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doc: add response header doc into api

release-3.0
Xiang Li 2016-04-14 18:54:54 -07:00
parent 74153ffa45
commit 3b72c3da53
1 changed files with 25 additions and 0 deletions
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Documentation/api_v3.md
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@ -2,6 +2,30 @@
TODO: finish API doc
## Response Header
All Responses from etcd API have a [response header][response_header] attached. The response header includes the metadata of the response.
```proto
message ResponseHeader {
uint64 cluster_id = 1;
uint64 member_id = 2;
int64 revision = 3;
uint64 raft_term = 4;
}
```
* Cluster_ID - the ID of the cluster that generates the response
* Member_ID - the ID of the member that generates the response
* Revision - the revision of the key-value store when the response is generated
* Raft_Term - the Raft term of the member when the response is generated
An application may read the Cluster_ID (Member_ID) field to ensure it is communicating with the intended cluster (member).
Applications can use the `Revision` to know the latest revision of the key-value store. This is especially useful when applications specify a historical revision to make time `travel query` and wishes to know the latest revision at the time of the request.
Applications can use `Raft_Term` to detect when the cluster completes a new leader election.
## Key-Value API
Key-Value API is used to manipulate key-value pairs stored inside etcd. The key-value API is defined as a [gRPC service][kv-service]. The Key-Value pair is defined as structured data in [protobuf format][kv-proto].
@ -119,3 +143,4 @@ etcd ensures linearizability for all other operations by default. Linearizabilit
[Linearizability]: #Linearizability
[kv-proto]: https://github.com/coreos/etcd/blob/master/storage/storagepb/kv.proto
[kv-service]: https://github.com/coreos/etcd/blob/master/etcdserver/etcdserverpb/rpc.proto
[response_header]: https://github.com/coreos/etcd/blob/master/etcdserver/etcdserverpb/rpc.proto