rpc Watch (stream WatchRequest) returns (stream WatchResponse) { }

message WatchRequest {
    oneof request_union {
        WatchCreateRequest create_request = 1;
        WatchCancelRequest cancel_request = 2;
        WatchProgressRequest progress_request = 3;
    }
}

message WatchCreateRequest {

    enum FilterType {
        NOPUT = 0;
        NODELETE = 1;
    }

    bytes key = 1;
    bytes range_end = 2;
    int64 start_revision = 3;

    // Request keepalive notifications
    bool progress_notify = 4;

    repeated FilterType filters = 5;

    bool prev_kv = 6;
    int64 watch_id = 7;
    bool fragment = 8;
}

message WatchResponse {
    ResponseHeader header = 1;
    int64 watch_id = 2;
    bool created = 3;
    bool canceled = 4;

    // Indicates attempt to watch already compacted revision
    int64 compact_revision = 5;

    string cancel_reason = 6;

    bool fragment = 7;

    repeated Event events = 11;
}

message Event {

    enum EventType {
        PUT = 0;
        DELETE = 1;
    }

    EventType type = 1;
    KeyValue kv = 2;
    KeyValue prev_kv = 3;
}