Metadata
This page encodes the smallest legal instance of the request and the response: numeric fields are zero, strings and byte arrays are empty, every array carries exactly one sample element, and any records field holds one empty 61-byte RecordBatch v2. Version 13 is a flexible version, so every struct is terminated by a uvarint tagged-field count and strings and arrays carry compact length-plus-one prefixes. Sizes below include the leading int32 size prefix.
- API key
- 3
- Encoded at
- v13
- Flexible versions
- 9+
- Headers
- req v2, resp v1
- Request versions
- 0-13
- Response versions
- 0-13
- Request size
- 37 bytes
- Response size
- 90 bytes
framerpc headerrequest bodyRecordBatchRecordresponse bodytagged_fields
Request
MetadataRequest v13, request header v2, 37 bytes on the wire
byte layout (37 bytes, 16 bytes per row)
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MetadataRequest message v13 [0x0000, 37B] +-- Frame [0x0000, 4B] length-delimited framing | +-- size int32 = 33 [0x0000, 4B] number of bytes that follow, patched after encoding +-- RequestHeader v2 [0x0004, 11B] common request header | +-- request_api_key int16 = 3 (Metadata) [0x0004, 2B] numeric id of the API being invoked | +-- request_api_version int16 = 13 [0x0006, 2B] version of the API being invoked | +-- correlation_id int32 = 0 [0x0008, 4B] echoed back by the broker in the response | +-- client_id nullable_string = "" (int16 len=0) [0x000c, 2B] always a non-flexible int16-prefixed string | +-- tagged_fields uvarint = 0 [0x000e, 1B] number of tagged fields in the header +-- MetadataRequest struct [0x000f, 22B] message body, version 13 +-- Topics []MetadataRequestTopic = 1 element [0x000f, 19B] The topics to fetch metadata for. | +-- length uvarint = 2 (compact, n+1) [0x000f, 1B] one sample element follows | +-- MetadataRequestTopic[0] MetadataRequestTopic = struct [0x0010, 18B] | +-- TopicId uuid = 00000000-0000-0000-0000-000000000000 [0x0010, 16B] The topic id. | +-- Name string = "" (compact, len+1=1) [0x0020, 1B] The topic name. | +-- tagged_fields uvarint = 0 [0x0021, 1B] number of tagged fields in this struct +-- AllowAutoTopicCreation bool = false [0x0022, 1B] If this is true, the broker may auto-create topics that we requested which ... +-- IncludeTopicAuthorizedOperations bool = false [0x0023, 1B] Whether to include topic authorized operations. +-- tagged_fields uvarint = 0 [0x0024, 1B] number of tagged fields in this struct
kafka message schema (.json)
{ "apiKey": 3, "type": "request", "listeners": ["broker"], "name": "MetadataRequest", "validVersions": "0-13", "flexibleVersions": "9+", "fields": [ // In version 0, an empty array indicates "request metadata for all topics." In version 1 and // higher, an empty array indicates "request metadata for no topics," and a null array is used to // indicate "request metadata for all topics." // // Version 2 and 3 are the same as version 1. // // Version 4 adds AllowAutoTopicCreation. // // Starting in version 8, authorized operations can be requested for cluster and topic resource. // // Version 9 is the first flexible version. // // Version 10 adds topicId and allows name field to be null. However, this functionality was not implemented on the server. // Versions 10 and 11 should not use the topicId field or set topic name to null. // // Version 11 deprecates IncludeClusterAuthorizedOperations field. This is now exposed // by the DescribeCluster API (KIP-700). // Version 12 supports topic Id. // Version 13 supports top-level error code in the response. { "name": "Topics", "type": "[]MetadataRequestTopic", "versions": "0+", "nullableVersions": "1+", "about": "The topics to fetch metadata for.", "fields": [ { "name": "TopicId", "type": "uuid", "versions": "10+", "ignorable": true, "about": "The topic id." }, { "name": "Name", "type": "string", "versions": "0+", "entityType": "topicName", "nullableVersions": "10+", "about": "The topic name." } ]}, { "name": "AllowAutoTopicCreation", "type": "bool", "versions": "4+", "default": "true", "ignorable": false, "about": "If this is true, the broker may auto-create topics that we requested which do not already exist, if it is configured to do so." }, { "name": "IncludeClusterAuthorizedOperations", "type": "bool", "versions": "8-10", "about": "Whether to include cluster authorized operations." }, { "name": "IncludeTopicAuthorizedOperations", "type": "bool", "versions": "8+", "about": "Whether to include topic authorized operations." } ] }
Response
MetadataResponse v13, response header v1, 90 bytes on the wire
byte layout (90 bytes, 16 bytes per row)
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MetadataResponse message v13 [0x0000, 90B] +-- Frame [0x0000, 4B] length-delimited framing | +-- size int32 = 86 [0x0000, 4B] number of bytes that follow, patched after encoding +-- ResponseHeader v1 [0x0004, 5B] common response header | +-- correlation_id int32 = 0 [0x0004, 4B] matches the correlation_id of the request | +-- tagged_fields uvarint = 0 [0x0008, 1B] number of tagged fields in the header +-- MetadataResponse struct [0x0009, 81B] message body, version 13 +-- ThrottleTimeMs int32 = 0 [0x0009, 4B] The duration in milliseconds for which the request was throttled due to a q... +-- Brokers []MetadataResponseBroker = 1 element [0x000d, 12B] A list of brokers present in the cluster. | +-- length uvarint = 2 (compact, n+1) [0x000d, 1B] one sample element follows | +-- MetadataResponseBroker[0] MetadataResponseBroker = struct [0x000e, 11B] | +-- NodeId int32 = 0 [0x000e, 4B] The broker ID. | +-- Host string = "" (compact, len+1=1) [0x0012, 1B] The broker hostname. | +-- Port int32 = 0 [0x0013, 4B] The broker port. | +-- Rack string = "" (compact, len+1=1) [0x0017, 1B] The rack of the broker, or null if it has not been assigned to a rack. | +-- tagged_fields uvarint = 0 [0x0018, 1B] number of tagged fields in this struct +-- ClusterId string = "" (compact, len+1=1) [0x0019, 1B] The cluster ID that responding broker belongs to. +-- ControllerId int32 = 0 [0x001a, 4B] The ID of the controller broker. +-- Topics []MetadataResponseTopic = 1 element [0x001e, 57B] Each topic in the response. | +-- length uvarint = 2 (compact, n+1) [0x001e, 1B] one sample element follows | +-- MetadataResponseTopic[0] MetadataResponseTopic = struct [0x001f, 56B] | +-- ErrorCode int16 = 0 [0x001f, 2B] The topic error, or 0 if there was no error. | +-- Name string = "" (compact, len+1=1) [0x0021, 1B] The topic name. Null for non-existing topics queried by ID. This is never n... | +-- TopicId uuid = 00000000-0000-0000-0000-000000000000 [0x0022, 16B] The topic id. Zero for non-existing topics queried by name. This is never z... | +-- IsInternal bool = false [0x0032, 1B] True if the topic is internal. | +-- Partitions []MetadataResponsePartition = 1 element [0x0033, 31B] Each partition in the topic. | | +-- length uvarint = 2 (compact, n+1) [0x0033, 1B] one sample element follows | | +-- MetadataResponsePartition[0] MetadataResponsePartition = struct [0x0034, 30B] | | +-- ErrorCode int16 = 0 [0x0034, 2B] The partition error, or 0 if there was no error. | | +-- PartitionIndex int32 = 0 [0x0036, 4B] The partition index. | | +-- LeaderId int32 = 0 [0x003a, 4B] The ID of the leader broker. | | +-- LeaderEpoch int32 = 0 [0x003e, 4B] The leader epoch of this partition. | | +-- ReplicaNodes []int32 = 1 element [0x0042, 5B] The set of all nodes that host this partition. | | | +-- length uvarint = 2 (compact, n+1) [0x0042, 1B] one sample element follows | | | +-- int32[0] int32 = 0 [0x0043, 4B] | | +-- IsrNodes []int32 = 1 element [0x0047, 5B] The set of nodes that are in sync with the leader for this partition. | | | +-- length uvarint = 2 (compact, n+1) [0x0047, 1B] one sample element follows | | | +-- int32[0] int32 = 0 [0x0048, 4B] | | +-- OfflineReplicas []int32 = 1 element [0x004c, 5B] The set of offline replicas of this partition. | | | +-- length uvarint = 2 (compact, n+1) [0x004c, 1B] one sample element follows | | | +-- int32[0] int32 = 0 [0x004d, 4B] | | +-- tagged_fields uvarint = 0 [0x0051, 1B] number of tagged fields in this struct | +-- TopicAuthorizedOperations int32 = 0 [0x0052, 4B] 32-bit bitfield to represent authorized operations for this topic. | +-- tagged_fields uvarint = 0 [0x0056, 1B] number of tagged fields in this struct +-- ErrorCode int16 = 0 [0x0057, 2B] The top-level error code, or 0 if there was no error. +-- tagged_fields uvarint = 0 [0x0059, 1B] number of tagged fields in this struct
kafka message schema (.json)
{ "apiKey": 3, "type": "response", "name": "MetadataResponse", // Version 1 adds fields for the rack of each broker, the controller id, and whether or not the topic is internal. // // Version 2 adds the cluster ID field. // // Version 3 adds the throttle time. // // Version 4 is the same as version 3. // // Version 5 adds a per-partition offline_replicas field. This field specifies // the list of replicas that are offline. // // Starting in version 6, on quota violation, brokers send out responses before throttling. // // Version 7 adds the leader epoch to the partition metadata. // // Starting in version 8, brokers can send authorized operations for topic and cluster. // // Version 9 is the first flexible version. // // Version 10 adds topicId. // // Version 11 deprecates ClusterAuthorizedOperations. This is now exposed // by the DescribeCluster API (KIP-700). // Version 12 supports topicId. // Version 13 supports top-level error code in the response. "validVersions": "0-13", "flexibleVersions": "9+", "fields": [ { "name": "ThrottleTimeMs", "type": "int32", "versions": "3+", "ignorable": true, "about": "The duration in milliseconds for which the request was throttled due to a quota violation, or zero if the request did not violate any quota." }, { "name": "Brokers", "type": "[]MetadataResponseBroker", "versions": "0+", "about": "A list of brokers present in the cluster.", "fields": [ { "name": "NodeId", "type": "int32", "versions": "0+", "mapKey": true, "entityType": "brokerId", "about": "The broker ID." }, { "name": "Host", "type": "string", "versions": "0+", "about": "The broker hostname." }, { "name": "Port", "type": "int32", "versions": "0+", "about": "The broker port." }, { "name": "Rack", "type": "string", "versions": "1+", "nullableVersions": "1+", "ignorable": true, "default": "null", "about": "The rack of the broker, or null if it has not been assigned to a rack." } ]}, { "name": "ClusterId", "type": "string", "nullableVersions": "2+", "versions": "2+", "ignorable": true, "default": "null", "about": "The cluster ID that responding broker belongs to." }, { "name": "ControllerId", "type": "int32", "versions": "1+", "default": "-1", "ignorable": true, "entityType": "brokerId", "about": "The ID of the controller broker." }, { "name": "Topics", "type": "[]MetadataResponseTopic", "versions": "0+", "about": "Each topic in the response.", "fields": [ { "name": "ErrorCode", "type": "int16", "versions": "0+", "about": "The topic error, or 0 if there was no error." }, { "name": "Name", "type": "string", "versions": "0+", "mapKey": true, "entityType": "topicName", "nullableVersions": "12+", "about": "The topic name. Null for non-existing topics queried by ID. This is never null when ErrorCode is zero. One of Name and TopicId is always populated." }, { "name": "TopicId", "type": "uuid", "versions": "10+", "ignorable": true, "about": "The topic id. Zero for non-existing topics queried by name. This is never zero when ErrorCode is zero. One of Name and TopicId is always populated." }, { "name": "IsInternal", "type": "bool", "versions": "1+", "default": "false", "ignorable": true, "about": "True if the topic is internal." }, { "name": "Partitions", "type": "[]MetadataResponsePartition", "versions": "0+", "about": "Each partition in the topic.", "fields": [ { "name": "ErrorCode", "type": "int16", "versions": "0+", "about": "The partition error, or 0 if there was no error." }, { "name": "PartitionIndex", "type": "int32", "versions": "0+", "about": "The partition index." }, { "name": "LeaderId", "type": "int32", "versions": "0+", "entityType": "brokerId", "about": "The ID of the leader broker." }, { "name": "LeaderEpoch", "type": "int32", "versions": "7+", "default": "-1", "ignorable": true, "about": "The leader epoch of this partition." }, { "name": "ReplicaNodes", "type": "[]int32", "versions": "0+", "entityType": "brokerId", "about": "The set of all nodes that host this partition." }, { "name": "IsrNodes", "type": "[]int32", "versions": "0+", "entityType": "brokerId", "about": "The set of nodes that are in sync with the leader for this partition." }, { "name": "OfflineReplicas", "type": "[]int32", "versions": "5+", "ignorable": true, "entityType": "brokerId", "about": "The set of offline replicas of this partition." } ]}, { "name": "TopicAuthorizedOperations", "type": "int32", "versions": "8+", "default": "-2147483648", "about": "32-bit bitfield to represent authorized operations for this topic." } ]}, { "name": "ClusterAuthorizedOperations", "type": "int32", "versions": "8-10", "default": "-2147483648", "about": "32-bit bitfield to represent authorized operations for this cluster." }, { "name": "ErrorCode", "type": "int16", "versions": "13+", "ignorable": true, "about": "The top-level error code, or 0 if there was no error." } ] }