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Consumer identifier

· 2 min read
Piotr Gankiewicz
Piotr Gankiewicz
Iggy.rs founder

In the latest update, the Iggy server as well as the clients for all the available transport protocols have been extended with the support for consumer identifier. Whether you poll the messages, store the consumer offsets, or create consumer groups, you can use the well-established identifier type, instead of just u32, which is now a common standard for the resources' identification such as streams, topics, users and consumers.

Breaking changes​

The breaking changes have been introduced in Iggy server, starting from version 0.0.30 and Iggy SDK, starting from version 0.0.90. The final commit containing all the mentioned changes is #655f9b6.

Consumer identifier​

pub struct Consumer {
    pub kind: ConsumerKind,
    pub id: Identifier,
}

All the commands, such as PollMessages, StoreConsumerOffset and GetConsumerOffset which contain the consumer field, now require an update to the underlying serialization, as the id field is now an Identifier type, instead of u32. The serialization is the same, as when working with the stream, topic or user resources.

From now on, whenever working with the consumer or consumer group resource, you can use the numeric or text identifier.

Consumer groups​

pub struct CreateConsumerGroup {
    pub stream_id: Identifier,
    pub topic_id: Identifier,
    pub consumer_group_id: u32,
    pub name: String,
}

When creating the consumer group, the required name field has been added (must be unique per topic), and is serialized as usual, at the end of the payload, starting with the name length (4 bytes) and the name itself (N bytes).

pub struct DeleteConsumerGroup {
    pub stream_id: Identifier,
    pub topic_id: Identifier,
    pub consumer_group_id: Identifier,
}

pub struct GetConsumerGroup {
    pub stream_id: Identifier,
    pub topic_id: Identifier,
    pub consumer_group_id: Identifier,
}

pub struct JoinConsumerGroup {
    pub stream_id: Identifier,
    pub topic_id: Identifier,
    pub consumer_group_id: Identifier,
}

pub struct LeaveConsumerGroup {
    pub stream_id: Identifier,
    pub topic_id: Identifier,
    pub consumer_group_id: Identifier,
}

The DeleteConsumerGroup, GetConsumerGroup, JoinConsumerGroup and LeaveConsumerGroup commands have been extended with the consumer_group_id field, which is now an Identifier type, instead of u32.

pub struct ConsumerGroup {
    pub id: u32,
    pub name: String,
    pub partitions_count: u32,
    pub members_count: u32,
}

pub struct ConsumerGroupDetails {
    pub id: u32,
    pub name: String,
    pub partitions_count: u32,
    pub members_count: u32,
    pub members: Vec<ConsumerGroupMember>,
}

When fetching the consumer group(s), the ConsumerGroup and ConsumerGroupDetails structs have been extended with the name field, which serialized after members_count.