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All Kafka APIs

Envelope

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 0 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
58
Encoded at
v0
Flexible versions
0+
Headers
req v2, resp v1
Request versions
0
Response versions
0
Request size
19 bytes
Response size
13 bytes
framerpc headerrequest bodyRecordBatchRecordresponse bodytagged_fields

Request

EnvelopeRequest v0, request header v2, 19 bytes on the wire

byte layout (19 bytes, 16 bytes per row)

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object tree

EnvelopeRequest              message v0                                   [0x0000, 19B]
+-- Frame                                                                 [0x0000, 4B]   length-delimited framing
|   +-- size                 int32            = 15                        [0x0000, 4B]   number of bytes that follow, patched after encoding
+-- RequestHeader            v2                                           [0x0004, 11B]  common request header
|   +-- request_api_key      int16            = 58 (Envelope)             [0x0004, 2B]   numeric id of the API being invoked
|   +-- request_api_version  int16            = 0                         [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
+-- EnvelopeRequest          struct                                       [0x000f, 4B]   message body, version 0
    +-- RequestData          bytes            = empty (compact, len+1=1)  [0x000f, 1B]   The embedded request header and data.
    +-- RequestPrincipal     bytes            = empty (compact, len+1=1)  [0x0010, 1B]   Value of the initial client principal when the request is redirected by a b...
    +-- ClientHostAddress    bytes            = empty (compact, len+1=1)  [0x0011, 1B]   The original client's address in bytes.
    +-- tagged_fields        uvarint          = 0                         [0x0012, 1B]   number of tagged fields in this struct

kafka message schema (.json)

{
  "apiKey": 58,
  "type": "request",
  "listeners": ["controller"],
  "name": "EnvelopeRequest",
  // Request struct for forwarding.
  "validVersions": "0",
  "flexibleVersions": "0+",
  "fields": [
    { "name": "RequestData", "type": "bytes", "versions": "0+", "zeroCopy": true,
      "about": "The embedded request header and data."},
    { "name": "RequestPrincipal", "type": "bytes", "versions": "0+", "nullableVersions": "0+",
      "about": "Value of the initial client principal when the request is redirected by a broker." },
    { "name": "ClientHostAddress", "type": "bytes", "versions": "0+",
      "about": "The original client's address in bytes." }
  ]
}

Response

EnvelopeResponse v0, response header v1, 13 bytes on the wire

byte layout (13 bytes, 16 bytes per row)

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object tree

EnvelopeResponse        message v0                              [0x0000, 13B]
+-- Frame                                                       [0x0000, 4B]   length-delimited framing
|   +-- size            int32       = 9                         [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
+-- EnvelopeResponse    struct                                  [0x0009, 4B]   message body, version 0
    +-- ResponseData    bytes       = empty (compact, len+1=1)  [0x0009, 1B]   The embedded response header and data.
    +-- ErrorCode       int16       = 0                         [0x000a, 2B]   The error code, or 0 if there was no error.
    +-- tagged_fields   uvarint     = 0                         [0x000c, 1B]   number of tagged fields in this struct

kafka message schema (.json)

{
  "apiKey": 58,
  "type": "response",
  "name": "EnvelopeResponse",
  // Response struct for forwarding.
  "validVersions": "0",
  "flexibleVersions": "0+",
  "fields": [
    { "name": "ResponseData", "type": "bytes", "versions": "0+", "nullableVersions": "0+",
      "zeroCopy": true, "default": "null",
      "about": "The embedded response header and data."},
    { "name": "ErrorCode", "type": "int16", "versions": "0+",
      "about": "The error code, or 0 if there was no error." }
  ]
}