Protocol Compatibility Matrix

This document lists RobustMQ Kafka's compatibility per API: the supported version range, implementation status, and differences from native Kafka. It is the authoritative reference for deciding whether your client / tool can connect directly.

Status legend

Icon	Meaning
✅	Full: implemented per protocol semantics, ready to use
🟡	Partial: advertised and accepts requests, but semantics are trimmed (e.g. no-op, not enforced)
⚪	Intentionally unsupported: returns an explicit error instead of crashing; not offered by design
❌	Not implemented: not advertised in ApiVersions; clients using it fail fast

"Supported versions" is the range RobustMQ advertises in ApiVersions; where no version is noted, the API is handled at the version the client negotiates.

Data plane

Key	API	Versions	Status	Differences / Notes
0	Produce	v0–7	✅	Idempotent writes supported; transactional writes rejected; LogAppendTime not applied
1	Fetch	v4–13	✅	Consumer side always returns uncompressed records; no incremental fetch session; partition_leader_epoch=0; no read_committed
2	ListOffsets	v0–6	✅	earliest / latest / by timestamp
3	Metadata	v0–12	✅	Auto-creates topics by default (auto.create.topics.enable)

Consumer group (classic protocol)

Key	API	Versions	Status	Differences / Notes
8	OffsetCommit	—	✅	Commit consumed offsets
9	OffsetFetch	—	✅	v8 supports multi-group batch queries
10	FindCoordinator	v0–4	✅	Returns the coordinator for both group and transaction; transaction fails fast in later APIs
11	JoinGroup	v0–6	✅	Join a group, trigger rebalance
12	Heartbeat	—	✅	Maintain membership
13	LeaveGroup	—	✅	Voluntarily leave
14	SyncGroup	—	✅	Sync partition assignment
15	DescribeGroups	—	✅	Query group state
16	ListGroups	—	✅	List all groups
42	DeleteGroups	—	✅	Delete groups
47	OffsetDelete	—	✅	Delete committed offsets

Consumer group (KIP-848, next generation)

Key	API	Versions	Status	Differences / Notes
68	ConsumerGroupHeartbeat	v0–1	✅	Server-side assignment; no subscribed_topic_regex
69	ConsumerGroupDescribe	v0–1	✅	Query next-gen consumer groups

Idempotent Producer

Key	API	Versions	Status	Differences / Notes
22	InitProducerId	v0–3	✅	Idempotent only; with transactional_id returns TRANSACTIONAL_ID_AUTHORIZATION_FAILED

Authentication & handshake

Key	API	Versions	Status	Differences / Notes
17	SaslHandshake	v1	✅	Select SASL mechanism (SCRAM-SHA-256 / SCRAM-SHA-512)
18	ApiVersions	v0–4	✅	First request after connect, negotiates available APIs
36	SaslAuthenticate	—	✅	SASL token exchange

Topic / Partition management

Key	API	Versions	Status	Differences / Notes
19	CreateTopics	v0–7	✅	Rejects manual replica assignment (replicas managed by storage)
20	DeleteTopics	—	✅	Delete topics
21	DeleteRecords	—	✅	offset > HW returns OffsetOutOfRange
37	CreatePartitions	—	✅	Add partitions

Configuration management

Key	API	Versions	Status	Differences / Notes
32	DescribeConfigs	—	✅	Query configuration
33	AlterConfigs	—	✅	Modify configuration
44	IncrementalAlterConfigs	—	✅	Incrementally modify configuration
74	ListConfigResources	—	🟡	no-op: advertised but returns no resources

Most configs are storable but not enforced; see Compatibility & Limitations.

Cluster & operations

Key	API	Versions	Status	Differences / Notes
60	DescribeCluster	—	✅	Cluster info
75	DescribeTopicPartitions	v0	✅	Topic partition details
61	DescribeProducers	—	❌	Not advertised
34	AlterReplicaLogDirs	—	⚪	Intentionally unsupported (returns error, does not crash)
35	DescribeLogDirs	—	⚪	Intentionally unsupported
43	ElectLeaders	—	⚪	Intentionally unsupported (leaders managed by storage)
45	AlterPartitionReassignments	—	⚪	Intentionally unsupported (replicas auto-managed)
46	ListPartitionReassignments	—	⚪	Intentionally unsupported
57	UpdateFeatures	—	⚪	Intentionally unsupported

Security: ACL / quotas / SCRAM credentials

Key	API	Versions	Status	Differences / Notes
29	DescribeAcls	—	✅	Query ACLs (not enforced for authorization)
30	CreateAcls	—	✅	Create ACLs (not enforced)
31	DeleteAcls	—	✅	Delete ACLs (not enforced)
48	DescribeClientQuotas	—	✅	Query quotas (client-id only, not enforced for throttling)
49	AlterClientQuotas	—	✅	Modify quotas (not enforced)
50	DescribeUserScramCredentials	—	✅	Query SCRAM credentials
51	AlterUserScramCredentials	—	✅	Add/remove SCRAM credentials (SASL auth validates against these)

Delegation tokens

Key	API	Versions	Status	Differences / Notes
38	CreateDelegationToken	—	✅	Metadata management; tokens do not participate in auth
39	RenewDelegationToken	—	✅	Renew (metadata)
40	ExpireDelegationToken	—	✅	Expire (metadata)
41	DescribeDelegationToken	—	✅	Query (metadata)

Client telemetry (KIP-714)

Key	API	Versions	Status	Differences / Notes
71	GetTelemetrySubscriptions	—	🟡	no-op: accepted but no subscription pushed
72	PushTelemetry	—	🟡	no-op: accepted but metrics not processed

Transactions (unsupported)

The following APIs are not advertised in ApiVersions; clients enabling transactions fail fast.

Key	API	Status
24	AddPartitionsToTxn	❌
25	AddOffsetsToTxn	❌
26	EndTxn	❌
28	TxnOffsetCommit	❌
65	DescribeTransactions	❌
66	ListTransactions	❌

FindCoordinator returns a coordinator for transactions, but the subsequent transaction APIs fail immediately; InitProducerId supports idempotent mode only.

Share Group (KIP-932, unsupported)

All Share Group APIs are ❌ unsupported (ShareGroupHeartbeat / ShareGroupDescribe / ShareFetch / ShareAcknowledge / DescribeShareGroupOffsets / AlterShareGroupOffsets / DeleteShareGroupOffsets, etc.).

Further reading

• Core Concepts
• Compatibility & Limitations — root causes of the differences
• CLI Guide