port => INT32

Field	Description
error_code	Response error code
coordinator	Host and port information for the coordinator for a consumer group.
node_id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.

FindCoordinator Response (Version: 1) => throttle_time_ms error_code error_message coordinator 
  throttle_time_ms => INT32
  error_code => INT16
  error_message => NULLABLE_STRING
  coordinator => node_id host port 
    node_id => INT32
    host => STRING
    port => INT32

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code
error_message	Response error message
coordinator	Host and port information for the coordinator
node_id	The broker id.
host	The hostname of the broker.
port	The port on which the broker accepts requests.

JoinGroup API (Key: 11):

Requests:

JoinGroup Request (Version: 0) => group_id session_timeout member_id protocol_type [group_protocols] 
  group_id => STRING
  session_timeout => INT32
  member_id => STRING
  protocol_type => STRING
  group_protocols => protocol_name protocol_metadata 
    protocol_name => STRING
    protocol_metadata => BYTES

Field	Description
group_id	The unique group identifier
session_timeout	The coordinator considers the consumer dead if it receives no heartbeat after this timeout in ms.
member_id	The member id assigned by the group coordinator or null if joining for the first time.
protocol_type	Unique name for class of protocols implemented by group
group_protocols	List of protocols that the member supports
protocol_name	null
protocol_metadata	null

JoinGroup Request (Version: 1) => group_id session_timeout rebalance_timeout member_id protocol_type [group_protocols] 
  group_id => STRING
  session_timeout => INT32
  rebalance_timeout => INT32
  member_id => STRING
  protocol_type => STRING
  group_protocols => protocol_name protocol_metadata 
    protocol_name => STRING
    protocol_metadata => BYTES

Field	Description
group_id	The unique group identifier
session_timeout	The coordinator considers the consumer dead if it receives no heartbeat after this timeout in ms.
rebalance_timeout	The maximum time that the coordinator will wait for each member to rejoin when rebalancing the group
member_id	The member id assigned by the group coordinator or null if joining for the first time.
protocol_type	Unique name for class of protocols implemented by group
group_protocols	List of protocols that the member supports
protocol_name	null
protocol_metadata	null

JoinGroup Request (Version: 2) => group_id session_timeout rebalance_timeout member_id protocol_type [group_protocols] 
  group_id => STRING
  session_timeout => INT32
  rebalance_timeout => INT32
  member_id => STRING
  protocol_type => STRING
  group_protocols => protocol_name protocol_metadata 
    protocol_name => STRING
    protocol_metadata => BYTES

Field	Description
group_id	The unique group identifier
session_timeout	The coordinator considers the consumer dead if it receives no heartbeat after this timeout in ms.
rebalance_timeout	The maximum time that the coordinator will wait for each member to rejoin when rebalancing the group
member_id	The member id assigned by the group coordinator or null if joining for the first time.
protocol_type	Unique name for class of protocols implemented by group
group_protocols	List of protocols that the member supports
protocol_name	null
protocol_metadata	null

Responses:

JoinGroup Response (Version: 0) => error_code generation_id group_protocol leader_id member_id [members] 
  error_code => INT16
  generation_id => INT32
  group_protocol => STRING
  leader_id => STRING
  member_id => STRING
  members => member_id member_metadata 
    member_id => STRING
    member_metadata => BYTES

Field	Description
error_code	Response error code
generation_id	The generation of the group.
group_protocol	The group protocol selected by the coordinator
leader_id	The leader of the group
member_id	The member id assigned by the group coordinator or null if joining for the first time.
members	null
member_id	The member id assigned by the group coordinator or null if joining for the first time.
member_metadata	null

JoinGroup Response (Version: 1) => error_code generation_id group_protocol leader_id member_id [members] 
  error_code => INT16
  generation_id => INT32
  group_protocol => STRING
  leader_id => STRING
  member_id => STRING
  members => member_id member_metadata 
    member_id => STRING
    member_metadata => BYTES

Field	Description
error_code	Response error code
generation_id	The generation of the group.
group_protocol	The group protocol selected by the coordinator
leader_id	The leader of the group
member_id	The member id assigned by the group coordinator or null if joining for the first time.
members	null
member_id	The member id assigned by the group coordinator or null if joining for the first time.
member_metadata	null

JoinGroup Response (Version: 2) => throttle_time_ms error_code generation_id group_protocol leader_id member_id [members] 
  throttle_time_ms => INT32
  error_code => INT16
  generation_id => INT32
  group_protocol => STRING
  leader_id => STRING
  member_id => STRING
  members => member_id member_metadata 
    member_id => STRING
    member_metadata => BYTES

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code
generation_id	The generation of the group.
group_protocol	The group protocol selected by the coordinator
leader_id	The leader of the group
member_id	The member id assigned by the group coordinator or null if joining for the first time.
members	null
member_id	The member id assigned by the group coordinator or null if joining for the first time.
member_metadata	null

Heartbeat API (Key: 12):

Requests:

Heartbeat Request (Version: 0) => group_id generation_id member_id 
  group_id => STRING
  generation_id => INT32
  member_id => STRING

Field	Description
group_id	The unique group identifier
generation_id	The generation of the group.
member_id	The member id assigned by the group coordinator or null if joining for the first time.

Heartbeat Request (Version: 1) => group_id generation_id member_id 
  group_id => STRING
  generation_id => INT32
  member_id => STRING

Field	Description
group_id	The unique group identifier
generation_id	The generation of the group.
member_id	The member id assigned by the group coordinator or null if joining for the first time.

Responses:

Heartbeat Response (Version: 0) => error_code 
  error_code => INT16

Field	Description
error_code	Response error code

Heartbeat Response (Version: 1) => throttle_time_ms error_code 
  throttle_time_ms => INT32
  error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code

LeaveGroup API (Key: 13):

Requests:

LeaveGroup Request (Version: 0) => group_id member_id 
  group_id => STRING
  member_id => STRING

Field	Description
group_id	The unique group identifier
member_id	The member id assigned by the group coordinator or null if joining for the first time.

LeaveGroup Request (Version: 1) => group_id member_id 
  group_id => STRING
  member_id => STRING

Field	Description
group_id	The unique group identifier
member_id	The member id assigned by the group coordinator or null if joining for the first time.

Responses:

LeaveGroup Response (Version: 0) => error_code 
  error_code => INT16

Field	Description
error_code	Response error code

LeaveGroup Response (Version: 1) => throttle_time_ms error_code 
  throttle_time_ms => INT32
  error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code

SyncGroup API (Key: 14):

Requests:

SyncGroup Request (Version: 0) => group_id generation_id member_id [group_assignment] 
  group_id => STRING
  generation_id => INT32
  member_id => STRING
  group_assignment => member_id member_assignment 
    member_id => STRING
    member_assignment => BYTES

Field	Description
group_id	The unique group identifier
generation_id	The generation of the group.
member_id	The member id assigned by the group coordinator or null if joining for the first time.
group_assignment	null
member_id	The member id assigned by the group coordinator or null if joining for the first time.
member_assignment	null

SyncGroup Request (Version: 1) => group_id generation_id member_id [group_assignment] 
  group_id => STRING
  generation_id => INT32
  member_id => STRING
  group_assignment => member_id member_assignment 
    member_id => STRING
    member_assignment => BYTES

Field	Description
group_id	The unique group identifier
generation_id	The generation of the group.
member_id	The member id assigned by the group coordinator or null if joining for the first time.
group_assignment	null
member_id	The member id assigned by the group coordinator or null if joining for the first time.
member_assignment	null

Responses:

SyncGroup Response (Version: 0) => error_code member_assignment 
  error_code => INT16
  member_assignment => BYTES

Field	Description
error_code	Response error code
member_assignment	null

SyncGroup Response (Version: 1) => throttle_time_ms error_code member_assignment 
  throttle_time_ms => INT32
  error_code => INT16
  member_assignment => BYTES

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code
member_assignment	null

DescribeGroups API (Key: 15):

Requests:

DescribeGroups Request (Version: 0) => [group_ids] 
  group_ids => STRING

Field	Description
group_ids	List of groupIds to request metadata for (an empty groupId array will return empty group metadata).

DescribeGroups Request (Version: 1) => [group_ids] 
  group_ids => STRING

Field	Description
group_ids	List of groupIds to request metadata for (an empty groupId array will return empty group metadata).

Responses:

DescribeGroups Response (Version: 0) => [groups] 
  groups => error_code group_id state protocol_type protocol [members] 
    error_code => INT16
    group_id => STRING
    state => STRING
    protocol_type => STRING
    protocol => STRING
    members => member_id client_id client_host member_metadata member_assignment 
      member_id => STRING
      client_id => STRING
      client_host => STRING
      member_metadata => BYTES
      member_assignment => BYTES

Field	Description
groups	null
error_code	Response error code
group_id	The unique group identifier
state	The current state of the group (one of: Dead, Stable, CompletingRebalance, PreparingRebalance, or empty if there is no active group)
protocol_type	The current group protocol type (will be empty if there is no active group)
protocol	The current group protocol (only provided if the group is Stable)
members	Current group members (only provided if the group is not Dead)
member_id	The member id assigned by the group coordinator or null if joining for the first time.
client_id	The client id used in the member's latest join group request
client_host	The client host used in the request session corresponding to the member's join group.
member_metadata	The metadata corresponding to the current group protocol in use (will only be present if the group is stable).
member_assignment	The current assignment provided by the group leader (will only be present if the group is stable).

DescribeGroups Response (Version: 1) => throttle_time_ms [groups] 
  throttle_time_ms => INT32
  groups => error_code group_id state protocol_type protocol [members] 
    error_code => INT16
    group_id => STRING
    state => STRING
    protocol_type => STRING
    protocol => STRING
    members => member_id client_id client_host member_metadata member_assignment 
      member_id => STRING
      client_id => STRING
      client_host => STRING
      member_metadata => BYTES
      member_assignment => BYTES

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
groups	null
error_code	Response error code
group_id	The unique group identifier
state	The current state of the group (one of: Dead, Stable, CompletingRebalance, PreparingRebalance, or empty if there is no active group)
protocol_type	The current group protocol type (will be empty if there is no active group)
protocol	The current group protocol (only provided if the group is Stable)
members	Current group members (only provided if the group is not Dead)
member_id	The member id assigned by the group coordinator or null if joining for the first time.
client_id	The client id used in the member's latest join group request
client_host	The client host used in the request session corresponding to the member's join group.
member_metadata	The metadata corresponding to the current group protocol in use (will only be present if the group is stable).
member_assignment	The current assignment provided by the group leader (will only be present if the group is stable).

ListGroups API (Key: 16):

Requests:

ListGroups Request (Version: 0) => 

Field	Description

ListGroups Request (Version: 1) => 

Field	Description

Responses:

ListGroups Response (Version: 0) => error_code [groups] 
  error_code => INT16
  groups => group_id protocol_type 
    group_id => STRING
    protocol_type => STRING

Field	Description
error_code	Response error code
groups	null
group_id	The unique group identifier
protocol_type	null

ListGroups Response (Version: 1) => throttle_time_ms error_code [groups] 
  throttle_time_ms => INT32
  error_code => INT16
  groups => group_id protocol_type 
    group_id => STRING
    protocol_type => STRING

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code
groups	null
group_id	The unique group identifier
protocol_type	null

SaslHandshake API (Key: 17):

Requests:

SaslHandshake Request (Version: 0) => mechanism 
  mechanism => STRING

Field	Description
mechanism	SASL Mechanism chosen by the client.

SaslHandshake Request (Version: 1) => mechanism 
  mechanism => STRING

Field	Description
mechanism	SASL Mechanism chosen by the client.

Responses:

SaslHandshake Response (Version: 0) => error_code [enabled_mechanisms] 
  error_code => INT16
  enabled_mechanisms => STRING

Field	Description
error_code	Response error code
enabled_mechanisms	Array of mechanisms enabled in the server.

SaslHandshake Response (Version: 1) => error_code [enabled_mechanisms] 
  error_code => INT16
  enabled_mechanisms => STRING

Field	Description
error_code	Response error code
enabled_mechanisms	Array of mechanisms enabled in the server.

ApiVersions API (Key: 18):

Requests:

ApiVersions Request (Version: 0) => 

Field	Description

ApiVersions Request (Version: 1) => 

Field	Description

Responses:

ApiVersions Response (Version: 0) => error_code [api_versions] 
  error_code => INT16
  api_versions => api_key min_version max_version 
    api_key => INT16
    min_version => INT16
    max_version => INT16

Field	Description
error_code	Response error code
api_versions	API versions supported by the broker.
api_key	API key.
min_version	Minimum supported version.
max_version	Maximum supported version.

ApiVersions Response (Version: 1) => error_code [api_versions] throttle_time_ms 
  error_code => INT16
  api_versions => api_key min_version max_version 
    api_key => INT16
    min_version => INT16
    max_version => INT16
  throttle_time_ms => INT32

Field	Description
error_code	Response error code
api_versions	API versions supported by the broker.
api_key	API key.
min_version	Minimum supported version.
max_version	Maximum supported version.
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

CreateTopics API (Key: 19):

Requests:

CreateTopics Request (Version: 0) => [create_topic_requests] timeout 
  create_topic_requests => topic num_partitions replication_factor [replica_assignment] [config_entries] 
    topic => STRING
    num_partitions => INT32
    replication_factor => INT16
    replica_assignment => partition [replicas] 
      partition => INT32
      replicas => INT32
    config_entries => config_name config_value 
      config_name => STRING
      config_value => NULLABLE_STRING
  timeout => INT32

Field	Description
create_topic_requests	An array of single topic creation requests. Can not have multiple entries for the same topic.
topic	Name of topic
num_partitions	Number of partitions to be created. -1 indicates unset.
replication_factor	Replication factor for the topic. -1 indicates unset.
replica_assignment	Replica assignment among kafka brokers for this topic partitions. If this is set num_partitions and replication_factor must be unset.
partition	Topic partition id
replicas	The set of all nodes that should host this partition. The first replica in the list is the preferred leader.
config_entries	Topic level configuration for topic to be set.
config_name	Configuration name
config_value	Configuration value
timeout	The time in ms to wait for a topic to be completely created on the controller node. Values <= 0 will trigger topic creation and return immediately

CreateTopics Request (Version: 1) => [create_topic_requests] timeout validate_only 
  create_topic_requests => topic num_partitions replication_factor [replica_assignment] [config_entries] 
    topic => STRING
    num_partitions => INT32
    replication_factor => INT16
    replica_assignment => partition [replicas] 
      partition => INT32
      replicas => INT32
    config_entries => config_name config_value 
      config_name => STRING
      config_value => NULLABLE_STRING
  timeout => INT32
  validate_only => BOOLEAN

Field	Description
create_topic_requests	An array of single topic creation requests. Can not have multiple entries for the same topic.
topic	Name of topic
num_partitions	Number of partitions to be created. -1 indicates unset.
replication_factor	Replication factor for the topic. -1 indicates unset.
replica_assignment	Replica assignment among kafka brokers for this topic partitions. If this is set num_partitions and replication_factor must be unset.
partition	Topic partition id
replicas	The set of all nodes that should host this partition. The first replica in the list is the preferred leader.
config_entries	Topic level configuration for topic to be set.
config_name	Configuration name
config_value	Configuration value
timeout	The time in ms to wait for a topic to be completely created on the controller node. Values <= 0 will trigger topic creation and return immediately
validate_only	If this is true, the request will be validated, but the topic won't be created.

CreateTopics Request (Version: 2) => [create_topic_requests] timeout validate_only 
  create_topic_requests => topic num_partitions replication_factor [replica_assignment] [config_entries] 
    topic => STRING
    num_partitions => INT32
    replication_factor => INT16
    replica_assignment => partition [replicas] 
      partition => INT32
      replicas => INT32
    config_entries => config_name config_value 
      config_name => STRING
      config_value => NULLABLE_STRING
  timeout => INT32
  validate_only => BOOLEAN

Field	Description
create_topic_requests	An array of single topic creation requests. Can not have multiple entries for the same topic.
topic	Name of topic
num_partitions	Number of partitions to be created. -1 indicates unset.
replication_factor	Replication factor for the topic. -1 indicates unset.
replica_assignment	Replica assignment among kafka brokers for this topic partitions. If this is set num_partitions and replication_factor must be unset.
partition	Topic partition id
replicas	The set of all nodes that should host this partition. The first replica in the list is the preferred leader.
config_entries	Topic level configuration for topic to be set.
config_name	Configuration name
config_value	Configuration value
timeout	The time in ms to wait for a topic to be completely created on the controller node. Values <= 0 will trigger topic creation and return immediately
validate_only	If this is true, the request will be validated, but the topic won't be created.

Responses:

CreateTopics Response (Version: 0) => [topic_errors] 
  topic_errors => topic error_code 
    topic => STRING
    error_code => INT16

Field	Description
topic_errors	An array of per topic error codes.
topic	Name of topic
error_code	Response error code

CreateTopics Response (Version: 1) => [topic_errors] 
  topic_errors => topic error_code error_message 
    topic => STRING
    error_code => INT16
    error_message => NULLABLE_STRING

Field	Description
topic_errors	An array of per topic errors.
topic	Name of topic
error_code	Response error code
error_message	Response error message

CreateTopics Response (Version: 2) => throttle_time_ms [topic_errors] 
  throttle_time_ms => INT32
  topic_errors => topic error_code error_message 
    topic => STRING
    error_code => INT16
    error_message => NULLABLE_STRING

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
topic_errors	An array of per topic errors.
topic	Name of topic
error_code	Response error code
error_message	Response error message

DeleteTopics API (Key: 20):

Requests:

DeleteTopics Request (Version: 0) => [topics] timeout 
  topics => STRING
  timeout => INT32

Field	Description
topics	An array of topics to be deleted.
timeout	The time in ms to wait for a topic to be completely deleted on the controller node. Values <= 0 will trigger topic deletion and return immediately

DeleteTopics Request (Version: 1) => [topics] timeout 
  topics => STRING
  timeout => INT32

Field	Description
topics	An array of topics to be deleted.
timeout	The time in ms to wait for a topic to be completely deleted on the controller node. Values <= 0 will trigger topic deletion and return immediately

Responses:

DeleteTopics Response (Version: 0) => [topic_error_codes] 
  topic_error_codes => topic error_code 
    topic => STRING
    error_code => INT16

Field	Description
topic_error_codes	An array of per topic error codes.
topic	Name of topic
error_code	Response error code

DeleteTopics Response (Version: 1) => throttle_time_ms [topic_error_codes] 
  throttle_time_ms => INT32
  topic_error_codes => topic error_code 
    topic => STRING
    error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
topic_error_codes	An array of per topic error codes.
topic	Name of topic
error_code	Response error code

DeleteRecords API (Key: 21):

Requests:

DeleteRecords Request (Version: 0) => [topics] timeout 
  topics => topic [partitions] 
    topic => STRING
    partitions => partition offset 
      partition => INT32
      offset => INT64
  timeout => INT32

Field	Description
topics	null
topic	Name of topic
partitions	null
partition	Topic partition id
offset	The offset before which the messages will be deleted. -1 means high-watermark for the partition.
timeout	The maximum time to await a response in ms.

Responses:

DeleteRecords Response (Version: 0) => throttle_time_ms [topics] 
  throttle_time_ms => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition low_watermark error_code 
      partition => INT32
      low_watermark => INT64
      error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
topics	null
topic	Name of topic
partitions	null
partition	Topic partition id
low_watermark	Smallest available offset of all live replicas
error_code	Response error code

InitProducerId API (Key: 22):

Requests:

InitProducerId Request (Version: 0) => transactional_id transaction_timeout_ms 
  transactional_id => NULLABLE_STRING
  transaction_timeout_ms => INT32

Field	Description
transactional_id	The transactional id or null if the producer is not transactional
transaction_timeout_ms	The time in ms to wait for before aborting idle transactions sent by this producer.

Responses:

InitProducerId Response (Version: 0) => throttle_time_ms error_code producer_id producer_epoch 
  throttle_time_ms => INT32
  error_code => INT16
  producer_id => INT64
  producer_epoch => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code
producer_id	Current producer id in use by the transactional id.
producer_epoch	Current epoch associated with the producer id.

OffsetForLeaderEpoch API (Key: 23):

Requests:

OffsetForLeaderEpoch Request (Version: 0) => [topics] 
  topics => topic [partitions] 
    topic => STRING
    partitions => partition leader_epoch 
      partition => INT32
      leader_epoch => INT32

Field	Description
topics	An array of topics to get epochs for
topic	Name of topic
partitions	null
partition	Topic partition id
leader_epoch	The epoch

Responses:

OffsetForLeaderEpoch Response (Version: 0) => [topics] 
  topics => topic [partitions] 
    topic => STRING
    partitions => error_code partition end_offset 
      error_code => INT16
      partition => INT32
      end_offset => INT64

Field	Description
topics	An array of topics for which we have leader offsets for some requested Partition Leader Epoch
topic	Name of topic
partitions	null
error_code	Response error code
partition	Topic partition id
end_offset	The end offset

AddPartitionsToTxn API (Key: 24):

Requests:

AddPartitionsToTxn Request (Version: 0) => transactional_id producer_id producer_epoch [topics] 
  transactional_id => STRING
  producer_id => INT64
  producer_epoch => INT16
  topics => topic [partitions] 
    topic => STRING
    partitions => INT32

Field	Description
transactional_id	The transactional id corresponding to the transaction.
producer_id	Current producer id in use by the transactional id.
producer_epoch	Current epoch associated with the producer id.
topics	The partitions to add to the transaction.
topic	Name of topic
partitions	null

Responses:

AddPartitionsToTxn Response (Version: 0) => throttle_time_ms [errors] 
  throttle_time_ms => INT32
  errors => topic [partition_errors] 
    topic => STRING
    partition_errors => partition error_code 
      partition => INT32
      error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
errors	null
topic	Name of topic
partition_errors	null
partition	Topic partition id
error_code	Response error code

AddOffsetsToTxn API (Key: 25):

Requests:

AddOffsetsToTxn Request (Version: 0) => transactional_id producer_id producer_epoch group_id 
  transactional_id => STRING
  producer_id => INT64
  producer_epoch => INT16
  group_id => STRING

Field	Description
transactional_id	The transactional id corresponding to the transaction.
producer_id	Current producer id in use by the transactional id.
producer_epoch	Current epoch associated with the producer id.
group_id	The unique group identifier

Responses:

AddOffsetsToTxn Response (Version: 0) => throttle_time_ms error_code 
  throttle_time_ms => INT32
  error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code

EndTxn API (Key: 26):

Requests:

EndTxn Request (Version: 0) => transactional_id producer_id producer_epoch transaction_result 
  transactional_id => STRING
  producer_id => INT64
  producer_epoch => INT16
  transaction_result => BOOLEAN

Field	Description
transactional_id	The transactional id corresponding to the transaction.
producer_id	Current producer id in use by the transactional id.
producer_epoch	Current epoch associated with the producer id.
transaction_result	The result of the transaction (0 = ABORT, 1 = COMMIT)

Responses:

EndTxn Response (Version: 0) => throttle_time_ms error_code 
  throttle_time_ms => INT32
  error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code

WriteTxnMarkers API (Key: 27):

Requests:

WriteTxnMarkers Request (Version: 0) => [transaction_markers] 
  transaction_markers => producer_id producer_epoch transaction_result [topics] coordinator_epoch 
    producer_id => INT64
    producer_epoch => INT16
    transaction_result => BOOLEAN
    topics => topic [partitions] 
      topic => STRING
      partitions => INT32
    coordinator_epoch => INT32

Field	Description
transaction_markers	The transaction markers to be written.
producer_id	Current producer id in use by the transactional id.
producer_epoch	Current epoch associated with the producer id.
transaction_result	The result of the transaction to write to the partitions (false = ABORT, true = COMMIT).
topics	The partitions to write markers for.
topic	Name of topic
partitions	null
coordinator_epoch	Epoch associated with the transaction state partition hosted by this transaction coordinator

Responses:

WriteTxnMarkers Response (Version: 0) => [transaction_markers] 
  transaction_markers => producer_id [topics] 
    producer_id => INT64
    topics => topic [partitions] 
      topic => STRING
      partitions => partition error_code 
        partition => INT32
        error_code => INT16

Field	Description
transaction_markers	Errors per partition from writing markers.
producer_id	Current producer id in use by the transactional id.
topics	Errors per partition from writing markers.
topic	Name of topic
partitions	null
partition	Topic partition id
error_code	Response error code

TxnOffsetCommit API (Key: 28):

Requests:

TxnOffsetCommit Request (Version: 0) => transactional_id group_id producer_id producer_epoch [topics] 
  transactional_id => STRING
  group_id => STRING
  producer_id => INT64
  producer_epoch => INT16
  topics => topic [partitions] 
    topic => STRING
    partitions => partition offset metadata 
      partition => INT32
      offset => INT64
      metadata => NULLABLE_STRING

Field	Description
transactional_id	The transactional id corresponding to the transaction.
group_id	The unique group identifier
producer_id	Current producer id in use by the transactional id.
producer_epoch	Current epoch associated with the producer id.
topics	The partitions to write markers for.
topic	Name of topic
partitions	null
partition	Topic partition id
offset	null
metadata	null

Responses:

TxnOffsetCommit Response (Version: 0) => throttle_time_ms [topics] 
  throttle_time_ms => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition error_code 
      partition => INT32
      error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
topics	Errors per partition from writing markers.
topic	Name of topic
partitions	null
partition	Topic partition id
error_code	Response error code

DescribeAcls API (Key: 29):

Requests:

DescribeAcls Request (Version: 0) => resource_type resource_name principal host operation permission_type 
  resource_type => INT8
  resource_name => NULLABLE_STRING
  principal => NULLABLE_STRING
  host => NULLABLE_STRING
  operation => INT8
  permission_type => INT8

Field	Description
resource_type	The resource type
resource_name	The resource name filter
principal	The ACL principal filter
host	The ACL host filter
operation	The ACL operation
permission_type	The ACL permission type

Responses:

DescribeAcls Response (Version: 0) => throttle_time_ms error_code error_message [resources] 
  throttle_time_ms => INT32
  error_code => INT16
  error_message => NULLABLE_STRING
  resources => resource_type resource_name [acls] 
    resource_type => INT8
    resource_name => STRING
    acls => principal host operation permission_type 
      principal => STRING
      host => STRING
      operation => INT8
      permission_type => INT8

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
error_code	Response error code
error_message	Response error message
resources	The resources and their associated ACLs.
resource_type	The resource type
resource_name	The resource name
acls	null
principal	The ACL principal
host	The ACL host
operation	The ACL operation
permission_type	The ACL permission type

CreateAcls API (Key: 30):

Requests:

CreateAcls Request (Version: 0) => [creations] 
  creations => resource_type resource_name principal host operation permission_type 
    resource_type => INT8
    resource_name => STRING
    principal => STRING
    host => STRING
    operation => INT8
    permission_type => INT8

Field	Description
creations	null
resource_type	The resource type
resource_name	The resource name
principal	The ACL principal
host	The ACL host
operation	The ACL operation
permission_type	The ACL permission type

Responses:

CreateAcls Response (Version: 0) => throttle_time_ms [creation_responses] 
  throttle_time_ms => INT32
  creation_responses => error_code error_message 
    error_code => INT16
    error_message => NULLABLE_STRING

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
creation_responses	null
error_code	Response error code
error_message	Response error message

DeleteAcls API (Key: 31):

Requests:

DeleteAcls Request (Version: 0) => [filters] 
  filters => resource_type resource_name principal host operation permission_type 
    resource_type => INT8
    resource_name => NULLABLE_STRING
    principal => NULLABLE_STRING
    host => NULLABLE_STRING
    operation => INT8
    permission_type => INT8

Field	Description
filters	null
resource_type	The resource type
resource_name	The resource name filter
principal	The ACL principal filter
host	The ACL host filter
operation	The ACL operation
permission_type	The ACL permission type

Responses:

DeleteAcls Response (Version: 0) => throttle_time_ms [filter_responses] 
  throttle_time_ms => INT32
  filter_responses => error_code error_message [matching_acls] 
    error_code => INT16
    error_message => NULLABLE_STRING
    matching_acls => error_code error_message resource_type resource_name principal host operation permission_type 
      error_code => INT16
      error_message => NULLABLE_STRING
      resource_type => INT8
      resource_name => STRING
      principal => STRING
      host => STRING
      operation => INT8
      permission_type => INT8

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
filter_responses	null
error_code	Response error code
error_message	Response error message
matching_acls	The matching ACLs
error_code	Response error code
error_message	Response error message
resource_type	The resource type
resource_name	The resource name
principal	The ACL principal
host	The ACL host
operation	The ACL operation
permission_type	The ACL permission type

DescribeConfigs API (Key: 32):

Requests:

DescribeConfigs Request (Version: 0) => [resources] 
  resources => resource_type resource_name [config_names] 
    resource_type => INT8
    resource_name => STRING
    config_names => STRING

Field	Description
resources	An array of config resources to be returned.
resource_type	null
resource_name	null
config_names	null

DescribeConfigs Request (Version: 1) => [resources] include_synonyms 
  resources => resource_type resource_name [config_names] 
    resource_type => INT8
    resource_name => STRING
    config_names => STRING
  include_synonyms => BOOLEAN

Field	Description
resources	An array of config resources to be returned.
resource_type	null
resource_name	null
config_names	null
include_synonyms	null

Responses:

DescribeConfigs Response (Version: 0) => throttle_time_ms [resources] 
  throttle_time_ms => INT32
  resources => error_code error_message resource_type resource_name [config_entries] 
    error_code => INT16
    error_message => NULLABLE_STRING
    resource_type => INT8
    resource_name => STRING
    config_entries => config_name config_value read_only is_default is_sensitive 
      config_name => STRING
      config_value => NULLABLE_STRING
      read_only => BOOLEAN
      is_default => BOOLEAN
      is_sensitive => BOOLEAN

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
resources	null
error_code	Response error code
error_message	Response error message
resource_type	null
resource_name	null
config_entries	null
config_name	null
config_value	null
read_only	null
is_default	null
is_sensitive	null

DescribeConfigs Response (Version: 1) => throttle_time_ms [resources] 
  throttle_time_ms => INT32
  resources => error_code error_message resource_type resource_name [config_entries] 
    error_code => INT16
    error_message => NULLABLE_STRING
    resource_type => INT8
    resource_name => STRING
    config_entries => config_name config_value read_only config_source is_sensitive [config_synonyms] 
      config_name => STRING
      config_value => NULLABLE_STRING
      read_only => BOOLEAN
      config_source => INT8
      is_sensitive => BOOLEAN
      config_synonyms => config_name config_value config_source 
        config_name => STRING
        config_value => NULLABLE_STRING
        config_source => INT8

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
resources	null
error_code	Response error code
error_message	Response error message
resource_type	null
resource_name	null
config_entries	null
config_name	null
config_value	null
read_only	null
config_source	null
is_sensitive	null
config_synonyms	null
config_name	null
config_value	null
config_source	null

AlterConfigs API (Key: 33):

Requests:

AlterConfigs Request (Version: 0) => [resources] validate_only 
  resources => resource_type resource_name [config_entries] 
    resource_type => INT8
    resource_name => STRING
    config_entries => config_name config_value 
      config_name => STRING
      config_value => NULLABLE_STRING
  validate_only => BOOLEAN

Field	Description
resources	An array of resources to update with the provided configs.
resource_type	null
resource_name	null
config_entries	null
config_name	Configuration name
config_value	Configuration value
validate_only	null

Responses:

AlterConfigs Response (Version: 0) => throttle_time_ms [resources] 
  throttle_time_ms => INT32
  resources => error_code error_message resource_type resource_name 
    error_code => INT16
    error_message => NULLABLE_STRING
    resource_type => INT8
    resource_name => STRING

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
resources	null
error_code	Response error code
error_message	Response error message
resource_type	null
resource_name	null

AlterReplicaLogDirs API (Key: 34):

Requests:

AlterReplicaLogDirs Request (Version: 0) => [log_dirs] 
  log_dirs => log_dir [topics] 
    log_dir => STRING
    topics => topic [partitions] 
      topic => STRING
      partitions => INT32

Field	Description
log_dirs	null
log_dir	The absolute log directory path.
topics	null
topic	Name of topic
partitions	List of partition ids of the topic.

Responses:

AlterReplicaLogDirs Response (Version: 0) => throttle_time_ms [topics] 
  throttle_time_ms => INT32
  topics => topic [partitions] 
    topic => STRING
    partitions => partition error_code 
      partition => INT32
      error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
topics	null
topic	Name of topic
partitions	null
partition	Topic partition id
error_code	Response error code

DescribeLogDirs API (Key: 35):

Requests:

DescribeLogDirs Request (Version: 0) => [topics] 
  topics => topic [partitions] 
    topic => STRING
    partitions => INT32

Field	Description
topics	null
topic	Name of topic
partitions	List of partition ids of the topic.

Responses:

DescribeLogDirs Response (Version: 0) => throttle_time_ms [log_dirs] 
  throttle_time_ms => INT32
  log_dirs => error_code log_dir [topics] 
    error_code => INT16
    log_dir => STRING
    topics => topic [partitions] 
      topic => STRING
      partitions => partition size offset_lag is_future 
        partition => INT32
        size => INT64
        offset_lag => INT64
        is_future => BOOLEAN

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
log_dirs	null
error_code	Response error code
log_dir	The absolute log directory path.
topics	null
topic	Name of topic
partitions	null
partition	Topic partition id
size	The size of the log segments of the partition in bytes.
offset_lag	The lag of the log's LEO w.r.t. partition's HW (if it is the current log for the partition) or current replica's LEO (if it is the future log for the partition)
is_future	True if this log is created by AlterReplicaLogDirsRequest and will replace the current log of the replica in the future.

SaslAuthenticate API (Key: 36):

Requests:

SaslAuthenticate Request (Version: 0) => sasl_auth_bytes 
  sasl_auth_bytes => BYTES

Field	Description
sasl_auth_bytes	SASL authentication bytes from client as defined by the SASL mechanism.

Responses:

SaslAuthenticate Response (Version: 0) => error_code error_message sasl_auth_bytes 
  error_code => INT16
  error_message => NULLABLE_STRING
  sasl_auth_bytes => BYTES

Field	Description
error_code	Response error code
error_message	Response error message
sasl_auth_bytes	SASL authentication bytes from server as defined by the SASL mechanism.

CreatePartitions API (Key: 37):

Requests:

CreatePartitions Request (Version: 0) => [topic_partitions] timeout validate_only 
  topic_partitions => topic new_partitions 
    topic => STRING
    new_partitions => count [assignment] 
      count => INT32
      assignment => ARRAY(INT32)
  timeout => INT32
  validate_only => BOOLEAN

Field	Description
topic_partitions	List of topic and the corresponding new partitions.
topic	Name of topic
new_partitions	null
count	The new partition count.
assignment	The assigned brokers.
timeout	The time in ms to wait for the partitions to be created.
validate_only	If true then validate the request, but don't actually increase the number of partitions.

Responses:

CreatePartitions Response (Version: 0) => throttle_time_ms [topic_errors] 
  throttle_time_ms => INT32
  topic_errors => topic error_code error_message 
    topic => STRING
    error_code => INT16
    error_message => NULLABLE_STRING

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
topic_errors	Per topic results for the create partitions request
topic	Name of topic
error_code	Response error code
error_message	Response error message

CreateDelegationToken API (Key: 38):

Requests:

CreateDelegationToken Request (Version: 0) => [renewers] max_life_time 
  renewers => principal_type name 
    principal_type => STRING
    name => STRING
  max_life_time => INT64

Field	Description
renewers	An array of token renewers. Renewer is an Kafka PrincipalType and name string, who is allowed to renew this token before the max lifetime expires.
principal_type	principalType of the Kafka principal
name	name of the Kafka principal
max_life_time	Max lifetime period for token in milli seconds. if value is -1, then max lifetime will default to a server side config value.

Responses:

CreateDelegationToken Response (Version: 0) => error_code owner issue_timestamp expiry_timestamp max_timestamp token_id hmac throttle_time_ms 
  error_code => INT16
  owner => principal_type name 
    principal_type => STRING
    name => STRING
  issue_timestamp => INT64
  expiry_timestamp => INT64
  max_timestamp => INT64
  token_id => STRING
  hmac => BYTES
  throttle_time_ms => INT32

Field	Description
error_code	Response error code
owner	token owner.
principal_type	principalType of the Kafka principal
name	name of the Kafka principal
issue_timestamp	timestamp (in msec) when this token was generated.
expiry_timestamp	timestamp (in msec) at which this token expires.
max_timestamp	max life time of this token.
token_id	UUID to ensure uniqueness.
hmac	HMAC of the delegation token.
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

RenewDelegationToken API (Key: 39):

Requests:

RenewDelegationToken Request (Version: 0) => hmac renew_time_period 
  hmac => BYTES
  renew_time_period => INT64

Field	Description
hmac	HMAC of the delegation token to be renewed.
renew_time_period	Renew time period in milli seconds.

Responses:

RenewDelegationToken Response (Version: 0) => error_code expiry_timestamp throttle_time_ms 
  error_code => INT16
  expiry_timestamp => INT64
  throttle_time_ms => INT32

Field	Description
error_code	Response error code
expiry_timestamp	timestamp (in msec) at which this token expires..
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

ExpireDelegationToken API (Key: 40):

Requests:

ExpireDelegationToken Request (Version: 0) => hmac expiry_time_period 
  hmac => BYTES
  expiry_time_period => INT64

Field	Description
hmac	HMAC of the delegation token to be expired.
expiry_time_period	expiry time period in milli seconds.

Responses:

ExpireDelegationToken Response (Version: 0) => error_code expiry_timestamp throttle_time_ms 
  error_code => INT16
  expiry_timestamp => INT64
  throttle_time_ms => INT32

Field	Description
error_code	Response error code
expiry_timestamp	timestamp (in msec) at which this token expires..
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

DescribeDelegationToken API (Key: 41):

Requests:

DescribeDelegationToken Request (Version: 0) => [owners] 
  owners => principal_type name 
    principal_type => STRING
    name => STRING

Field	Description
owners	An array of token owners.
principal_type	principalType of the Kafka principal
name	name of the Kafka principal

Responses:

DescribeDelegationToken Response (Version: 0) => error_code [token_details] throttle_time_ms 
  error_code => INT16
  token_details => owner issue_timestamp expiry_timestamp max_timestamp token_id hmac [renewers] 
    owner => principal_type name 
      principal_type => STRING
      name => STRING
    issue_timestamp => INT64
    expiry_timestamp => INT64
    max_timestamp => INT64
    token_id => STRING
    hmac => BYTES
    renewers => principal_type name 
      principal_type => STRING
      name => STRING
  throttle_time_ms => INT32

Field	Description
error_code	Response error code
token_details	null
owner	token owner.
principal_type	principalType of the Kafka principal
name	name of the Kafka principal
issue_timestamp	timestamp (in msec) when this token was generated.
expiry_timestamp	timestamp (in msec) at which this token expires.
max_timestamp	max life time of this token.
token_id	UUID to ensure uniqueness.
hmac	HMAC of the delegation token to be expired.
renewers	An array of token renewers. Renewer is an Kafka PrincipalType and name string, who is allowed to renew this token before the max lifetime expires.
principal_type	principalType of the Kafka principal
name	name of the Kafka principal
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)

DeleteGroups API (Key: 42):

Requests:

DeleteGroups Request (Version: 0) => [groups] 
  groups => STRING

Field	Description
groups	An array of groups to be deleted.

Responses:

DeleteGroups Response (Version: 0) => throttle_time_ms [group_error_codes] 
  throttle_time_ms => INT32
  group_error_codes => group_id error_code 
    group_id => STRING
    error_code => INT16

Field	Description
throttle_time_ms	Duration in milliseconds for which the request was throttled due to quota violation (Zero if the request did not violate any quota)
group_error_codes	An array of per group error codes.
group_id	The unique group identifier
error_code	Response error code

Some Common Philosophical Questions

Some people have asked why we don't use HTTP. There are a number of reasons, the best is that client implementors can make use of some of the more advanced TCP features--the ability to multiplex requests, the ability to simultaneously poll many connections, etc. We have also found HTTP libraries in many languages to be surprisingly shabby.

Others have asked if maybe we shouldn't support many different protocols. Prior experience with this was that it makes it very hard to add and test new features if they have to be ported across many protocol implementations. Our feeling is that most users don't really see multiple protocols as a feature, they just want a good reliable client in the language of their choice.

Another question is why we don't adopt XMPP, STOMP, AMQP or an existing protocol. The answer to this varies by protocol, but in general the problem is that the protocol does determine large parts of the implementation and we couldn't do what we are doing if we didn't have control over the protocol. Our belief is that it is possible to do better than existing messaging systems have in providing a truly distributed messaging system, and to do this we need to build something that works differently.

A final question is why we don't use a system like Protocol Buffers or Thrift to define our request messages. These packages excel at helping you to managing lots and lots of serialized messages. However we have only a few messages. Support across languages is somewhat spotty (depending on the package). Finally the mapping between binary log format and wire protocol is something we manage somewhat carefully and this would not be possible with these systems. Finally we prefer the style of versioning APIs explicitly and checking this to inferring new values as nulls as it allows more nuanced control of compatibility.